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When will Lake Mead go dry?

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When will Lake Mead go dry?

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Abstract

A water budget analysis shows that under current conditions there is a 10% chance that live storage in Lakes Mead and Powell will be gone by about 2013 and a 50% chance that it will be gone by 2021 if no changes in water allocation from the Colorado River system are made. This startling result is driven by climate change associated with global warming, the effects of natural climate variability, and the current operating status of the reservoir system. Minimum power pool levels in both Lake Mead and Lake Powell will be reached under current conditions by 2017 with 50% probability. While these dates are subject to some uncertainty, they all point to a major and immediate water supply problem on the Colorado system. The solutions to this water shortage problem must be time-dependent to match the time-varying, human-induced decreases in future river flow.

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... Lake Mead-the largest reservoir in the CONUS by capacity-is critical to the regional socio-economic development (Christensen et al., 2004). Thus, the recent depletion of lake storage has raised great concern for the water managers in the Southwest (Barnett and Pierce, 2008). The average RELI value for Lake Mead from 1990 to 2014 is 65% (61%-67%). ...
... Because reservoirs accumulate all of the water from upstream, the changes of area/storage of downstream large reservoirs can be affected by climate change at a regional scale. For instance, the surface areas of the reservoirs in the southwestern region of the US have shown significant decreasing trends, which can be explained by the reduced precipitation during the last three decades (reported in Prein et al., 2016 andBarnett andPierce, 2008). This is particularly manifested in large reservoirs such as Lake Mead and Lake Powell. ...
... Because reservoirs accumulate all of the water from upstream, the changes of area/storage of downstream large reservoirs can be affected by climate change at a regional scale. For instance, the surface areas of the reservoirs in the southwestern region of the US have shown significant decreasing trends, which can be explained by the reduced precipitation during the last three decades (reported in Prein et al., 2016 andBarnett andPierce, 2008). This is particularly manifested in large reservoirs such as Lake Mead and Lake Powell. ...
Article
Evaporation from open surface water is a critical and continuous process in the water cycle. Globally, evaporation losses from reservoirs are estimated to be greater than the combined consumption from industrial and domestic water uses. However, this large volume of water loss is only coarsely considered in modern water resources management practices due to the complexities involved with quantifying these losses. By fusing remote sensing and modeling approaches, this study developed a novel method to accurately estimate the evaporation losses from 721 reservoirs in the contiguous United States (CONUS). Reservoir surface areas were extracted and enhanced from the Landsat based Global Surface Water Dataset (GSWD) from March 1984 to October 2015. The evaporation rate was modeled using the Penman Equation in which the lake heat storage term was considered. Validation results using in situ observations suggest that this approach can significantly improve the accuracy of the simulated monthly reservoir evaporation rate. The evaporation losses were subsequently estimated as the product of the surface area and evaporation rate. This paper presents a first of its kind, comprehensively validated, locally practical, and continentally consistent reservoir evaporation dataset. The results suggest that the long term averaged annual evaporation volume from these 721 reservoirs is 33.73 × 109 m3, which is equivalent to 93% of the annual public water supply of the United States (in 2010). An increasing trend of the evaporation rate (0.0076 mm/d/year) and a slightly decreasing trend of the total surface area (−0.011 × 109 m2/year) were both detected during the study period. As a result, the total evaporation shows an insignificant trend, yet with significant spatial heterogeneity. This new reservoir evaporation dataset can help facilitate more efficient water management practices.
... direct evaporation, withdrawals, reservoir outflow and groundwater percolation) (Duan and Bastiaanssen, 2013). A long-term imbalance can result in considerable reductions in water storage, as frequently observed around the globe in, for example, Lake Mead, Lake Powell, Lake Poopo and the Aral Sea (Barnett and Pierce, 2008;Micklin, 2016). Reduced water availability in the reservoirs may then result in reductions in hydropower energy production and/or irrigation water availability and lead to economic and societal damage. ...
... It is located approximately 50 km east of Las Vegas in the Black Canyon, Arizona-Nevada (Fig. 7). With a maximum depth of 158 m and a maximum capacity of 33-35 km 3 , Lake Mead is the largest reservoir in the US by capacity and the second largest (after Lake Powell) by water area (Barnett and Pierce, 2008;Holdren and Turner, 2010). The lake showed a considerable reduction in water storage between 1984 and 2015 (Fig. 6c). ...
... With an area of 653 km 2 , Lake Powell is the largest lake in the US by water surface area (Barnett and Pierce, 2008;Benenati et al., 2000). Its maximum capacity of 33.3 km 3 is slightly less than that of Lake Mead (Benenati et al., 2000;Holdren and Turner, 2010). ...
Article
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Lakes and reservoirs are crucial elements of the hydrological and biochemical cycle and are a valuable resource for hydropower, domestic and industrial water use, and irrigation. Although their monitoring is crucial in times of increased pressure on water resources by both climate change and human interventions, publically available datasets of lake and reservoir levels and volumes are scarce. Within this study, a time series of variation in lake and reservoir volume between 1984 and 2015 were analysed for 137 lakes over all continents by combining the JRC Global Surface Water (GSW) dataset and the satellite altimetry database DAHITI. The GSW dataset is a highly accurate surface water dataset at 30 m resolution compromising the whole L1T Landsat 5, 7 and 8 archive, which allowed for detailed lake area calculations globally over a very long time period using Google Earth Engine. Therefore, the estimates in water volume fluctuations using the GSW dataset are expected to improve compared to current techniques as they are not constrained by complex and computationally intensive classification procedures. Lake areas and water levels were combined in a regression to derive the hypsometry relationship (dh ∕ dA) for all lakes. Nearly all lakes showed a linear regression, and 42 % of the lakes showed a strong linear relationship with a R2 > 0.8, an average R2 of 0.91 and a standard deviation of 0.05. For these lakes and for lakes with a nearly constant lake area (coefficient of variation
... Furthermore, presently 15% of global freshwater is used for fossil fuel extraction, processing and power generation, while water requirements for renewable energy technologies, such as wind energy and solar photovoltaics (PV) are negligible (Irena, 2015). Water, energy and food security will be particularly vulnerable in the semi-arid Southwest of USA (Berardy andChester, 2017 andBarnett andPierce, 2008). Similarly, it will be shown that climate change and land use changes are already impacting average annual precipitation in the São Francisco basin which is critical for water, energy and food security in the Northeast (NE) region of Brazil. ...
... Furthermore, presently 15% of global freshwater is used for fossil fuel extraction, processing and power generation, while water requirements for renewable energy technologies, such as wind energy and solar photovoltaics (PV) are negligible (Irena, 2015). Water, energy and food security will be particularly vulnerable in the semi-arid Southwest of USA (Berardy andChester, 2017 andBarnett andPierce, 2008). Similarly, it will be shown that climate change and land use changes are already impacting average annual precipitation in the São Francisco basin which is critical for water, energy and food security in the Northeast (NE) region of Brazil. ...
... This has already happened to a number of other major rivers around the world, such as the Colorado River which runs dry well before reaching the sea (Howard, 2014 andBrown, 2006). Moreover, reservoir levels and hydroelectric generation along the Colorado River are also threatened by reduced runoff due to climate change and increasing human water consumption (Barnett and Pierce, 2008). The impact of droughts on the average monthly rainfall and streamflow in the São Francisco basin as well as hydroelectric availability and generation from 1996 to 2016 is shown in Fig. 12. ...
... Las Vegas relies heavily on Lake Mead for both public water supply and hydropower generation. With persistent drought conditions (16), water levels in Lake Mead have remained >70% below full pool (20), and Las Vegas recently completed the construction of a third intake extending deeper into the reservoir (21). Increases in water abstractions from increasing demands come at the expense of losses in hydroelectric generation at Hoover Dam (20). ...
... With persistent drought conditions (16), water levels in Lake Mead have remained >70% below full pool (20), and Las Vegas recently completed the construction of a third intake extending deeper into the reservoir (21). Increases in water abstractions from increasing demands come at the expense of losses in hydroelectric generation at Hoover Dam (20). Additionally, limited storage in Lake Mead reduces the flexibility to support environmental flows for protection of endangered species and preventing native species replacement by nonindigenous species (16). ...
... Additionally, limited storage in Lake Mead reduces the flexibility to support environmental flows for protection of endangered species and preventing native species replacement by nonindigenous species (16). Assuming no changes in water allocation strategies, Lake Mead has a 50% probability of losing all usable storage in the next 4 y, which would lead to complete collapse of the agricultural industry and public water supply for the entire region (20). ...
Article
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Cities are concentrations of sociopolitical power and prime architects of land transformation, while also serving as consumption hubs of "hard" water and energy infrastructures. These infrastructures extend well outside metropolitan boundaries and impact distal river ecosystems. We used a comprehensive model to quantify the roles of anthropogenic stressors on hydrologic alteration and biodiversity in US streams and isolate the impacts stemming from hard infrastructure developments in cities. Across the contiguous United States, cities' hard infrastructures have significantly altered at least 7% of streams, which influence habitats for over 60% of North America's fish, mussel, and crayfish species. Additionally, city infrastructures have contributed to local extinctions in 260 species and currently influence 970 indigenous species, 27% of which are in jeopardy. We find that ecosystem impacts do not scale with city size but are instead proportionate to infrastructure decisions. For example, Atlanta's impacts by hard infrastructures extend across four major river basins, 12,500 stream km, and contribute to 100 local extinctions of aquatic species. In contrast, Las Vegas, a similar size city, impacts <1,000 stream km, leading to only seven local extinctions. So, cities have local policy choices that can reduce future impacts to regional aquatic ecosystems as they grow. By coordinating policy and communication between hard infrastructure sectors, local city governments and utilities can directly improve environmental quality in a significant fraction of the nation's streams reaching far beyond their city boundaries.
... As recently reported by the Colorado River Research Group (2018) [1], water supply of the Colorado River (hereafter "WS") has decreased in recent decades, while the river basins are facing the biggest drought in recorded history. In terms of climatic conditions, the decrease in WS is largely attributed to increasing temperatures that led to less snow and more water being evaporated than normal (Barnett et al. 2008, McCabe et al. 2007, Udall et al. 2017) [2][3][4]. However, the long-term future of the WS made by climate model projections showed an upturn in the Colorado River WS into 2020 (BOR 2012) [5]; this is in contradiction to an observed decrease through 2018. ...
... As recently reported by the Colorado River Research Group (2018) [1], water supply of the Colorado River (hereafter "WS") has decreased in recent decades, while the river basins are facing the biggest drought in recorded history. In terms of climatic conditions, the decrease in WS is largely attributed to increasing temperatures that led to less snow and more water being evaporated than normal (Barnett et al. 2008, McCabe et al. 2007, Udall et al. 2017) [2][3][4]. However, the long-term future of the WS made by climate model projections showed an upturn in the Colorado River WS into 2020 (BOR 2012) [5]; this is in contradiction to an observed decrease through 2018. ...
... The concept is to examine multi-year predictability in water supply by conducting time series modeling that uses observational data of the GSL water level and the Colorado River WS. The work presented here does not analyze the mean-state hydroclimate changes toward the end of the century, which has already been done (Barnett et al. 2008) [2], nor does it apply climate indices to enhance seasonal prediction for the Colorado River WS. To this end, data and the time series modeling are introduced in Section 2. Results and validation of the two modeling approaches are presented in Sections 2.2 and 2.3, respectively. ...
Article
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The future of the Colorado River water supply (WS) affects millions of people and the U.S. economy. A recent study suggested a cross-basin correlation between the Colorado River and its neighboring Great Salt Lake (GSL). Following that study, the feasibility of using the previously developed multi-year prediction of the GSL water level to forecast the Colorado River WS was tested. Time-series models were developed to predict the changes in WS out to 10 years. Regressive methods and the GSL water level data were used for the depiction of decadal variability of the Colorado River WS. Various time-series models suggest a decline in the 10-year-averaged WS since 2013 before starting to increase around 2020. Comparison between this WS prediction and the WS projection published in a 2012 government report (derived from climate models) reveals a widened imbalance between supply and demand by 2020, a tendency that is confirmed by updated WS observation. Such information could aid in management decision making in the face of near-future water shortages.
... In recent decades, some of the water bodies around the world, such as Lake Eyre, Lake Mead, Lake Poopó, Dead Sea and Aral Sea have shrunk mainly due to drought and anthropogenic factors (Barnett and Pierce, 2008;Izdebski et al., 2016;Satgé et al., 2017;Farebrother et al., 2017). Dust storms and soil degradation as a result of drying up of these lakes have negative effects on human health and also on the environment. ...
... Dust storms and soil degradation as a result of drying up of these lakes have negative effects on human health and also on the environment. (Barnett and Pierce., 2008;Izdebski et al., 2016;Satgé et al., 2017;Farebrother et al., 2017). Urmia Lake, the largest inland lake in Iran has lost most of its water body in the last 2 decades mainly due to water mismanagement and drought in the catchment area (Hassanzadeh et al., 2012;Chaudhari et al., 2018;Alizade Govarchin Ghale et al., 2018;Khazaei et al., 2019;Alizade Govarchin Ghale et al., 2019). ...
Article
Urmia Lake, the largest inland lake in Iran has lost most of its water surface area in the last 2 decades. The desertification caused by the drying of this unique lake may lead to dust storms from the lakebed and affect the air quality of the region. In this study, MODIS derived Aerosol Optical Depth (AOD) data observed between 2000 and 2019, Ultra Violet Aerosol Index (UVAI) data from Ozone Monitoring Instrument (OMI), meteorological data from MERRA-2 and ground-level PM10 data measured in the northwestern Iran and eastern Turkey were used to investigate the effects of the drying of Urmia Lake on local and regional aerosol pollution. The results revealed significant increase in aerosol pollution over the last 10 years. An inverse relationship was observed between water level fluctuations of Urmia Lake and aerosol pollution in the northwestern Iran. In total, 177 days (27 days in the period of 2000–2009 and 150 days in the period of 2010–2019) with mean daily AOD values equal to or greater than 1 were observed over the box covering Urmia Lake Basin (ULB). During 2000–2009, when the mean AOD was 0.25, the mean water surface area of the lake was observed to be 4000 km2. When the lake dried up faster during 2010–2019 (the mean water surface area was observed 2100 km2), the mean AOD increased to 0.42. The eastern part of the lake was more polluted than western part due to the extent of salinization and desertification in this part and the prevailing wind direction from west to east. The results indicated similar trends with PM10 concentration in the northwestern Iran and eastern Turkey but the classification of PM10 values based on wind direction and wind speed rejected the influence of the lakebed on aerosol pollution in the eastern Turkey except in special meteorological conditions. These conditions occur when a low-pressure system over central Iraq and a high-pressure system located in a more northerly part of the region, mainly over the Caucasian, form a dust channel. In addition to dust storms from Iraq, Syria, Arabian Desert and local emission sources, the lakebed contributes as a new source of aerosol pollution mainly in the northwestern Iran and close regions.
... This consumptive use of water is highly regulated; in the downstream portion of the river, California, Arizona, and Nevada are allocated fixed volumes of water each year, each of which is used in its entirety (MacDonnell 2009). More water has been promised to users than flows down the Colorado River in an average year, and so the water storage of reservoirs on the river has decreased in most years of the 21st century (Barnett and Pierce 2008). This unsustainable situation is exacerbated by an ongoing, long-term decrease in annual flow volumes of the Colorado River, a phenomenon that may be caused by climate change (Webb et al. 2004;Barnett and Pierce 2008;USBR 2011a). ...
... More water has been promised to users than flows down the Colorado River in an average year, and so the water storage of reservoirs on the river has decreased in most years of the 21st century (Barnett and Pierce 2008). This unsustainable situation is exacerbated by an ongoing, long-term decrease in annual flow volumes of the Colorado River, a phenomenon that may be caused by climate change (Webb et al. 2004;Barnett and Pierce 2008;USBR 2011a). ...
Article
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A recent paper published time series of concentrations of chemicals in drinking water collected from the bottom of Lake Mead, a major American water supply reservoir. Data were compared to water level using only linear regression. This creates an opportunity for students to analyze these data further. This article presents a structured introduction to time series decomposition that compares long-term and seasonal components of a time series of a single chemical (meprobamate) with those of two supporting datasets (reservoir volume and specific conductance). For the chemical data, this must be preceded by estimation of missing datum points. Results show that linear regression analyses of time series data obscure meaningful detail and that specific conductance is the important predictor of seasonal chemical variations. To learn this, students must execute a linear regression, estimate missing data using local regression, decompose time series, and compare time series using cross-correlation. Complete R code for these exercises appears in the supplementary information. This article uses real data and requires that students make and justify key decisions about the analysis. It can be a guided or an individual project. It is scalable to instructor needs and student interests in ways that are identified clearly in this article.
... Worldwide, but especially in arid regions, the effects of climate change and rising temperatures threaten to reduce available surface water through enhanced evaporation, especially in surface storage reservoirs. Recently, reservoirs across the southwestern United States have been experiencing extremely low water levels, with water demands increasing and supplies decreasing (Figs. 1, 2;Fulp 2005; Barnett and Pierce 2008). The effective capacity of water stored by the mountain snowpack has been reduced by recent intense droughts, as well as from earlier snowmelt and runoff as a result of rising temperatures, rain-onsnow events, and enhanced dust on snow (Christensen et al. 2004;Seager et al. 2007; Barnett and Pierce 2008;Overpeck and Udall 2010;Rasmussen et al. 2014). ...
... Recently, reservoirs across the southwestern United States have been experiencing extremely low water levels, with water demands increasing and supplies decreasing (Figs. 1, 2;Fulp 2005; Barnett and Pierce 2008). The effective capacity of water stored by the mountain snowpack has been reduced by recent intense droughts, as well as from earlier snowmelt and runoff as a result of rising temperatures, rain-onsnow events, and enhanced dust on snow (Christensen et al. 2004;Seager et al. 2007; Barnett and Pierce 2008;Overpeck and Udall 2010;Rasmussen et al. 2014). ...
Article
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One way to adapt to and mitigate current and future water scarcity is to manage and store water more efficiently. Reservoirs act as critical buffers to ensure agricultural and municipal water deliveries, mitigate flooding, and generate hydroelectric power, yet they often lose significant amounts of water through evaporation, especially in arid and semiarid regions. Despite this fact, reservoir evaporation has been an inconsistently and inaccurately estimated component of the water cycle within the water resource infrastructure of the arid and semiarid western United States. This paper highlights the increasing importance and challenges of correctly estimating and forecasting reservoir evaporation in the current and future climate, as well as the need to bring new ideas and state-of-the-art practices for the estimation of reservoir evaporation into operational use for modern water resource managers. New ideas and practices include i) improving the estimation of reservoir evaporation using up-to-date knowledge, state-of-the-art instrumentation and numerical models, and innovative experimental designs to diagnose processes and accurately forecast evaporation; ii) improving our understanding of spatial and temporal variations in evaporative water loss from existing reservoirs and transferring this knowledge when expanding reservoirs or siting new ones; and iii) implementing an adaptive management plan that incorporates new knowledge, observations, and forecasts of reservoir evaporation to improve water resource management.
... If the drought continues, the lake level could drop below the municipal water intake pipe for Las Vegas in the next few years, and below the intake towers to run the electric turbines within the next ten years. 101 The increased heat and lower precipitation expected for the West will also lead to increased demand on the energy system for cooling, 102 and will double the incidences of wild fires. ...
... The Colorado River spans seven states in the western US and is a leading provider of 24 water for municipal use, agriculture, and power in the southwest. In the face of the warming 25 climate, numerous papers have warned about sizable water shortages of the Colorado River 26 [Barnett and Pierce, 2008;2009;Christensen et al., 2004;McCabe and Wolock, 2007;27 Rajagopalan et al., 2009]. In 2013, the Bureau of Reclamation (BOR) released a comprehensive 28 ...
Article
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The 2013 Bureau of Reclamation (BOR) Colorado River Basin Water Supply and Demand Study projected the water imbalance between future supply and demand to increase. The Colorado water supply (WS) exemplifies a pronounced quasi-decadal oscillation (QDO) of 10-20 years throughout its historical record, however this QDO feature is unaccounted for in the climate models used to project the future WS, a deficiency that is unlikely to be overcome soon. Adjacent to the Colorado River, the large watershed of Great Salt Lake (GSL) in Utah records the marked QDO in its water surface, leading previous studies to explore the cause of decadal fluctuations in the lake elevation and assess predictability. This study reports a remarkable coherence between the Colorado WS and the GSL elevation at the 10-20-year timescale. Analysis of precipitation and terrestrial water storage anomalies suggests a cross-basin connection in the climate and hydrometeorological variations of the Colorado WS and the GSL. The well-kept GSL elevation record makes it an effective indicator for the Colorado WS.
... Understanding the effects of EDCs in the major sub-basins in the LMNRA is a key to informing water-resource management, especially with regards to the continued reductions of Colorado River flow and lowering lake levels (Barnett and Pierce, 2008). Changes at the hormonal, cellular and molecular level precede changes at the organ and organismal level, which is why sperm biomarker assays were used here. ...
Article
Lake Mead National Recreational Area (LMNRA) serves as critical habitat for several federally listed species and supplies water for municipal, domestic, and agricultural use in the Southwestern U.S. Contaminant sources and concentrations vary among the sub-basins within LMNRA. To investigate whether exposure to environmental contaminants is associated with alterations in male common carp (Cyprinus carpio) gamete quality and endocrine- and reproductive parameters, data were collected among sub-basins over 7 years (1999-2006). Endpoints included sperm quality parameters of motility, viability, mitochondrial membrane potential, count, morphology, and DNA fragmentation; plasma components were vitellogenin (VTG), 17ß-estradiol, 11-keto-testosterone, triiodothyronine, and thyroxine. Fish condition factor, gonadosomatic index, and gonadal histology parameters were also measured. Diminished biomarker effects were noted in 2006, and sub-basin differences were indicated by the irregular occurrences of contaminants and by several associations between chemicals (e.g., polychlorinated biphenyls, hexachlorobenzene, galaxolide, and methyl triclosan) and biomarkers (e.g., plasma thyroxine, sperm motility and DNA fragmentation). By 2006, sex steroid hormone and VTG levels decreased with subsequent reduced endocrine disrupting effects. The sperm quality bioassays developed and applied with carp complemented endocrine and reproductive data, and can be adapted for use with other species.
... Furthermore, as shown in Figure 2, reservoir surface area dynamics can be evaluated. The example of Lake Mead (Figure 2a) shows continuous and unsustainable depletion of the reservoir storage, which is mainly caused by the changing climate and increasing consumptive water use (Barnett & Pierce, 2008). ...
Article
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The potential of using Landsat for assessing long-term water surface dynamics of individual reservoirs at a global scale has been significantly hindered by contaminations from clouds, cloud shadows, and terrain shadows. A novel algorithm was developed toward the automatic correction of these contaminated image classifications. By applying this algorithm to the data set by Pekel et al. (2016, https://doi.org/10.1038/nature20584), time series of area values for 6,817 global reservoirs (with an integrated capacity of 6,099 km³) were generated from 1984 to 2015. The number of effective images that can be used in each time series has been improved by 81% on average. The long-term average area for these global reservoirs was corrected from 1.73 × 10⁵ km² to 3.94 × 10⁵ km². The results were proven to be robust through validation using observations, synthetic data, and visual inspection. This continuous reservoir surface area data set can provide benefit to various applications (both at continental and local scales).
... Whilst this in part is caused by recent droughts, the long-term future of the reservoir, along with many others around the world, is under question. Barnett and Pierce (2008) examined a series of studies that found run-off into the Colorado River is expected to decrease by 10-30% over the next 30-50 years, due to changes in the catchment basin and potential decreases in future rainfall due to climate change. They predicted that based on projections of inflow then available, there was a 10% chance that Lake Mead would reach dead storage by 2013 and a 50% chance it would reach dead storage by 2021. ...
Thesis
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n general, a physical process is modelled in terms of how its state evolves over time. The main challenge of modelling is to describe this evolution without unnecessary computation or making unrealistic simplifying assumptions. Markov chains have found widespread applications in many fields of analytic study from engineering to biology to linguistics. One of their most notable applications in hydrological applications has been modelling the storage of reservoirs, as described in Moran's influential monograph (Moran, 1955). One of the fundamental properties of Markov chains is that the future evolution depends only on the present state, and not on any of the previous states. This property is simply stated as the “memory-less" property or the Markov property. In a Markov chain model the states representing the physical process are discrete, but time can be modelled as either discrete or continuous. In this thesis, time is modelled in discrete units because this is consistent with the well-established theory of Markov decision processes. The discrete states need not be a practical limitation because of continuous state variables, as in this case storage in a reservoir, can be discretised as a reasonable approximation. There have been many advances in Markov chain modelling techniques in other fields, most notably in telecommunications with the development of matrix analytic methods. Matrix analytic methods exploit the structure of certain types of Markov chains in order to more efficiently calculate properties of the models. This thesis examines how these methods can be applied to hydrological applications with the goal of providing a framework for which more precise modelling can be achieved without extending computational times. There are many unique challenges due to the seasonal nature of hydrology as well as the tendency for persistence of hydrological conditions. This thesis explores some of these problems in four papers. The first paper looks at the issues surrounding hydrological persistence and its incorporation into Markov decision processes using the Southern Oscillation Index as proxy. The second paper looks at modelling using matrix analytic methods of spate flows in the Cooper Creek, which is an ephemeral river located in the South Australia. The third paper looks at a way of modelling hydrological persistence with underlying hidden states in contrast to assumed dependence on the Southern Oscillation Index. The final paper looks at multi-objective optimisation using first-passage time distributions with an application to a two reservoir system in South East England. The Pareto front of Pareto optimal policies is shown.
... Warming temperatures have been documented for the Great Basin over the last century (Tang et al., 2014), with significant increases in annual minimum temperatures, leading to a decrease in the number of frost days. Climate models predict that the western United States will continue on a trend towards a warmer and dryer climate with temperature increases projected at 2 to 4 o C by 2050, with 11 of 12 global models predicting significant drying (Barnett & Pierce, 2008, McCabe & Wolock, 2007, Christensen et al., 2004. Groundwater diversion in these shrubland areas has been approved although still contested in court, allowing groundwater to potentially be pumped from east central Nevada basins to southern Nevada for municipal use to compensate for projected decreases in water supplies from the Colorado River and continued population growth (SNWA, 2012). ...
Article
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Shrubland species in the Great Basin (USA) depend on soil water recharged from precipitation and/or groundwater for survival and growth. Climate warming and possible basin water diversion could alter the amount and timing of water availability to these plants. The objective of this study was to quantify the extent to which each of four co-occurring shrub species, big sage [Artemisia tridentata], rabbitbrush [Ericameria nauseosus], greasewood [Sarcobatus vermiculatus] and shadscale [Atriplex confertifolia)) acquired water from different sources (precipitation, soil vadose zone and/or groundwater) during a growing season. Soil salinity increased linearly with depth over the upper 1.5 m of soil, with salinity ranging from 0.84 to 31.70 dSm-1 in saturation extracts (R2=0.78, p<0.001). Changes in soil water both with depth and time during the growing period indicated that all species accessed soil water from precipitation recharge. Evapotranspiration totals for the growing period exceeded total precipitation by 137 mm, indicating that plants also used water stored deeper within the vadose zone and/or from groundwater (particularly) by the phreatophyte greasewood. Delta18O in the soil solution declined linearly with depth over the upper 100 cm (R2=0.80, p<0.001). Delta18O values in greasewood corresponded closely to Delta18O values measured deeper in the vadose zone and groundwater. Output from a mixing model indicated a decrease in groundwater reliance for greasewood from 30% in July to 2% in September, with a major shift to deeper soil water in the vadose zone (180 cm depth) (38% in July to 97% in September). Our data suggested that the four shrub species at our site were able to coexist because of their different spatial, temporal, and physiological uses of available soil water, reflecting possible water resource partitioning based on differences in response to precipitation, ability to extract water at deeper depths and variable tolerance to elevated levels of soil salinity to access groundwater.
... Lentic ecosystems of the American Southwest, such as those in Utah, are susceptible to drought-driven lake elevation decline (Barnett & Pierce, 2008). Four of Utah's seven major droughts during the last century have occurred within the last 30 years, averaging 8.5 years in duration and causing lake elevation declines across multiple lakes in Utah (MacDonald, 2010;Utah Division of Water Resources, 2007). ...
Article
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• Multiyear drought is projected to increase in frequency and duration in arid and semiarid regions across the world, threatening native species and ecosystem function. The effects of multiyear drought are often exacerbated by human water use for consumption, energy production, and agriculture, which, in lentic ecosystems, manifest in reduced lake elevation and altered habitat for aquatic species. • Here, we demonstrate that decreasing lake levels, associated with drought and water management, reduce the availability of littoral cobble habitat to fishes by creating an elevation‐explicit littoral habitat map. We combined long‐term fish catch data and a lake elevation time series with our elevation‐explicit littoral habitat map to test whether fish species population demographics are related to drought‐driven changes in littoral habitat. • We surveyed the littoral zone of Bear Lake, Utah and Idaho, U.S.A., from full pool to a depth of >12 m, totalling 94.86 km² surveyed. As lake elevation decreased >6 m from full pool to the lowest historical elevation, the area of littoral cobble decreased by >97%. Bear Lake sculpin (Cottus extensus, Cottidae), a cold‐water fish species which relies on cobble for reproduction, catch per unit effort decreased by >75% with littoral cobble, and year class strength declined by as much as 86%, but varied across age. • We predicted the response of age‐0 to age‐4 sculpin under high and low cobble availability. Our simulations predict a 60%–85% decline in juvenile sculpin CPUE (age‐2 and younger) when cobble availability decreases from the 95th to 5th percentile. • Our study provided a unique opportunity to identify quantitative linkages between climate‐driven littoral habitat loss and an ecologically important profundal fish species, expanding our understanding of potential future pathways through which climate change may affect lentic ecosystems and fishes.
... In the case of United States, this population is projected to grow to 38 million by the 2030s (Day et al., 2016a). At present, Lake Mead be-hind the Hoover Dam is less than 50 percent capacity, and a recent study by scientists from Scripps Institution of Oceanography predicted that the lake had a 50 percent chance to drying up in two decades or less due to the combined eff ects of reduced river discharge and increasing rates of water evaporation and consumption (Barnett & Pierce, 2008). In fact, it is likely that Lake Mead will rarely, if ever, refi ll to capacity again. ...
Article
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The arid border region that encompasses the American Southwest and the Mexican northwest is an area where the nexus of water scarcity and climate change in the face of growing human demands for water, emerging energy scarcity, and economic change comes into sharp focus.
... At the average inflow and lake volume, the maximum length and width of Lake Mead are 180 km and 15 km, respectively; the length of the shoreline is 885 km; and the maximum depth and the mean depth are 158 m and 55.7 m, respectively (Holdren and Turner, 2010). Owing to climate change and current operation of reservoir system, Lake Mead's storage declined rapidly in recent years (Barnett and Pierce, 2008). From high-resolution satellite images from Google Earth, rock and bare land dominated the shoreline of Lake Mead. ...
... The dam storage capacities in central-western and southwestern United States are approximately four times higher than the dam mean annual runoff [35]. Created by the construction of the Hoover dam, Lake Mead is the largest reservoir in the US by water storage capacity and the second largest reservoir by surface water area, only surpassed by Lake Powell [36]. Lake Powell, formed by Glen Canyon dam, is the reservoir with the largest surface water area and sits further upstream on the Colorado river. ...
Article
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Globally, the number of dams increased dramatically during the 20th century. As a result, monitoring water levels and storage volume of dam-reservoirs has become essential in order to understand water resource availability amid changing climate and drought patterns. Recent advancements in remote sensing data show great potential for studies pertaining to long-term monitoring of reservoir water volume variations. In this study, we used freely available remote sensing products to assess volume variations for Lake Mead, Lake Powell and reservoirs in California between 1984 and 2015. Additionally, we provided insights on reservoir water volume fluctuations and hydrological drought patterns in the region. We based our volumetric estimations on the area-elevation hypsometry relationship, by combining water areas from the Global Surface Water (GSW) monthly water history (MWH) product with corresponding water surface median elevation values from three different digital elevation models (DEM) into a regression analysis. Using Lake Mead and Lake Powell as our validation reservoirs, we calculated a volumetric time series for the GSW MWH-DEM median elevation combinations that showed a strong linear 'area (W A)-elevation (W H)' (R 2 > 0.75) hypsometry. Based on 'W A-W H ' linearity and correlation analysis between the estimated and in situ volumetric time series, the methodology was expanded to reservoirs in California. Our volumetric results detected four distinct periods of water volume declines: for Lake Mead, Lake Powell and in 40 reservoirs in California. We also used multiscalar Standardized Precipitation Evapotranspiration Index (SPEI) for San Joaquin drainage in California to assess regional links between the drought indicators and reservoir volume fluctuations. We found highest correlations between reservoir volume variations and the SPEI at medium time scales (12-18-24-36 months). Our work demonstrates the potential of processed, open source remote sensing products for reservoir water volume variations and provides insights on usability of these variations in hydrological drought monitoring. Furthermore, the spatial coverage and long-term temporal availability of our data presents an opportunity to transfer these methods for volumetric analyses on a global scale.
... It does, however, offer a physically based explanation for the observed century-long decline in Colorado River streamflow within a new framework of the river's sensitivity to meteorological change. We recognize that explaining this decline is urgent because Lakes Mead and Powell are now approaching levels (Barnett and Pierce 2008) that may imminently require delivery curtailments, as per the 2007 Interim Guideline Agreement for handling water shortages on the river (https://www.usbr.gov/lc/ region/programs/strategies.html). ...
Article
Upper Colorado River basin streamflow has declined by roughly 20% over the last century of the instrumental period, based on estimates of naturalized flow above Lees Ferry. Here we assess factors causing the decline and evaluate the premise that rising surface temperatures have been mostly responsible. We use an event attribution framework involving parallel sets of global model experiments with and without climate change drivers. We demonstrate that climate change forcing has acted to reduce Upper Colorado River basin streamflow during this period by about 10% (with uncertainty range of 6%–14% reductions). The magnitude of the observed flow decline is found to be inconsistent with natural variability alone, and approximately one-half of the observed flow decline is judged to have resulted from long-term climate change. Each of three different global models used herein indicates that climate change forcing during the last century has acted to increase surface temperature (~+1.2°C) and decrease precipitation (~−3%). Using large ensemble methods, we diagnose the separate effects of temperature and precipitation changes on Upper Colorado River streamflow. Precipitation change is found to be the most consequential factor owing to its amplified impact on flow resulting from precipitation elasticity (percent change in streamflow per percent change in precipitation) of ~2. We confirm that warming has also driven streamflow declines, as inferred from empirical studies, although operating as a secondary factor. Our finding of a modest −2.5% °C ⁻¹ temperature sensitivity, on the basis of our best model-derived estimate, indicates that only about one-third of the attributable climate change signal in Colorado River decline resulted from warming, whereas about two-thirds resulted from precipitation decline.
... For example, Woodhouse et al. (2016) indicated that droughts over the basin have been amplified by warmer temperature relative to precipitation deficits. Under the current warming conditions, Barnett and Pierce (2008) showed that there is a 50% chance that storage in Lake Powell will be depleted by 2021. This projection is consistent with studies listed above that examined the impact of climate change on the basin. ...
Article
This study analyzes spatial and temporal characteristics of multiyear droughts and pluvials over the southwestern United States with a focus on the upper Colorado River basin. The study uses two multiscalar moisture indices: standardized precipitation evapotranspiration index (SPEI) and standardized precipitation index (SPI) on a 36-month scale (SPEI36 and SPI36, respectively). The indices are calculated from monthly average precipitation and maximum and minimum temperatures from the Parameter-Elevation Regressions on Independent Slopes Model dataset for the period 1950-2012. The study examines the relationship between individual climate variables as well as large-scale atmospheric circulation features found in reanalysis output during drought and pluvial periods. The results indicate that SPEI36 and SPI36 show similar temporal and spatial patterns, but that the inclusion of temperatures in SPEI36 leads to more extreme magnitudes in SPEI36 than in SPI36. Analysis of large-scale atmospheric fields indicates an interplay between different fields that yields extremes over the study region. Widespread drought (pluvial) events are associated with enhanced positive (negative) 500-hPa geopotential height anomaly linked to subsidence (ascent) and negative (positive) moisture convergence and precipitable water anomalies. Considering the broader context of the conditions responsible for the occurrence of prolonged hydrologic anomalies provides water resource managers and other decision-makers with valuable understanding of these events. This perspective also offers evaluation opportunities for climate models.
... As recently reported by the Colorado River Research Group [2018], water supply of the Colorado River (hereafter "WS") has decreased in recent decades while the river basins are facing the biggest drought in history (https://www.coloradoriverresearchgroup.org/). These changes have largely been attributed to increasing temperatures that led to less snow and more water being evaporated than normal [Barnett and Pierce, 2008;McCabe and Wolock, 2007;Udall and Overpeck, 2017]. However, the long-term future of the WS made by climate model projections showed an upturn in the Colorado River WS into 2020 [BOR, 2012]; this is in contradiction to an observed decrease through 2018. ...
Preprint
The future of the Colorado River water supply (WS) affects millions of people and the U.S. economy. A recent study suggested a cross-basin correlation between the Colorado River and its neighboring Great Salt Lake (GSL). Following that study, the feasibility of using the previously developed multi-year prediction of the GSL water level to forecast the Colorado River WS was tested. Time-series models were developed to predict the changes in WS out to 10 years. Regressive methods and the GSL water level data were used for the depiction of decadal variability of the Colorado River WS. Various time-series models suggest a decline in the 10-year-averaged WS since 2013 before starting to increase around 2020. Comparison between this WS prediction and the WS projection published in a 2012 government report (derived from climate models) reveals a widened imbalance between supply and demand by 2020, a tendency that is confirmed by updated WS observation. Such information could aid in management decision making in the face of near-future water shortages.
... According to an analysis performed by Barsugli et al., Lake Mead has a 50% percent chance of going dry between 2035 and 2047 if nothing is done to stop the current draw down and evaporation rate of the lake [100]. Other studies on the management of the lake have resulted in the same conclusion [101,102]. These studies have shown the need for new ways to mitigate lake evaporation not only on Lake Mead, but on other lakes in the world, especially those located in arid environments. ...
Article
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A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per unit power. Therefore, foam-based FPV provides a potentially profitable means of reducing water evaporation in the world’s at-risk bodies of fresh water. The case study of Lake Mead found that if 10% of the lake was covered with foam-backed FPV, there would be enough water conserved and electricity generated to service Las Vegas and Reno combined. At 50% coverage, the foam-backed FPV would provide over 127 TWh of clean solar electricity and 633.22 million m3 of water savings, which would provide enough electricity to retire 11% of the polluting coal-fired plants in the U.S. and provide water for over five million Americans, annually.
... UHI is a particularly important issue for the desert cities of southwestern United States, as climate change is bringing even hotter and drier conditions to the region, which is experiencing substantial population growth (Christensen and Lettenmaier, 2007;Seager et al., 2007;Barnett and Pierce, 2008). For example, Phoenix, Arizona's mean daily temperature has increased by 3.1°C during the last 50 years due to climate change and rapid urbanization, while summer nighttime temperatures have increased by as much as 6°C (Brazel et al., 2000). ...
Article
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Human-induced climate change is bringing warmer conditions to the Southwestern United States. More extreme urban heat island (UHI) effects are not distributed equally, and often impact socioeconomically vulnerable populations the most. This study aims to quantify how land surface temperature (LST) changes with increasing green vegetation landscapes, identify disparities in urban warming exposure, and provide a method for developing evidence-based mitigation options. ECOSTRESS LST products, detailed land use and land cover (LULC) classes, and socioeconomic variables were used to facilitate the analysis. We examined the relationship between LST and the fractions of LULC and socioeconomic factors in the city of Phoenix, Arizona. A machine learning approach (Random Forest) was used to model LST changes by taking the LULC fractions (scenario-based approaches) as the explanatory variables. We found that vegetation features-trees, grass, and shrubs-were the most important factors mitigating UHI effects during the summer daytime. Trees tended to lower surface temperature more effectively, whereas we observed elevated daytime LST most often near roads. Meanwhile, higher summer daytime temperatures were observed on land with unmanaged soil compared to the built environment. We found that affluent neighborhoods experienced lower temperatures, while low-income communities experienced higher temperatures. Scenario analyses suggest that replacing 50% of unmanaged soil with trees could reduce average summer daytime temperatures by 1.97°C if the intervention was implemented across all of Phoenix and by 1.43°C if implemented within the urban core only. We suggest that native trees requiring little to no additional water other than rainfall should be considered. We quantify mitigation options for urban warming effect under vegetation management interventions, and our results provide some vital insight into existing disparities in UHI impacts. Future UHI mitigation strategies seriously need to consider low-income communities to improve environmental justice. These can be used to guide the development of sustainable and equitable policies for vegetation management to mitigate heat exposure impacts on communities.
... Environmental flows are defined as the quantity, timing, duration, frequency, and quality of water flows required for the sustainability of fresh water, estuarine, and costal ecosystems and the human livelihoods and well-being that depend on them, which play a critical role in ecosystem restoration and water resource management (Pang et al., 2018;Arthington et al., 2006;Sun et al., 2007;McCartney et al., 2009;Gerten et al., 2013;Acreman & Ferguson, 2010;Jain, 2012). However, environmental flows are subject to stress from climate change and human activities, resulting in overexploitation of water resources, dryingup of rivers, serious river pollution, and degradation of ecosystems (Barnett & Pierce, 2008;Qureshi et al., 2011;Sims & Colloff, 2012). River ecosystems Abstract Monitoring environmental flows is crucial to maintaining the function and stability of river and lake ecosystems. ...
Article
Full-text available
Monitoring environmental flows is crucial to maintaining the function and stability of river and lake ecosystems. However, current methods for monitoring environmental flows are expensive and ground based, and the accuracy of the results needs to be verified to evaluate the environmental flows. This evaluation is hampered by the problem of data shortages, such as hydrological and ecological data. In this study, a method for monitoring environmental flows is proposed using multisource high spatial and temporal resolution satellite data. A case study in the Yongding River Basin demonstrates that the method is feasible for monitoring the environmental flows of rivers in semiarid and arid areas. The results show that the environmental flows and months with large water discharges and shortages in the three control sections of the Yongding River Basin were different. Moreover, the downstream river width rarely met the environmental water demand, achieving this only for one period from 2017 to 2019 according to the three typical types of years (an average water year, a dry year, and an extremely dry year). This method and the results have applications in planning environmental flows and could improve the comprehensive management of the ecological environment in river basins.
... As global climate change and the effects of human activities intensify, effective management of environmental flows as the basin scale seems to be a common problem. There are few natural basins, and the physical process and mechanisms by which the water cycle is transformed have also undergone tremendous changes [9,10]. The Beijing-Tianjin-Hebei region is a crucial economic zone in China, and the Yongding (YD) River Basin is an important water conservation area and ecological barrier in this region. ...
Article
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Environmental flows play a vital role in ecosystem and water resource management. The regulation and management of environmental flows can improve the function and stability of river and lake ecosystems. However, current methods for assessing environmental flows mainly emphasize water management, and there is no complete set of regulations or early warning systems, especially in arid and semiarid basins. In this study, we proposed a method for environmental flows regulation and early warning with remote sensing and land cover data and carried out a case study in the Yongding River Basin, which is a basin typical of arid and semiarid areas. The results show that from 2001 to 2014 the mean precipitation was 17.90 × 109 m3, and the mean water consumption was 19.42 × 109 m3, indicating that the basin water budget was clearly unbalanced and that there was an overall deficiency. Notably, from 2005 to 2014 and in 2014, the available consumable water was less than the water consumption required for human activities, which both showed a trend of further reduction; therefore, long-term and annual early warnings should have been issued. The methods applied in this study and the study outcomes could help in the development of comprehensive management and ecological restoration plans, further improving the ecological environments of river basins.
... Furthermore, calculations indicate that 10 %-15 % of the Colorado River flow at Lees Ferry, Arizona, is comprised of water from northeastern Utah (Tingstad, 2010). Flow of the Colorado River is expected to decline 10 %-30 % from 2008 levels in the next 18 to 38 years based on streamflow modeling work, implying intense water deficits in the Colorado River system over the next century (Barnett and Pierce, 2008). ...
Article
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Rock glaciers are a prominent component of many alpine landscapes and constitute a significant water resource in some arid mountain environments. Here, we employ satellite-based interferometric synthetic aperture radar (InSAR) between 2016 and 2019 to identify and monitor active and transitional rock glaciers in the Uinta Mountains (Utah, USA), an area of ∼3000 km2. We used mean velocity maps to generate an inventory for the Uinta Mountains containing 205 active and transitional rock glaciers. These rock glaciers are 11.9 ha in area on average and located at a mean elevation of 3308 m, where mean annual air temperature is −0.25 ∘C. The mean downslope velocity for the inventory is 1.94 cm yr−1, but individual rock glaciers have velocities ranging from 0.35 to 6.04 cm yr−1. To search for relationships with climatic drivers, we investigated the time-dependent motion of three rock glaciers. We found that rock glacier motion has a significant seasonal component, with rates that are more than 5 times faster during the late summer compared to the rest of the year. Rock glacier velocities also appear to be correlated with the snow water equivalent of the previous winter's snowpack. Our results demonstrate the ability to use satellite InSAR to monitor rock glaciers over large areas and provide insight into the environmental factors that control their kinematics.
... According to an analysis performed by Barsugli et al., Lake Mead has a 50% percent chance of going dry between 2035 and 2047 if nothing is done to stop the current draw down and evaporation rate of the lake [234]. Other studies on the management of the lake have resulted in the same conclusion [235,236]. These studies have shown the need for new ways to mitigate lake evaporation not only on Lake Mead, but on other lakes in the world, especially those located in arid environments. ...
Article
Distributed generation with solar photovoltaic (PV) technology is economically competitive if net metered in the U.S. Yet there is evidence that net metering is misrepresenting the true value of distributed solar generation so that the value of solar (VOS) is becoming the preferred method for evaluating economics of grid-tied PV. VOS calculations are challenging and there is widespread disagreement in the literature on the methods and data needed. To overcome these limitations, this thesis reviews past VOS studies to develop a generalized model that considers realistic future avoided costs and liabilities. The approach used here is bottom-up modeling where the final VOS for a utility system is calculated. The avoided costs considered are: plant O&M fixed and variable; fuel; generation capacity, reserve capacity, transmission capacity, distribution capacity, and environmental and health liability. The VOS represents the sum of these avoided costs. Each sub-component of the VOS has a sensitivity analysis run on the core variables and these sensitivities are applied for the total VOS. The results show that grid-tied utility customers are being grossly under-compensated in most of the U.S. as the value of solar eclipses the net metering rate as well as two-tiered rates. It can be concluded that substantial future work is needed for regulatory reform to ensure that grid-tied solar PV owners are not unjustly subsidizing U.S. electric utilities. Even without regulatory reform PV is economic, yet to further accelerate PV deployment the economics of PV systems can be improved. One approach to doing this also provides a potential solution to the coupled water–energy–food challenges in land use with the concept of floating photovoltaics or floatovoltaics (FPV). In this thesis, a new approach to FPV is investigated using a flexible crystalline silicon-based FPV module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per unit power. Therefore, foam-based FPV provides a potentially profitable means of reducing water evaporation in the world’s at-risk bodies of fresh water. The case study of Lake Mead found that if 10% of the lake was covered with foam-backed FPV, there would be enough water conserved and electricity generated to service Las Vegas and Reno combined. At 50% coverage, the foam-backed FPV would provide over 127 TWh of clean solar electricity and 633.22 million m3 of water savings, which would provide enough electricity to retire 11% of the polluting coal-fired plants in the U.S. and provide water for over five million Americans, annually. Overall foam-backed FPV thus brings an even greater VOS than conventional PV and indicates that FPV will play a much larger role in our energy future.
... Cette loi place au coeur de ses objectifs la gestion de la demande en eau ; elle définit notamment un programme ambitieux d'économies d'eau que doivent réaliser les différents usagers de la ressource en Arizona, encadré par un système complexe de régulations à l'échelle de l'État (Connall, 1982). 8 Au début des années 2000, pour faire face aux situations de sécheresses récurrentes et dans le contexte de déclin drastique du niveau d'eau dans les principaux réservoirs du bas bassin versant du Colorado (lac Mead et lac Powell) (Barnett et Pierce, 2008), le Bureau of Reclamation (le gestionnaire fédéral de la plupart des grandes infrastructures de l'Ouest étasunien) a mis en place un mécanisme dans lequel, chaque mois, le remplissage du réservoir du lac Mead est estimé pour les deux années suivantes ; si le niveau est inférieur à un certain seuil (328 m), une répartition de crise est déclenchée pour réduire les droits des différents usagers (ADWR, 2015). Même si les villes sont prioritaires, elles doivent désormais reconnaître publiquement qu'elles sont menacées par une réduction de leurs approvisionnements en eau depuis le Colorado 4 . ...
Article
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Our research questions the implementation of rainwater harvesting in Tucson (Arizona) and how it can modify the southwestern United States hydrosocial cycle based on large infrastructures and managed by powerful federal and state agencies. In the context of climate change, the hydrosocial cycle in Tucson is threatened by a water shortage on the Colorado River and has become therefore a controversial issue in the public debate. The implementation of rainwater harvesting in Tucson is the outcome of two different processes: on one hand, it is a “hydrosocial fix” supported by the City to diversify its water portfolio; on the other hand, rainwater harvesting is promoted as a critique towards the current regional hydrosocial cycle. In both cases, the small and local technical systems of rainwater harvesting help materializing the hydrosocial cycle and therefore placing water issues at the heart of the inhabitant’s concerns.
... Over 90% of total water withdrawals in the US are comprised from three economic sectors: thermoelectric generation, irrigation, and public supply (Dieter et al., 2018). Projected increases in population, decreases in water availability, and increases in water temperature could render these sectors highly vulnerable to climate change (Barnett & Pierce, 2008;Elliott et al., 2014;Van Vliet et al., 2012). Recent evidence suggests, however, that water withdrawals in the US has decreased due to advancements in water efficiency and regulation (Dieter et al., 2018;B. ...
Article
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Accurately measuring water use by the economy is essential for developing reliable models of water resource availability. Indeed, these models rely on retrospective analyses that provide insights into shifting human population demands and adaptions to water shortages. However, accurate, methodologically consistent, empirically authentic, and spatiotemporally comprehensive historical datasets for water withdrawals are scarce. Herein, we present a reanalysis of annual resolution (1950–2016) historical data set on irrigation, electric power, and public supply water withdrawal within the conterminous United States (US) at the county‐level, and, for power plants, at the site‐level. To estimate electric power water use, we synthesized a historically comprehensive list of generators and historic patterns in generation across fuels, prime movers, and cooling technologies. Irrigation water use estimation required building a crop‐demand model that utilized historical information on irrigated acreage for crops and golf courses, stage‐specific crop water demand, and climate information. To estimate public water supply use, we developed a random forest model constructed from information on population, infrastructure, climate, and land cover. These estimates generally agree with total county and state water use information provided by the US Geological Survey (USGS) water use circular and estimates generated from independent studies for specific years. However, we also observed discrepancies between our estimates and USGS data that appear to be caused by inconsistencies in the methods used by the USGS's primary data sources at the state level over decades of data collection, highlighting the importance of reanalysis to yield spatiotemporally consistent and intercomparable estimates of water use.
... However, in most cases, such research has focused on how a system might respond to change in the mean values of the environmental parameters and variables, while the effects of change in the variance have seldom been studied (Ridolfi et al., 2011). The stochasticity is caused by disturbance, for example, a sudden decrease in generating capacity or sudden increase of water supply (Barnett and Pierce, 2008;Verma et al., 2012). A deterministic model can reflect the interaction between variables and describe the reality of processes effectively, but it fails to recognize the stochasticity of model structure and parameters. ...
Article
Effects of external disturbances such as the population change on dynamics of water supply, power generation and environmental (WPE) systems have seldom been investigated. Following the WPE nexus profiled in the study of Feng et al. (2016), this study incorporated stochasticity of population, water supply and power generation into the modeling of the dynamical system in the Hehuang region of China, and further quantified resilience measures to understand the system's ability to withstand stochastic disturbances. First, the stochastic differential equations were used to improve the simulation of stochasticity in the WPE nexus. Next, the transient probability distribution functions (pdfs) of system variables, obtained by Monte Carlo simulation, were used to describe the evolutionary process of the system. Finally, the stationary pdfs of variables which reflect stable states of the system were derived to calculate four resilience measures. It is shown that: (1) The system approached a stable state after Year 2400 by calculating the L2 norm of the difference between transient and stationary pdfs. (2) The environmental system was identified as the most vulnerable subsystem because of its long convergence time. (3) The water supply system did not change greatly and it would remain stable at its current low level, i.e., water consumption per capita would be less than 80m³. The method adopted in this study is conducive to avoiding risk and the results provide valuable insights for regional management of a WPE nexus.
... Cette loi place au coeur de ses objectifs la gestion de la demande en eau ; elle définit notamment un programme ambitieux d'économies d'eau que doivent réaliser les différents usagers de la ressource en Arizona, encadré par un système complexe de régulations à l'échelle de l'État (Connall, 1982). 8 Au début des années 2000, pour faire face aux situations de sécheresses récurrentes et dans le contexte de déclin drastique du niveau d'eau dans les principaux réservoirs du bas bassin versant du Colorado (lac Mead et lac Powell) (Barnett et Pierce, 2008), le Bureau of Reclamation (le gestionnaire fédéral de la plupart des grandes infrastructures de l'Ouest étasunien) a mis en place un mécanisme dans lequel, chaque mois, le remplissage du réservoir du lac Mead est estimé pour les deux années suivantes ; si le niveau est inférieur à un certain seuil (328 m), une répartition de crise est déclenchée pour réduire les droits des différents usagers (ADWR, 2015). Même si les villes sont prioritaires, elles doivent désormais reconnaître publiquement qu'elles sont menacées par une réduction de leurs approvisionnements en eau depuis le Colorado 4 . ...
... It is located southeast of the city of Las Vegas and serves as the main water supply for surrounding residents [21]. Driven by climate changes under global warming [22], dramatic decline in Lake Mead's water levels and volumes has been observed in recent years, according to in situ measurements (https://lakemead.water-data.com). Rocks and bare lands dominate Lake Mead's shore based on Google Earth images. ...
Article
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With new Ice, Cloud, and land Elevation Satellite (ICESat)-2 lidar (Light detection and ranging) datasets and classical Landsat imagery, a method was proposed to monitor annual changes of lake water levels and volumes for 35 years dated back to 1980s. Based on the proposed method, the annual water levels and volumes of Lake Mead in the USA over 1984-2018 were obtained using only two-year measurements of the ICESat-2 altimetry datasets and all available Landsat observations from 1984 to 2018. During the study period, the estimated annual water levels of Lake Mead agreed well with the in situ measurements, i.e., the R 2 and RMSE (Root-mean-square error) were 1.00 and 1.06 m, respectively, and the change rates of lake water levels calculated by our method and the in situ data were −1.36 km 3 /year and −1.29 km 3 /year, respectively. The annual water volumes of Lake Mead also agreed well with in situ measurements, i.e., the R 2 and RMSE were 1.00 and 0.36 km 3 , respectively, and the change rates of lake water volumes calculated by our method and in situ data were −0.57 km 3 /year and −0.58 km 3 /year, respectively. We found that the ICESat-2 exhibits a great potential to accurately characterize the Earth's surface topography and can capture signal photons reflected from underwater bottoms up to approximately 10 m in Lake Mead. Using the ICESat-2 datasets with a global coverage and our method, accurately monitoring changes of annual water levels/volumes of lakes-which have good water qualities and experienced significant water level changes-is no longer limited by the time span of the available satellite altimetry datasets, and is potentially achievable over a long-term period.
... Low water level is a symptom of imbalance in the lake water budget, which is driven largely by regional climatic conditions and anthropogenic activities (Gronewold and Stow, 2014;Lai et al., 2014;Ye et al., 2018). Of the anthropogenic activities that are blamed for low water-level conditions, reservoir impoundment upstream is considered to be a critical driver by significantly altering the natural hydrological regimes of downstream rivers and river-connected lakes (Barnett and Pierce, 2008;Gao et al., 2014;He et al., 2018;Liu, Z.J. et al., 2017;Ren et al., 2019;Ye et al., 2018). ...
Article
Water levels of a lake are critical for functions such as navigation, water supply and ecological services; however, the lake water level can be reduced significantly by upstream reservoir refill operations. In this study, the reservoir operating rule curves were redesigned to satisfy the lake's water demand. Variations in lake water level in response to reservoir releases upstream are simulated by using a river-lake model, which is simple and less time-consuming than hydrodynamic models. In the river-lake model, inflow to the lake and outflow from the lake are derived by using a series of regression models of upstream reservoir releases. Then optimization operation model is developed to minimize the lake water-level decline with the restored water level as the benchmark, and to maximize the benefits of hydropower generation simultaneously. The NSGA-II algorithm is used to solve the optimization model, where a moving-average filter is embedded to smooth the operating rule curves. China's Dongting Lake and its upstream reservoir, the Three Gorges Reservoir were selected as a case study. The proposed river–lake model is effective for simulating the lake water level variations, with a Nash–Sutcliffe Efficiency coefficient of 0.94. With the derived optimal operating rule curves, the lake water-level decline caused by conventional reservoir operation during the refill period is reduced by 5.0%, and the hydropower generation and hydropower reliability are improved by 3.9% and 8.3%, respectively. Therefore, the proposed method is an effective tradeoff between lake restoration and enhancing the benefits of hydropower.
Article
The recent California drought has highlighted the potential vulnerability of the state's water management infrastructure to multi-year dry intervals. Due to the high complexity of the network, dynamic storage changes in California reservoirs on a state-wide scale have previously been difficult to model using either traditional statistical or physical approaches. Indeed, although there is a significant line of research on exploring models for single (or a small number of) reservoirs, these approaches are not amenable to a system-wide modeling of the California reservoir network due to the spatial and hydrological heterogeneities of the system. In this work, we develop a state-wide statistical graphical model to characterize the dependencies among a collection 55 major California reservoirs across the state; this model is defined with respect to a graph in which the nodes index reservoirs and the edges specify the relationships or dependencies between reservoirs. We obtain and validate this model in a data-driven manner based on reservoir volumes over the period 2003 – 2016. A key feature of our framework is a quantification of the effects of external phenomena that influence the entire reservoir network. We further characterize the degree to which physical factors (e.g. state-wide Palmer Drought Severity Index (PDSI), average temperature, snow pack) and economic factors (e.g. consumer price index, number of agricultural workers) explain these external influences. As a consequence of this analysis, we obtain a system-wide health diagnosis of the reservoir network as a function of PDSI.
Article
Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906-1999 average, the worst 15-year drought on record. At least one-sixth to one-half (average at one-third) of this loss is due to unprecedented temperatures (0.9°C above the 1906-99 average), confirming model-based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend towards greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model-based temperature projections indicate that continued business-as-usual warming will drive temperature-induced declines in river flow, conservatively -20% by mid-century and -35% by end–century, with support for losses exceeding -30% at mid-century and -55% at end-century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur. This article is protected by copyright. All rights reserved.
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About 58,83 percent of Salatiga population consumes water from PDAM (Peru- sahaan Daerah Air Minum) to fulfill their daily need. The demand for water, which is increasing in line with infrastructure development and economics growth in Salatiga while the availability of water is decreasing, lead to a lack of water in some regions in Salatiga. Therefore, a new policy is needed to solve this problem. Before that, a simulation of the policy is needed because it is not possible to do a direct research on the policy. Thus, this recent study attempts to model the phenomenon of demand for water in Salatiga with dynamics system approach since it can be used for a policy simulation. Based on the simulation result, it is suggested to solve the water scarcity problem by trying to reduce the rate of leaking in water distribution from 26 percent to 5 percent.
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The Middle Rio Grande is a vital source of water for irrigation in the region. Climate change is impacting regional hydrology and is likely to put additional stress on a water supply that is already stretched thin. To gain insight on the hydrologic effects of climate change on reservoir storage, a simple water balance model was used to simulate the Elephant Butte-Caballo reservoir system (Southern New Mexico, USA). The water balance model was forced by hydrologic inputs generated by 97 climate simulations derived from CMIP5 Global Climate Models, coupled to a surface hydrologic model. Results suggest the percentage of years that reservoir releases satisfy agricultural water rights allocations over the next 50 years (2021-2070) will decrease compared to the past 50 years (1971-2020). The modeling also projects an increase in multi-year drought events that hinder reservoir management strategies to maintain high storage levels. In most cases, changes in reservoir inflows from distant upstream snowmelt is projected to have a greater influence on reservoir storage and water availability downstream of the reservoirs, compared to changes in local evaporation and precipitation from the reservoir surfaces.
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Studies addressing the self-sustainability of water bodies are crucial from the perspective of sustainable water resources management. An artificial water body is vulnerable to drastic water level changes resulting from various hydroclimatical and geological factors. It is incumbent therefore to rigorously investigate the effects of these factors in order to assess the response of the water body, consequent to a wide range of scenarios. This study focuses on the self-sustainability of a water body, based on the water budget approach, and taking into account various hydroclimatical and geological factors in the study area. As the available evaporation data shared a very short (~2 years) common time frame with the other variables, evaporation was modelled using regression and artificial neural network models. The study results indicated the water body would be self-sustainable under the extreme climatical and hydrological conditions considered. While seepage exhibited substantial impacts on the storage of the water body, evaporation was found to have only marginal impacts.
Thesis
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As a result of global climate change, during the coming decades less rainfall and higher temperatures are projected for the Brazilian Northeast (NE). Consequently these regional climatic changes could severely impact hydroelectric generation in the NE as well as influence solar and wind power potential. The ongoing drought in the Brazilian NE region has caused hydroelectric generation to decline substantially during the last 5 years and in 2016 hydroelectricity only supplied 25% of the NE’s total demand. In contrast, wind power supplied 30% of demand and is expected to generate 55-60% of the NE’s electricity supply by 2020. Therefore, this paper is focused on both short term forecasting and long-term projections of renewable energy generation and resource availability. It also explores the economic, environmental and technical feasibility of renewable energy integration in the NE region of Brazil. First, the long-term impacts of climate change on the NE region’s hydroelectric and wind energy production are analysed. Particular attention is paid to the long-term projections of annual rainfall and streamflow in the São Francisco basin which could decline by approximately 47% and 80%, respectively, by 2050. On the other hand, wind energy potential is projected to increase substantially during the same period. This thesis also estimates the economic, social, and environmental viability of renewable and non-renewable generation technologies in Brazil. The Levelised Cost of Electricity (LCOE) including externalities is calculated for several different case study power plants, the majority of which are located in the Brazilian NE. It was found that wind power becomes the cheapest generation technology in the NE region, once all externality and transmission line costs are taken into consideration. The LCOE for the entire Northeast’s generation matrix is calculated for various configurations, including scenarios in which hydroelectric generation is restricted due to drought conditions. It was concluded that a generation mix in which wind power replaces all fossil fuel generation by 2020, could feasibly reduce the overall LCOE in the region by approximately 46% and substantially decrease CO2eq emissions. Two different methods are used to examine the limits of integrating high penetrations of variable renewable generation technologies into a power system with a large proportion of hydroelectric capacity. In the first method existing wind generation data from 16 wind farms is extrapolated in time and space, while the second method uses a numerical weather prediction model to simulate future wind energy generation in the NE region. Considering the minimum generation requirements of the São Francisco’s hydroelectric dams, the maximum wind energy penetration in the NE region is estimated to be approximately 50% before significant amounts of energy would need to be curtailed or exported to other Brazilian regions. Finally, this thesis reviews additional literature on energy storage and the impact of large scale variable renewable energy integration on grid stability and power quality. It was found that there are several existing technologies such as power factor and voltage regulation devices that can resolve these issues.
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Water managers are increasingly interested in better understanding and planning for projected resource impacts from climate change. In this management-guided study, we use a very large suite of synthetic climate scenarios in a statistical modeling framework to simultaneously evaluate how (1) average temperature and precipitation changes, (2) initial basin conditions, and (3) temporal characteristics of the input climate data influence water-year flow in the Upper Colorado River. The results here suggest that existing studies may underestimate the degree of uncertainty in future streamflow, particularly under moderate temperature and precipitation changes. However, we also find that the relative severity of future flow projections within a given climate scenario can be estimated with simple metrics that characterize the input climate data and basin conditions. These results suggest that simple testing, like the analyses presented in this paper, may be helpful in understanding differences between existing studies or in identifying specific conditions for physically based mechanistic modeling. Both options could reduce overall cost and improve the efficiency of conducting climate change impacts studies.
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Rock glaciers are a prominent component of many alpine landscapes and constitute a significant water resource in some arid mountain environments. Here, we employ satellite-based interferometric synthetic aperture radar (InSAR) to identify and monitor active rock glaciers in the Uinta Mountains (Utah, USA), an area of ~10,000 km2. We used mean velocity maps to generate an inventory for the Uinta Mountains containing 255 active rock glaciers. Active rock glaciers are 10.8 ha in area on average, and located at a mean elevation of 3290 m, where mean annual air temperature is 0.12 °C. The mean line-of-sight (LOS) velocity for the inventory is 2.52 cm/yr, but individual rock glaciers have LOS velocities ranging from 0.88 to 5.26 cm/yr. To search for relationships with climatic drivers, we investigate the time-dependent motion of three rock glaciers over the summers of 2016–2019. Time series analysis suggests that rock glacier motion has a significant seasonal component, with motion that is more than 5 times faster during the late summer compared to rest of the year. Rock glacier velocities also appear to be correlated with the snow-water equivalent of the previous winter's snowpack. These results demonstrate the ability to use satellite InSAR to monitor rock glaciers over large areas and provide insight into the environmental factors that control their kinematics.
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The Colorado River basin is a fundamentally important river for society, ecology and energy in the United States. Streamflow estimates are often provided using modeling tools which rely on uncertain parameters; sensitivity analysis can help determine which parameters impact model results. Despite the fact that simulated flows respond to changing climate and vegetation in the basin, parameter sensitivity of the simulations under climate change has rarely been considered. In this study, we conduct a global sensitivity analysis to relate changes in runoff, evapotranspiration, snow water equivalent and soil moisture to model parameters in the Variable Infiltration Capacity (VIC) hydrologic model. We combine global sensitivity analysis with a space-filling Latin Hypercube sampling of the model parameter space and statistical emulation of the VIC model to examine sensitivities to uncertainties in 46 model parameters following a variance-based approach. We find that snow-dominated regions are much more sensitive to uncertainties in VIC parameters. Although baseflow and runoff changes respond to parameters used in previous sensitivity studies, we discover new key parameter sensitivities. For instance, changes in runoff and evapotranspiration are sensitive to albedo, while changes in snow water equivalent are sensitive to canopy fraction and Leaf Area Index (LAI) in the VIC model. It is critical for improved modeling to narrow uncertainty in these parameters through improved observations and field studies. This is important because LAI and albedo are anticipated to change under future climate and narrowing uncertainty is paramount to advance our application of models such as VIC for water resource management.
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Over the years, the Colorado River has become inadequate for development due to natural factors and human activities. The hydroelectric facilities in Lake Mead and Lake Powell are also not fully utilized. Downstream, Mexico is also involved in the competition for water. The resulting allocation of water and electricity resources and sustainable development are hanging over our heads and waiting to be solved. In this work, a simplified Penstock Dam model and a Distance Decay model are designed based on publicly available data, and a Multi-attribute Decision model for hydropower based on the Novel Technique for Order Preference by Similarity to an Ideal Solution method is proposed. In addition, an Improved Particle Swarm Optimization model is proposed by adding oscillation parameters. The Mexican equity problem is also explored. The theoretical results show that the average error of the Penstock Dam model is 3.2%. The minimum water elevation requirements for Lake Mead and Lake Powell are 950 ft and 3460 ft, respectively; they will not meet demand in 2026 and 2027 without action, and they will require the introduction of and water in 2027 and 2028, respectively. The solution shows that the net profit for the United States is greatest when 38.6% of the additional water is used for general purposes, 47.5% is used for power generation, and the rest flows to Mexico. A final outlook on the sustainability of the Colorado River is provided.
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Drought events are increasing worldwide. Socio-economic drought is the least investigated type of drought, and is the only type for which water demand is taken into consideration. In this research, socio-economic drought was studied in Lake Mead, USA, using a multivariate standardized water scarcity index (MSWSI) over the period 1990–2014, combining two water scarcity indices based on time series of inflow, outflow, reservoir storage, and water demand. The inflow and outflow were determined from stream gage data, reservoir storage from lake level data; and demand was based on water pumped by the Southern Nevada Water Authority. Missing observations in input stream gage data were filled through regression modeling. The results indicate that Lake Mead has been in socio-economic drought since 2000, with the most severe drought occurring between 2006 and 2012, and the highest intensity drought in April–July 2014. The Lake Mead droughts revealed through the MSWSI are consistent with those reported in US Drought Monitor (USDM) products. The temporal behavior of MSWSI provides an insight into the socio-economic effects of droughts not captured by USDM products.
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Riparian ecosystems are shaped by interactions among streamflow, plants, and physical processes. Sustaining functioning riparian ecosystems in the face of climate change, growing human demands for water, and increasing water scarcity requires improved understanding of the sensitivity of riparian ecosystems to shifts in flow regimes and associated adaptive management strategies. We applied projected future flow regimes to an ecogeomorphic model of riparian and channel response to evaluate these interactions. We tested the hypothesis that components of the riparian ecosystem vary in their vulnerabilities to shifts in flow attributes and that changes in the representation of functional groups of plants result from interactions between ecological and physical drivers. Using the Yampa and Green Rivers in northwestern Colorado as our test system, we investigated ecogeomorphic response to (1) synthetic flow regimes representing continuous changes from baseline flows; and (2) future flow scenarios that incorporate changing climate, demand, and water-resource projects. For this region, we showed that riparian plant presence, composition, and cover are highly sensitive to the high flows that occur early in the growing season, but that shifts to low flows are also important, especially for determining the functional diversity of a riparian community. Future flow regimes are likely to induce vegetation encroachment on lower channel surfaces and to increase plant cover, which will be dominated by fewer functional groups. In particular, we predict a decrease in some mesic plants (shrubs and tall herbs) and an increase in presence and cover of late-seral, xeric shrubs, most of which are non-native species. Managing for high flows that occur early in the growing season must complement maintenance of adequate baseflows to maintain ecosystem functioning in the face of hydrologic alterations induced by climate change and human water demand.
Chapter
Water resources management must overcome the dilemma between the timing of water demands and availability. Groundwater resources are often tapped to fulfill demands during reduced surface water availability or in regions without access to surface water, resulting in a global phenomenon of groundwater depletion as groundwater withdrawals exceed recharge. Sustainable groundwater management requires approaches to assess the influence of adaptive management on the evolution of groundwater systems. In this chapter, we evaluate the spatiotemporal groundwater dynamics in the Coachella Valley of California to assess relationships between groundwater management and use. Our results illustrate spatially limited effects of adaptive management that occur against a setting of long-term groundwater depletion, highlighting the need to employ integrative and diverse adaptive management schemes to achieve sustainable groundwater management.
Chapter
The Parasol Club is a student-run, collaborative group focusing on sustainable resource use at the University of Arizona (UA), especially rainwater harvesting. The group’s fundamental idea is that, as a land-grant university in an arid environment, UA should serve as a learning laboratory for the development and demonstration of techniques for sustainable use of water and energy. Parasol’s success is due largely to its collaborative model in which students work closely with facilities staff, faculty, and administrators to identify sites, gather materials and labor, and bring projects to fruition. Completed projects serve as a testament to the effectiveness of the collaborative model. As the group has demonstrated the power of institutional collaboration at the university, its circle has widened to include members of several academic departments, additional facilities staff, and university administrators. New campus projects are planned, and the group has extended its reach to work with Tucson primary schools and neighborhood organizations on rainwater harvesting projects. This paper discusses Parasol’s model as an example for collaborative infrastructure and project development at an institutional level.
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Rapid social and economic development results in increased demand for water resources. This can lead to the unsustainable development and exploitation of water resources which in turn causes significant environmental problems. Conventional water resource management approaches, such as supply and demand management strategies, frequently fail to restore regional water balance. This paper introduces the concept of water consumption balance, the balance between actual evapotranspiration (ET) and target ET, and establishes a framework to realize regional water balance. The framework consists of three stages: (1) determination of target ET and actual ET; (2) quantification of the water-saving requirements for the region; and (3) reduction of actual ET by implementing various water saving management strategies. Using this framework, a case study was conducted for Guantao County, China. The SWAT model was utilized to aid in the selection of the best water saving management strategy by comparing the ET of different irrigation methods and crop pattern adjustments. Simulation results revealed that determination of SWAT model parameters using remote sensing ET is feasible and that the model is a valuable tool for ET management. Irrigation was found to have a greater influence on the ET of winter wheat as compared to that of maize, indicating that reduction in winter wheat cultivation is the most effective way to reduce regional ET. However, the effect of water-saving irrigation methods on the reduction of ET was not obvious. This indicates that it would be difficult to achieve regional ET reduction using water-saving irrigation methods only. Furthermore, selecting the best water saving management strategy by relying solely on the amount of reduced ET was insufficient, because it ignored the impact of water conservation measures on the livelihood of the agricultural community. Incorporating these considerations with our findings, we recommend changing the current irrigation method to sprinkler irrigation and replacing 20% of the winter wheat-maize cultivated area with cotton, as the best strategy to achieve water balance in the study area.
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Much has been learned about Colorado River hydrology since the severe sustained drought study in 1995. We summarize our updated understanding of plausible future drought conditions by considering historical flows, tree‐ring reconstructions, and climate change. We focus on natural streamflow at Lees Ferry, the primary metric used to quantify the runoff in the Colorado River Basin. We identify drought periods using historical records and tree‐ring reconstructed streamflow at Lees Ferry, which we then use to characterize potential future droughts. Resampling from past drought periods generates plausible future conditions to consider during planning. We produced three drought scenarios, each comprising 100 streamflow sequences to be used as input to systems operation and management models. We used analysis of the duration‐severity and cumulative deficit relative to the mean natural flow to evaluate droughts and drought simulations and show that the current millennium drought that started in 2000 has an average flow far less than the historical record. However, the flows reconstructed from tree rings or future flows projected from climate models indicate that even more severe droughts are possible. When used as input to the Colorado River Simulation System the drought scenarios developed indicate considerable periods when Lake Powell falls below its hydropower penstocks, indicating a need to rethink management and operation of these reservoirs during these critical conditions.
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Water availability on the continents is important for human health, economic activity, ecosystem function and geophysical processes. Because the saturation vapour pressure of water in air is highly sensitive to temperature, perturbations in the global water cycle are expected to accompany climate warming. Regional patterns of warming-induced changes in surface hydroclimate are complex and less certain than those in temperature, however, with both regional increases and decreases expected in precipitation and runoff. Here we show that an ensemble of 12 climate models exhibits qualitative and statistically significant skill in simulating observed regional patterns of twentieth-century multidecadal changes in streamflow. These models project 10-40% increases in runoff in eastern equatorial Africa, the La Plata basin and high-latitude North America and Eurasia, and 10-30% decreases in runoff in southern Africa, southern Europe, the Middle East and mid-latitude western North America by the year 2050. Such changes in sustainable water availability would have considerable regional-scale consequences for economies as well as ecosystems.
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Implications of 21st century climate change on the hydrology and water resources of the Colorado River basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950–1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into period 1 (2010–2039), period 2 (2040–2069), and period 3 (2070–2099). The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4°C for periods 1–3, and for the B1 scenario from 1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean changes ranging from −1 to −2 percent for the A2 scenario, and from +1 to −1 percent for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived 1 April snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38 percent for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff reductions of −1, −6, and −11 percent for the A2 ensembles, and 0, −7, and −8 percent for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin (mandated by the Colorado River Compact) were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20% by period 3 in for both emissions scenarios, and the average shortage increased to a maximum of 3.7 BCM/yr for the period 3 A2 ensemble average. Hydropower output was reduced in the ensemble mean for all time periods and both emissions scenarios.
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Today, hydrologic research and modeling depends largely on climatological inputs, whose physical and statistical behavior are the subject of many debates in the scientific community. A relevant ongoing discussion is focused on long-term persistence (LTP), a natural behavior identified in several studies of instrumental and proxy hydroclimatic time series, which, nevertheless, is neglected in some climatological studies. LTP may reflect a long-term variability of several factors and thus can support a more complete physical understanding and uncertainty characterization of climate. The implications of LTP in hydroclimatic research, especially in statistical questions and problems, may be substantial but appear to be not fully understood or recognized. To offer insights on these implications, we demonstrate by using analytical methods that the characteristics of temperature series, which appear to be compatible with the LTP hypothesis, imply a dramatic increase of uncertainty in statistical estimation and reduction of significance in statistical testing, in comparison with classical statistics. Therefore we maintain that statistical analysis in hydroclimatic research should be revisited in order not to derive misleading results and simultaneously that merely statistical arguments do not suffice to verify or falsify the LTP (or another) climatic hypothesis.
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The total amount of water stored in a river basin affects streamflow at various timescales and defines the river basin's response to atmospheric forcing. For example, spring runoff in mountainous midlatitude catchments depends on winter snowpack, and groundwater storage sustains flow during dry periods. An accurate estimation of terrestrial water storage (TWS) is thus paramount for improved water management. Direct determination of TWS is difficult due to insufficient in situ data on space-time variability of hydrologic stores (snow, soil moisture, groundwater) and fluxes (precipitation, evapotranspiration). However, alternative methods using new data sets show great potential to improve the estimation of intra-annual and interannual TWS dynamics.
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1] New tree-ring records of ring-width from remnant preserved wood are analyzed to extend the record of reconstructed annual flows of the Colorado River at Lee Ferry into the Medieval Climate Anomaly, when epic droughts are hypothesized from other paleoclimatic evidence to have affected various parts of western North America. The most extreme low-frequency feature of the new reconstruction, covering A.D. 762-2005, is a hydrologic drought in the mid-1100s. The drought is characterized by a decrease of more than 15% in mean annual flow averaged over 25 years, and by the absence of high annual flows over a longer period of about six decades. The drought is consistent in timing with dry conditions inferred from tree-ring data in the Great Basin and Colorado Plateau, but regional differences in intensity emphasize the importance of basin-specific paleoclimatic data in quantifying likely effects of drought on water supply.
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The Hurst phenomenon, which characterises hydrological and other geophysical time series, is formulated and studied in an easy manner in terms of the variance and autocorrelation of a stochastic process on multiple temporal scales. In addition, a simple explanation of the Hurst phenomenon based on the fluctuation of a hydrologic process upon different temporal scales is presented. The stochastic process that was devised to represent the Hurst phenomenon, i.e. the fractional Gaussian noise, is also studied on the same grounds. Based on its studied properties, three simple and fast methods to generate fractional Gaussian noise or good approximations of it are proposed. Le phénomène Hurst et le bruit fractionnel gaussien rendus faciles dans leur utilisation Résumé. On formule et étudie d'une manière simple le phénomène Hurst, qui caractérise les séries chronologiques en hydrologie et en géophysique, en termes de la variance et deì autocorrélationun processus stochastique considéré dans des échelles temporelles multiples. De plus, on présente une explication simple du phénomène Hurst sur la base de la fluctuationun processus hydrologique dans des échelles temporelles multiples. On étudie aussi d'une manière analogue le bruit fractionnel gaussien qui constitue le processus stochastique construit pour représenter le phénomène Hurst. Se basant sur les propriétés étudiées de ce processus, on propose trois méthodes simples et rapides qui permettent de générer du bruit fractionnel gaussien ou de bonnes approximations de ceci.
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1] The high demand for water, the recent multiyear drought (1999 – 2007), and projections of global warming have raised questions about the long-term sustainability of water supply in the southwestern United States. In this study, the potential effects of specific levels of atmospheric warming on water-year streamflow in the Colorado River basin are evaluated using a water-balance model, and the results are analyzed within the context of a multi-century tree-ring reconstruction (1490– 1998) of streamflow for the basin. The results indicate that if future warming occurs in the basin and is not accompanied by increased precipitation, then the basin is likely to experience periods of water supply shortages more severe than those inferred from the long-term historical tree-ring reconstruction. Furthermore, the modeling results suggest that future warming would increase the likelihood of failure to meet the water allocation requirements of the Colorado River Compact.
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The potential effects of climate change on the hydrology and water resources of the Colorado River basin are assessed by comparing simulated hydrologic and water resources scenarios derived from downscaled climate simulations of the U.S. Department of Energy/National Center for Atmospheric Research Parallel Climate Model (PCM) to scenarios driven by observed historical (1950–1999) climate. PCM climate scenarios include an ensemble of three 105-year future climate simulations based on projected `business-as-usual'(BAU) greenhouse gas emissions and a control climate simulation based on static 1995 greenhouse gas concentrations. Downscaled transient temperature and precipitation sequences were extracted from PCM simulations, and were used to drive the Variable Infiltration Capacity (VIC) macroscale hydrology model to produce corresponding streamflow sequences. Results for the BAU scenarios were summarized into Periods 1, 2, and 3 (2010–2039,2040–2069, 2070–2098). Average annual temperature changes for the Colorado Riverbasin were 0.5 °C warmer for control climate, and 1.0, 1.7, and 2.4 °C warmer for Periods 1–3, respectively, relative to the historicalclimate. Basin-average annual precipitation for the control climate was slightly(1
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The article presents the authors' claim that the concept of stationarity, the idea that the systems for management of water fluctuate within an unchanging domain of variability, is dead. According to the authors, the idea of stationarity had ceased due to the substantial anthropogenic change of the Earth's climate which alters the means and extremes of precipitation, evapotranspiration and rates of discharge of rivers affecting water cycle. They denote that the rational planning framework developed by Harvard University's Water Program helps address the changing climate to manage water system.
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The Lo’s modified rescaled adjusted range test (R/S test) (Lo, 1991), GPH test (Geweke and Porter-Hudak, 1983) and two approximate maximum likelihood estimation methods, i.e., Whittle’s estimator (W-MLE) and another one implemented in S-Plus (S-MLE) based on the algorithm of Haslett and Raftery (1989) are evaluated through intensive Monte Carlo simulations for detecting the existence of longmemory. It is shown that it is difficult to find an appropriate lag q for Lo’s test for different short-memory autoregressive (AR) and fractionally integrated autoregressive and moving average (ARFIMA) processes, which makes the use of Lo’s test very tricky. In general, the GPH test outperforms the Lo’s test, but for cases where a strong short-range dependence exists (e.g., AR(1) processes with φ=0.95 or even 0.99), the GPH test gets useless, even for time series of large
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Implications of 21st century climate change on the hydrology and water resources of the Colorado River Basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950?1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into three periods: 2010?2039, 2040?2069, and 2070?2099. The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4°C for periods 1?3, and for the B1 scenario from 1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean changes ranging from ?1 to ?2% for the A2 scenario, and from +1 to ?1% for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived April 1 snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38% for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff changes of ?1, ?6, and ?11% for the A2 ensembles, and 0, ?7, and ?8% for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage and average hydropower production generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20% by period 3 for both emissions scenarios.
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How anthropogenic climate change will affect hydroclimate in the arid regions of southwestern North America has implications for the allocation of water resources and the course of regional development. Here we show that there is a broad consensus among climate models that this region will dry in the 21st century and that the transition to a more arid climate should already be under way. If these models are correct, the levels of aridity of the recent multiyear drought or the Dust Bowl and the 1950s droughts will become the new climatology of the American Southwest within a time frame of years to decades.
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Observations have shown that the hydrological cycle of the western United States changed significantly over the last half of the 20th century. We present a regional, multivariable climate change detection and attribution study, using a high-resolution hydrologic model forced by global climate models, focusing on the changes that have already affected this primarily arid region with a large and growing population. The results show that up to 60% of the climate-related trends of river flow, winter air temperature, and snow pack between 1950 and 1999 are human-induced. These results are robust to perturbation of study variates and methods. They portend, in conjunction with previous work, a coming crisis in water supply for the western United States.
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Changes in regional temperature and precipitation expected to occur as a result of the accumulation of greenhouse gases may have significant impacts on water resources. We use a conceptual hydrologic model, developed and operated by the National Weather Service, to study the sensitivity of surface runoff in several sub-basins of the Colorado River to these changes. Increases in temperature of 2°C decrease mean annual runoff by 4–12%. A temperature increase of 4°C decreases mean annual runoff by 9–21%. Increases or decreases in annual precipitation of 10–20% result in corresponding changes in mean annual runoff of approximately 10–20%. For the range of scenarios studied, these results suggest that runoff in the basin is somewhat more sensitive to changes in precipitation than to changes in temperature. Seasonal changes were also observed, with peak runoff shifting from June to April or May. Fall and winter flows generally increase, whereas spring and summer flows decrease in most of the scenarios studied. These changes are attributed to an increase of the ratio of rain to snow and to a higher snowline. Although these results suggest that streamflow in the Colorado Basin is less sensitive to climatic changes than previous statistical studies have indicated, the magnitude of possible changes is nonetheless sufficiently great to have significant environmental, economic, and political implications.
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The paper surveys the literature in the two related areas of riverflow modelling and reservoir storage modelling over the past 100 years. In the area of riverflow modelling it describes the salient features of hydrological time-series and shows how hydrologists have tackled the problem of model formulation. In the area of storage theory, it describes how mathematicians have tackled this problem making use of the theory of stochastic processes.
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The indexed sequential hydrologic modeling (ISM) methodology is utilized by the Western Area Power Administration as the basis for risk-based estimation of project-dependable hydropower capacity for several federally owned/operated projects. ISM is a technique based on synthetic generation of a series of overlapping short-term inflow sequences obtained directly from the historical record. The validity of ISM is assessed through application to the complex multireservoir hydropower system of the Colorado River basin for providing risk estimates associated with determination of reliable hydrogeneration capacity. Performance of ISM is compared with results from stochastically generated streamflow input data to the Colorado River Simulation System (CRSS). Statistical analysis and comparison of results are based on monthly power capacity, energy generation, and downstream water deliveries. Results indicate that outputs generated from ISM synthetically generated sequences display an acceptable correspondence with those obtained from stochastically generated hydrologic data for the Colorado River Basin.
Article
The impacts of a severe sustained drought on Colorado River system water resources were investigated by simulating the physical and institutional constraints within the Colorado River Basin and testing the response of the system to different hydrologic scenarios. Simulations using Hydrosphere's Colorado River Model compared a 38-year severe sustained drought derived from 500 years of reconstructed streamflows for the Colorado River basin with a 38-year streamflow trace extracted from the recent historic record. The impacts of the severe drought on streamflows, water allocation, storage, hydropower generation, and salinity were assessed. Estimated deliveries to consumptive uses in the Upper Basin states of Colorado, Utah, Wyoming, New Mexico, and northern Arizona were heavily affected by the severe drought, while the Lower Basin states of California, Nevada, and Arizona suffered only slight shortages. Upper Basin reservoirs and streamflows were also more heavily affected than those in the Lower Basin by the severe drought. System-wide, total hydropower generation was 84 percent less in the drought scenario than in the historical stream-flow scenario. Annual, flow-weighted salinity below Lake Mead exceeded 1200 ppm for six years during the deepest portion of the severe drought. The salinity levels in the historical hydrology scenario never exceeded 1100 ppm.
Article
We present power spectra of time-series data for tree ring width chronologies, atmospheric temperatures, river discharges and precipitation averaged over hundreds of stations worldwide. The average power spectrum S for each of these phenomena is found to have a power-law dependence on frequency with exponent . An advection-diffusion model of the vertical transport of heat and water vapor in the atmosphere is presented as a first-order model of climatic and hydrological variability. The model generates variability with the observed spectrum. The model is validated with a correlation analysis of temperature and water vapor concentration measurements from the TIROS operational vertical sounder (TOVS). Drought frequency analyses based on synthetic lognormal streamflows with the above power spectrum are presented. We show that the presence of long memory as implied by the power-law power spectrum has a significant effect on the likelihood of extended droughts compared with the drought hazard implied from standard autoregressive models with short memory.
Sustainable use of water in the lower Colorado River Basin Pac
  • J S Morrison
  • P Postel
  • Gleick
The Colorado Basin and climate change, EPA 230-R-93-009
  • L Nash
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The Colorado Basin and climate change, EPA 230-R-93-009, Policy, Plann. and Eval Indexed sequential hydro-logic modeling for hydropower capacity estimates
  • L Nash
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Nash, L., and P. Gleick (1993), The Colorado Basin and climate change, EPA 230-R-93-009, Policy, Plann. and Eval., Environ. Prot. Agency, Washington, D. C. Ouarda, T., D. Labadie, and D. Frontere (1997), Indexed sequential hydro-logic modeling for hydropower capacity estimates, J. Am. Water Resour. Assoc., 33(6), 1 – 13.
Waste not, want not: The potential for urban water conservation in California Impacts of a severe sustained drought on Colorado River water resources, Water Re-sour
  • P H Gleick
  • D Haasz
  • C Henges-Jeck
  • V Srinivasan
  • G Wolf
  • K K Cushing
  • A Mann
Gleick, P. H., D. Haasz, C. Henges-Jeck, V. Srinivasan, G. Wolf, K. K. Cushing, and A. Mann (2003), Waste not, want not: The potential for urban water conservation in California, 176 pp., Pac. Inst., Oakland, Calif. Harding, B. L., T. B. Sangoyomi, and E. A. Payton (1995), Impacts of a severe sustained drought on Colorado River water resources, Water Re-sour. Bull., 31, 815 – 824.
Sustainable use of water in the lower Colorado River Basin The sensitivity of stream flow in the Color-ado Basin to climatic changes
  • J Morrison
  • S Postel
  • P Gleick
Morrison, J., S. Postel, and P. Gleick (1996), Sustainable use of water in the lower Colorado River Basin, Pac. Inst., Oakland, Calif. Nash, L., and P. Gleick (1991), The sensitivity of stream flow in the Color-ado Basin to climatic changes, J. Hydrol., 125, 221 – 241.
Letter to regional director, lower Colorado region re
  • J Weisheit
  • M Harrington-Deis
  • Living Rivers
  • Moab
  • Utah
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  • D W Barnett
  • Pierce Barnett And Pierce: When Will Lake Mead
  • Go
Weisheit, J., and M. Harrington (2007), Letter to regional director, lower Colorado region re-DEIS, Living Rivers, Moab, Utah. ÀÀ ÀÀ ÀÀ À À ÀÀ ÀÀ À À À À À À À À À À À À À À À À T. P. Barnett and D. W. Pierce, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037, USA. (tbarnett-ul@ ucsd.edu) 10 of 10 W03201 BARNETT AND PIERCE: WHEN WILL LAKE MEAD GO DRY? W03201
Indexed sequential hydrologic modeling for hydropower capacity estimates
  • T Ouarda
  • D Labadie
  • D Frontere
Letter to regional director Living Rivers
  • J M Weisheit
  • Harrington
Waste not, want not: The potential for urban water conservation in California 176 Pac
  • P H D Gleick
  • C Haasz
  • V Henges-Jeck
  • G Srinivasan
  • K K Wolf
  • A Cushing
  • Mann
The Colorado Basin and climate change EPA 230 R 93 009 Policy
  • L P Nash
  • Gleick