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Climatization-negligent attribution of Great Salt Lake desiccation: A comment on Meng (2019)
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Abstract
Meng (2019) reviewed data on Great Salt Lake (Utah) and concluded falsely that climate changes, especially local warming and extreme precipitation events are primarily responsible for the elevation changes in this, and other saline lakes worldwide. Meng is correct that climatically influenced variation of net inflows contribute to huge swings in the elevation of Great Salt Lake (GSL) and other endorheic lakes. Although droughts and wet cycles have caused lake elevation changes of over 4.5 m, they have not caused a significant long-term change in GSL stage. Meng also suggests that a 1.4°C rise in air temperature and concomitant increase in the lake's evaporative loss is an important reason for the lake's decline. Although Meng provided no quantitative explanation for this, we calculate that a 1.4°C rise may have caused only a 0.1 m decrease in lake level. However, since 1847 the lake has declined 3.6 m and lake area has decreased by ~50%, despite there being no significant change in precipitation (p = 0.52) and a slight increase, albeit insignificant, in river flows above irrigation diversions (p = 0.085). In contrast, persistent water extraction for agriculture and other uses beginning in 1847 now decreases water flows below diversions by 39%. Estimates of consumptive water use primarily for irrigated agriculture in the GSL watershed suggest that approximately 85% (2500 km 2) of the reduced lake area can be attributed to human water consumption. Meng's failure to calculate a water budget for the lake that included extensive water withdrawals misled him to focus instead on climate change as a causal factor for the decline. Stable stream flows in GSL's headwaters, inadequate temperature increase to explain the extent of its observed desiccation, stable long-term precipitation, and the magnitude of increased water consumption from GSL-together demonstrate conclusively that climatic factors are secondary to human alterations to GSL and its watershed. Climatization, in which primarily non-climatic processes are falsely attributed to climatic factors, is a threat to the credibility of hydrological science. Despite a recent suggestion to the contrary, pressure to support Earth's rising human population-in the form of increasing consumption of water in water-limited regions, primarily to support irrigated agriculture-remains the leading driver of desiccation of inland waters within Earth's water-limited regions.
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Plain Language Summary
Past studies have shown that global evapotranspiration has been increasing between the 1980s and 2000 and has been decreasing since 2000. These studies were done assuming surface water body areas (i.e. lakes and rivers) are constant throughout their study periods. However, surface water bodies on earth are changing constantly. Over the past 30 years, more than 90000 km3 of permanent water has disappeared while over 180000 km3 has emerged elsewhere. The conversion between land and water introduces a significant change of evapotranspiration from the earth's surface which has been neglected by past studies. Here, we quantify this change in evapotranspiration caused by such land‐water conversion to reduce the uncertainties in the estimation of global evapotranspiration trend. We find an increase in evapotranspiration caused by land‐water conversion of 30.38 {plus minus} 15.51 km3/yr between 1984‐1999 and 2000‐2015. The magnitude of this change is comparable to that of annual global evapotranspiration change assuming stationary surface water areas. Thus, surface water dynamics can lead to considerable changes in global evapotranspiration and should not be neglected in future global water budget studies.
A viewpoint of a temporal trend with an extremely changing point analysis is proposed to analyze and characterize the so-called current declines of the world’s saline lakes. A temporal trend of a hydrological or climate variable is statistically tested by regressing it against time; if the regression is statistically significant, an ascending or declining trend exists. The extremely changing points can be found out by using the mean of a variable, adding or subtracting two times of its standard deviation (SD) for extremely high values and extremely low values, respectively. Applying the temporal trend method to the Great Salt Lake’s (GSL) relationship between its surface levels and precipitation/temperature in the last century, we conclude that climate changes, especially local warming and extreme weather including both precipitation and temperature, drive the dynamics (increases and declines) of the GSL surface levels.
A novel quantitative assessment of late Holocene precipitation in the Levant is presented, including mean and variance of annual precipitation and their trends. A stochastic framework was utilized and allowed, possibly for the first time, linking high-quality, reconstructed rises/declines in Dead Sea levels with precipitation trends in its watershed. We determined the change in mean annual precipitation for 12 specific intervals over the past 4500 yr, concluding that: (1) the twentieth century was substantially wetter than most of the late Holocene; (2) a representative reference value of mean annual precipitation is 75% of the present-day parameter; (3) during the late Holocene, mean annual precipitation ranged between −17 and +66% of the reference value (−37 to +25% of present-day conditions); (4) the driest intervals were 1500–1200 BC and AD 755–890, and the wettest intervals were 2500–2460 BC, 130–40 BC, AD 350–490, and AD 1770–1940; (5) lake-level rises and declines probably occurred in response to trends in precipitation means and are less likely to occur when precipitation mean is constant; (6) average trends in mean annual precipitation during intervals of ≥200 yr did not exceed 15 mm per decade. The precipitation trends probably reflect shifts in eastern Mediterranean cyclone tracks.
Correction to: Nature Geoscience https://doi.org/10.1038/s41561-018-0265-7, published online 30 November 2018.
In the version of this Article originally published, in the section ‘Defining endorheic regions’ in Methods, the sentence starting “These watersheds were aggregated…” contained the phrase “(~100,000 thousand km2)”; this should have read (~100,000 km2) and has now been amended.
The rapid shrinkage of Lake Urmia, one of the world's largest saline lakes located in northwestern Iran, is a tragic wake-up call to revisit the principles of water resources management based on the socio-economic and environmental dimensions of sustainable development. The overarching goal of this paper is to set a framework for deriving dynamic, climate-informed environmental inflows for drying lakes considering both meteorological/climatic and anthropogenic conditions. We report on the compounding effects of meteorological drought and unsustainable water resource management that contributed to Lake Urmia's contemporary environmental catastrophe. Using rich datasets of hydrologic attributes, water demands and withdrawals, as well as water management infrastructure (i.e. reservoir capacity and operating policies), we provide a quantitative assessment of the basin's water resources, demonstrating that Lake Urmia reached a tipping point in the early 2000s. The lake level failed to rebound to its designated ecological threshold (1274 m above sea level) during a relatively normal hydro-period immediately after the drought of record (1998-2002). The collapse was caused by a marked overshoot of the basin's hydrologic capacity due to growing anthropogenic drought in the face of extreme climatological stressors. We offer a dynamic environmental inflow plan for different climate conditions (dry, wet and near normal), combined with three representative water withdrawal scenarios. Assuming effective implementation of the proposed 40% reduction in the current water withdrawals, the required environmental inflows range from 2900 million cubic meters per year (mcm yr⁻¹) during dry conditions to 5400 mcm yr⁻¹ during wet periods with the average being 4100 mcm yr⁻¹. Finally, for different environmental inflow scenarios, we estimate the expected recovery time for re-establishing the ecological level of Lake Urmia.
Freshwater availability is changing worldwide. Here we quantify 34 trends in terrestrial water storage observed by the Gravity Recovery and Climate Experiment (GRACE) satellites during 2002-2016 and categorize their drivers as natural interannual variability, unsustainable groundwater consumption, climate change or combinations thereof. Several of these trends had been lacking thorough investigation and attribution, including massive changes in northwestern China and the Okavango Delta. Others are consistent with climate model predictions. This observation-based assessment of how the world's water landscape is responding to human impacts and climate variations provides a blueprint for evaluating and predicting emerging threats to water and food security.
Lake evaporation is a sensitive indicator of the hydrological response to climate change. Variability in annual lake evaporation has been assumed to be controlled primarily by the incoming surface solar radiation. Here we report simulations with a numerical model of lake surface fluxes, with input data based on a high-emissions climate change scenario (Representative Concentration Pathway 8.5). In our simulations, the global annual lake evaporation increases by 16% by the end of the century, despite little change in incoming solar radiation at the surface. We attribute about half of this projected increase to two effects: periods of ice cover are shorter in a warmer climate and the ratio of sensible to latent heat flux decreases, thus channelling more energy into evaporation. At low latitudes, annual lake evaporation is further enhanced because the lake surface warms more slowly than the air, leading to more long-wave radiation energy available for evaporation. We suggest that an analogous change in the ratio of sensible to latent heat fluxes in the open ocean can help to explain some of the spread among climate models in terms of their sensitivity of precipitation to warming. We conclude that an accurate prediction of the energy balance at the Earth’s surface is crucial for evaluating the hydrological response to climate change.
Agriculture is the largest global consumer of water. Irrigated areas constitute 40 % of the total area used for agricultural production (FAO, 2014a) Information on their spatial distribution is highly relevant for regional water management and food security. Spatial information on irrigation is highly important for policy and decision makers, who are facing the transition towards more efficient sustainable agriculture. However, the mapping of irrigated areas still represents a challenge for land use classifications, and existing global data sets differ strongly in their results. The following study tests an existing irrigation map based on statistics and extends the irrigated area using ancillary data. The approach processes and analyzes multi-temporal normalized difference vegetation index (NDVI) SPOT-VGT data and agricultural suitability data – both at a spatial resolution of 30 arcsec – incrementally in a multiple decision tree. It covers the period from 1999 to 2012. The results globally show a 18 % larger irrigated area than existing approaches based on statistical data. The largest differences compared to the official national statistics are found in Asia and particularly in China and India. The additional areas are mainly identified within already known irrigated regions where irrigation is more dense than previously estimated. The validation with global and regional products shows the large divergence of existing data sets with respect to size and distribution of irrigated areas caused by spatial resolution, the considered time period and the input data and assumption made.
Caspian Sea level (CSL) has undergone substantial fluctuations during the past several hundred years. The causes over the entire historical period are uncertain, but we investigate here large changes seen in the past several decades. We use climate model-predicted precipitation (P), evaporation (E), and observed river runoff (R) to reconstruct long-term CSL changes for 1979–2015 and show that PER (P-E + R) flux predictions agree very well with observed CSL changes. The observed rapid CSL increase (about 12.74 cm/yr) and significant drop (~−6.72 cm/yr) during the periods 1979–1995 and 1996–2015 are well accounted for by integrated PER flux predictions of ~+12.38 and ~−6.79 cm/yr, respectively. We show that increased evaporation rates over the Caspian Sea play a dominant role in reversing the increasing trend in CSL during the past 37 years. The current long-term decline in CSL is expected to continue into the foreseeable future, under global warming scenarios.
Managing terminal lake elevation and salinity are emerging problems worldwide. We contribute to terminal lake management research by quantitatively assessing water and salt flow for Utah's Great Salt Lake. In 1959, Union Pacific Railroad constructed a rock-filled causeway across the Great Salt Lake, separating the lake into a north and south arm. Flow between the two arms was limited to two 4.6 meter wide rectangular culverts installed during construction, an 88 meter opening (referred to locally as a breach) installed in 1984, and the semi porous material of the causeway. A salinity gradient developed between the two arms of the lake over time because the south arm receives approximately 95% of the incoming streamflow entering Great Salt Lake. The north arm is often at, or near, salinity saturation, averaging 317 g/L since 1966, while the south is considerably less saline, averaging 142 g/L since 1966. Ecological and industrial uses of the lake are dependent on long-term salinity remaining within physiological and economic thresholds, although optimal salinity varies for the ecosystem and between diverse stakeholders. In 2013, Union Pacific Railroad closed causeway culverts amid structural safety concerns and proposed to replace them with a bridge, offering four different bridge designs. As of summer 2015, no bridge design has been decided upon. We investigated the effect that each of the proposed bridge designs would have on north and south arm Great Salt Lake elevation and salinity by updating and applying US Geological Survey's Great Salt Lake Fortran Model. Overall, we found that salinity is sensitive to bridge size and depth, with larger designs increasing salinity in the south arm and decreasing salinity in the north arm. This research illustrates that flow modifications within terminal lakes cannot be separated from lake salinity, ecology, management, and economic uses.
In recent years, there has been a developing trend of labelling some disasters as ‘climate change disasters’. In doing so, a discursive phenomenon can emerge that the authors have coined ‘climatization’ which is specified as framing a disastrous event or degraded environmental condition as caused by climate change, in order to reach an intended goal or to distract the discussion from the real problem which might have a different root course than caused by the climate change effects.
The implications of climatization are currently unclear – particularly to what extent climatizing a disaster might increase or decrease the vulnerability of a population at risk of disaster. The purpose of this paper is thus to open up the concept of climatization to investigation, and examine what affect such a discursive framing might have on public and political perception.
Climatization is here discussed in the context of Bangladesh – a country that is expected to be among the worst affected by climate change and a country in which some people claim the effects of climate change can already be seen. A qualitative field study which included key informant interviews, focus group discussions and a literature review was conducted in Bangladesh.
The study found recent examples of climatization related to Cyclone Aila (2009) and salt water intrusion in Bangladesh. In most cases these disasters were climatized in order to create a sense of urgency in order to push for an increase in financial aid to Bangladesh and to deflect responsibility for inaction that led up to the disaster. This study urges caution as there is a potential for climatization to be used as a means to cover up negligence or bad management and there is a risk that by climatizing a disaster key vulnerabilities may be overlooked.
Lake Urmia, one of the largest saltwater lakes on earth and a highly endangered ecosystem, is on the brink of a major environmental disaster similar to the catastrophic death of the Aral Sea. With a new composite of multi-spectral high resolution satellite observations, we show that the area of this Iranian lake has decreased by around 88% in the past decades, far more than previously reported (~ 25% to 50%). The lake's shoreline has been receding severely with no sign of recovery, which has been partly blamed on prolonged droughts. We use the lake basin's satellite-based gauge-adjusted climate record of the Standardized Precipitation Index data to demonstrate that the on-going shoreline retreat is not solely an artifact of prolonged droughts alone. Drastic changes to lake health are primarily consequences of aggressive regional water resources development plans, intensive agricultural activities, anthropogenic changes to the system, and upstream competition over water. This commentary is a call for action to both develop sustainable restoration ideas and to put new visions and strategies into practice before Lake Urmia falls victim to the Aral Sea syndrome.
The Bear River contributes more water to the eastern Great Basin than any other river
21 system. It is also the most significant source of water for the burgeoning Wasatch Front
22 metropolitan area in Northern Utah. Despite its importance for water resources for the region’s
23 agricultural, urban, and wildlife needs, our understanding of the variability of Bear River’s
24 stream flow derives entirely from the short instrumental record (1943-2010). Here we present a
25 1,200-year calibrated and verified tree-ring reconstruction of stream flow for the Bear River that
26 explains 67% of the variance of the instrumental record over the period from 1943-2010.
27 Furthermore, we developed this reconstruction from a species that is not typically used for
28 dendroclimatology, Utah juniper (Juniperus osteosperma). We identify highly significant
29 periodicity in our reconstruction at quasi-decadal (7-8 year), multi-decadal (30 year), and
centennial (>50 years) scales. The latter half of the 20th century was found to be the 2nd 30 wettest
(~40-year) period of the past 1,200 years, while the first half of the 20th century marked the 4th 31
32 driest period. The most severe period of reduced stream flow occurred during the Medieval
33 Warm Period (ca. mid-1200s CE) and persisted for ~70 years. Upper-level circulation anomalies
34 suggest that atmospheric teleconnections originating in the western tropical Pacific are
35 responsible for the delivery of precipitation to the Bear River watershed during the October-
36 December (OND) season of the previous year. The Bear River flow was compared to recent
37 reconstructions of the other tributaries to the Great Salt Lake (GSL) and the GSL level.
38 Implications for water management could be drawn from the observation that the latter half of
the 20th century was the 2nd 39 wettest in 1200 years, and that management for future water supply
40 should take into account the stream flow variability over the past millennium.
The trends in hydrological and climatic time series data of Urmia Lake basin in Iran were examined using the four different versions of the Mann-Kendall (MK) approach: (i) the original MK test; (ii) the MK test considering the effect of lag-1 autocorrelation; (iii) the MK test considering the effect of all autocorrelation or sample size; and (iv) the MK test considering the Hurst coefficient. Identification of hydrological and climatic data trends was carried out at monthly and annual time scales for 25 temperature, 35 precipitation and 35 streamflow gauging stations selected from the Urmia Lake basin. Mann-Kendall and Pearson tests were also applied to explore the relationships between temperature, precipitation and streamflow trends. The results show statistically significant upward and downward trends in the annual and monthly hydrological and climatic variables. The upward trends in temperature, unlike streamflow, are much more pronounced than the downward trends, but for precipitation the behaviour of trend is different on monthly and annual time scales. Furthermore, the trend results were affected by the different approaches. Specifically, the number of stations showing trends in hydrological and climatic variables decreased significantly (up to 50%) when the fourth test was considered instead of the first and the absolute value of the Z statistic for most of the time series was reduced. The results of correlations between streamflow and climatic variables showed that the streamflow in Urmia Lake basin is more sensitive to changes in temperature than those of precipitation. The observed decreases in streamflow and increases in temperature in the Urmia Lake basin in recent decades may thus have serious implications for water resources management under the warming climate with the expected population growth and increased freshwater consumption in this region.
We present a 576-year tree-ring-based reconstruction of streamflow for northern Utah's Weber River that exhibits considerable interannual and decadal-scale variability. While the 20th Century instrumental period includes several extreme individual dry years, it was the century with the fewest such years of the entire reconstruction. Extended droughts were more severe in duration, magnitude, and intensity prior to the instrumental record, including the most protracted drought of the record, which spanned 16 years from 1703 to 1718. Extreme wet years and periods are also a regular feature of the reconstruction. A strong early 17th Century pluvial exceeds the early 20th Century pluvial in magnitude, duration, and intensity, and dwarfs the 1980s wet period that caused significant flooding along the Wasatch Front. The long-term hydroclimatology of northern Utah is marked by considerable uncertainty; hence, our reconstruction provides water managers with a more complete record of water resource variability for assessment of the risk of droughts and floods for one of the largest and most rapidly growing population centers in the Intermountain West.
The drawdown trend of the water level in Urmia
Lake poses a serious problem for northwestern Iran which has
had negative impacts on agriculture and industry. This research
investigated likely causes of the predicament by estimating
trends in the time series of hydroclimatic variables of
the basin. Three non-parametric statistical tests, the Mann–
Kendall, Spearman rho, and Sen’s T, were applied to estimate
the trends in the annual and seasonal time series of temperature,
precipitation, and streamflow at 95 stations throughout
the basin. The Theil–Sen method was also used to estimate the
slopes of trend lines of annual time series. The results showed
a significant increasing trend of temperature throughout the
basin and an area-specific precipitation trend. The tests also
confirmed a general decreasing trend in the basin streamflow
that was more pronounced in the downstream stations. The
annual trend line slope was found to be from 0.02 to 0.14 °C/
year, −7.5 to 3.8 mm/year, and −0.01 to −0.4 m3/s/year for
temperature, precipitation, and streamflow, respectively. The
homogeneity of the monthly trends was also evaluated using
the Van Belle and Hughes tests as confirmation. Temporal
analyses of the trends for the temperature and streamflow of
the basin detected significant increasing trends beginning in
the mid-1980s and 1990s. The correlations between
streamflow and climate variables (temperature and precipitation)
were detected by Pearson’s test. The results showed that
the streamflow in Urmia Lake basin is more sensitive to
changes in temperature than precipitation. In general, the
decline in the lake water level can be related to both the
increase of temperature in the basin and an improvement in
over-exploitation of the water resources.
Highlights
► Evaporation from an Australian reservoir is analysed under a changing climate. ► Future climate predictions from 9 GCMs are used as driving forces. ► Evaporation will not be changing significantly in the next 50 years. ► Evaporation is expected to be 14.5% higher than current annual evaporation in 2080. ► The main agent behind this increase is higher air temperatures.
The Great Salt Lake is a closed basin lake in which level and volume fluctuate due to differences between inflows and outflows. The only outflow is evaporation, which depends directly on lake area and salinity, both of which depend on lake volume. The lake's level, volume, and area adjust to balance, on average, precipitation and streamflow inflows by evaporation. In this paper, we examine the sensitivity of lake volume changes to precipitation, streamflow, and evaporation and the interactions among these processes and lake area and salinity related to volume. A mass balance model is developed to generate representative realizations of future lake level from climate and streamflow inputs simulated using the k-nearest-neighbor method. Climate and salinity are used to estimate evaporation from the lake using a Penman model adjusted for the salinity-dependent saturation vapor pressure. Our results show that fluctuation in streamflow is the dominant factor in lake level fluctuations, but fluctuations in lake area that modulate evaporation and precipitation directly on the lake are also important. The results also quantify the sensitivity of lake level to changes in streamflow and air temperature inputs. They predict that a 25% decrease in streamflow would reduce lake level by about 66 cm (2.2 feet), while a +4°C air temperature increase would reduce lake level by about 34 cm (1.1 feet) on average. This sensitivity is important in evaluating the impacts of climate change or streamflow change due to increased consumptive water use on the level of the lake.
Over the last 40 years, Lake Chad, once the sixth largest lake in the world, has decreased by more than 90% in area. In this study, we use a hydrological model coupled with a lake/wetland algorithm to simulate the effects of lake bathymetry, human water use, and decadal climate variability on the lake's level, surface area, and water storage. In addition to the effects of persistent droughts and increasing irrigation withdrawals on the shrinking, we find that the lake's unique bathymetry—which allows its division into two smaller lakes—has made it more vulnerable to water loss. Unfortunately the lake's split is favored by the 1952–2006 climatology. Failure of the lake to remerge with renewed rainfall in the 1990s following the drought years of the 1970s and 1980s is a consequence of irrigation withdrawals. Under current climate and water use, a full recovery of the lake is unlikely without an inter-basin water transfer. Breaching the barrier separating the north and south lakes would reduce the amount of supplemental water needed for recovery.
Drawing upon a variety of existing maps, data and information, a new Global Lakes and Wetlands Database (GLWD) has been created. The combination of best available sources for lakes and wetlands on a global scale (1:1 to 1:3 million resolution), and the application of Geographic Information System (GIS) functionality enabled the generation of a database which focuses in three coordinated levels on (1) large lakes and reservoirs, (2) smaller water bodies, and (3) wetlands. Level 1 comprises the shoreline polygons of the 3067 largest lakes (surface area ≥50 km2) and 654 largest reservoirs (storage capacity ≥0.5 km3) worldwide, and offers extensive attribute data. Level 2 contains the shoreline polygons of approx. 250,000 smaller lakes, reservoirs and rivers (surface area ≥0.1 km2), excluding all water bodies of level 1. Finally, level 3 represents lakes, reservoirs, rivers, and different wetland types in the form of a global raster map at 30-second resolution, including all water bodies of levels 1 and 2.In a validation against documented data, GLWD proved to represent a comprehensive database of global lakes ≥1 km2 and to provide a good representation of the maximum global wetland extent. GLWD-1 and GLWD-2 establish two global polygon maps to which existing lake registers, compilations or remote sensing data can be linked in order to allow for further analyses in a GIS environment. GLWD-3 may serve as an estimate of wetland extents for global hydrology and climatology models, or to identify large-scale wetland distributions and important wetland complexes.
The Aral Sea in the Soviet Union, formerly the world's fourth largest lake in area, is disappearing. Between 1960 and 1987,
its level dropped nearly 13 meters, and its area decreased by 40 percent. Recession has resulted from reduced inflow caused
primarily by withdrawals of water for irrigation. Severe environmental problems have resulted. The sea could dry to a residual
brine lake. Local water use is being improved and schemes to save parts of the sea have been proposed. Nevertheless, preservation
of the Aral may require implementation of the controversial project to divert water from western Siberia into the Aral Sea
basin.
In transboundarywatersheds drainingwater-limited regions equitable
water sharing plays a key role in peaceable relations amongst nations.
In the simplest sense, a water sharing agreement (WSA)
involves determining: 1) the quantity of water naturally available,
2) what proportion of available water is allocated to each riparian, and
3) how global change will impact future water availability over the
term of the WSA—an Anthropocene Epoch consideration. Wine et al.
(2019) examines changes in the water balance of the Sea of Galilee
(SG) as a consequence of changing flows in the Upper Jordan River
(UJR), a transboundary watershed in which Lebanon, Israel, the
Kingdom of Jordan (KOJ) and the Palestinian Authority hold riparian
water rights.
Lake Urmia—a shallow endemic hypersaline lake in northwest Iran—has undergone a dramatic decline in its water level (WL), by about 8 m, since 1995. The primary cause of the WL decline in Lake Urmia has been debated in the scientific literature, regarding whether it has been predominantly driven by atmospheric climate change or by human activities in the watershed landscape. Using available climate, hydrological, and vegetation data for the period 1981–2015, this study analyzes and aims to explain the lake desiccation based on other observed hydro-climatic and vegetation changes in the Lake Urmia watershed and classical exploratory statistical methods. The analysis accounts for the relationships between atmospheric climate change (precipitation P, temperature T), and hydrological (soil moisture SM, and WL) and vegetation cover (VC; including agricultural crops and other vegetation) changes in the landscape. Results show that P, T, and SM changes cannot explain the sharp decline in lake WL since 2000. Instead, the agricultural increase of VC in the watershed correlates well with the lake WL change, indicating this human-driven VC and associated irrigation expansion as the dominant human driver of the Lake Urmia desiccation. Specifically, the greater transpiration from the expanded and increasingly irrigated agricultural crops implies increased total evapotranspiration and associated consumptive use of water (inherently related to the irrigation and water diversion and storage developments in the watershed). Thereby the runoff from the watershed into the lake has decreased, and the remaining smaller inflow to the lake has been insufficient for keeping up the previous lake WL, causing the observed WL drop to current conditions.
Uncertainty is a defining characteristic of hydrologic investigations, with increasing recognition of parameter, structural, measurement, and prediction uncertainty. Here we suggest that an additional form of uncertainty—(geo)political uncertainty—is locally important, but commonly neglected. We define geopolitical uncertainty in hydrology as indefiniteness of water balance processes, the relative magnitude of hydrologic fluxes, or causality as a consequence of complex international relations amongst riparians of a transboundary basin forced by internal economic, political, and nationalistic drivers (as well as interactions amongst these drivers) under a regime of non-stationary climate. We suggest that such (geo)political uncertainty has developed in the Jordan River basin as a consequence of intentionally ambiguous language in the Israel Jordan Peace Treaty, outstanding discussions regarding water allocations to the Palestinian Authority, and lobbying by the powerful agricultural sector. In the presence of economic motives requiring consumption of water these drivers promote securitization manifested as secrecy regarding water management and consumption by the upstream riparian, which given non-stationary climate opens a void of (geo)political uncertainty in which the relative importance of climate variability and change becomes indeterminate relative to changing water consumption, thereby perhaps allowing the upstream riparian to increase water consumption. The consequence of this (geo)political uncertainty for hydrologic studies is large water balance uncertainty, inability to reproduce water consumption studies due to data secrecy, and disagreement regarding the relative importance of pertinent drivers (i.e., climate versus consumption). Greater acknowledgement and awareness of (geo)political uncertainty’s impacts on hydrologic studies is needed, as are concerted efforts to reduce this uncertainty for the benefit of transparent water dialogue among riparians and knowledge-based management of common-pool resources.
The world's saline lakes are shrinking and human water diversions are a significant contributor. While there is increased interest in protecting the ecosystem services provided by these lakes, the cost of protecting water levels has not been estimated. To explore this question we consider the case of Great Salt Lake (Utah, USA) where human diversions from three rivers have caused the lake level to decline during the last century. Recent work has suggested the restoration of inflows is necessary to maintain a target elevation consistent with well-functioning ecosystems. We construct cost estimates of increasing water inflows using conservation opportunity cost curves for each river basin. We then compare the cost of uniform cutbacks to cap-and-trade systems which allow intra- and inter-basin trading. The cost of water to permanently implement uniform water right cutbacks to increase inflows by 20% above current levels is $37.4 million. Costs and cost-savings are sensitive to alternative allocation, inflow, and cost assumptions, and we estimate significant cost reductions from intra-basin water conservation markets (5–54% cost decrease) and inter-basin water conservation markets (22–57% cost decrease).
Many of the world's saline lakes are shrinking at alarming rates, reducing waterbird habitat and economic benefits while threatening human health. Saline lakes are long-term basin-wide integrators of climatic conditions that shrink and grow with natural climatic variation. In contrast, water withdrawals for human use exert a sustained reduction in lake inflows and levels. Quantifying the relative contributions of natural variability and human impacts to lake inflows is needed to preserve these lakes. With a credible water balance, causes of lake decline from water diversions or climate variability can be identified and the inflow needed to maintain lake health can be defined. Without a water balance, natural variability can be an excuse for inaction. Here we describe the decline of several of the world's large saline lakes and use a water balance for Great Salt Lake (USA) to demonstrate that consumptive water use rather than long-term climate change has greatly reduced its size. The inflow needed to maintain bird habitat, support lake-related industries and prevent dust storms that threaten human health and agriculture can be identified and provides the information to evaluate the difficult tradeoffs between direct benefits of consumptive water use and ecosystem services provided by saline lakes.
The natural flow regime of rivers has been strongly altered world-wide, resulting in ecosystem degradation and lakes drying up, especially in arid and semi-arid regions. Determining whether this is due mainly to climate change or to water withdrawal for direct human use (e.g. irrigation) is difficult, particularly for saline lake basins where hydrology data are scarce. In this study, we developed an approach for assessing climate and land use change impacts based on river flow records for headwater and lowland reaches of rivers, using the case of Lake Urmia basin, in north-westen Iran. Flow regimes at upstream and downstream stations were studied before and after major dam construction and irrigation projects. Data from 57 stations were used to establish five different time intervals representing 10 different land use development periods (scenarios) for upstream (not impacted) and downstream (impacted) systems. An existing river impact (RI) index was used to assess changes in three main characteristics of flow (magnitude, timing and, intra-annual variability). The results showed that irrigation was by far the main driving force for river flow regime changes in the lake basin. All stations close to the lake and on adjacent plains showed significantly higher impacts of land use change than headwaters. As headwaters are relatively unaffected by agriculture, the non-significant changes observed in headwater flow regimes indicate a minor effect of climate change on river flows in the region. The benefit of the method developed is clear interpretation of results based on river flow records, which is useful in communicating land use and climate change information to decision makers and lake restoration planners.
The response of hypersaline terminal lakes to negative water balance was investigated by studying brines evaporating to extreme salinities in sinkholes along the western coast of the Dead Sea and during on-site evaporation experiments of the Dead Sea brine. Density and temperature were determined in the field and all samples were analyzed for their major and a few minor solutes. The activity of H2O (aH2O) in the brines was calculated, and the degree of evaporation (DE) was established using Sr²⁺as a conservative solute. The relations between density and water activity were obtained by polynomial regression, and the relation between the lake's volume and level was established using Hall's (1996) hypsographic model for the Dead Sea basin. Relating the results to the modern, long-term relative humidity (RH) over the basin shows that (a) The lowermost attainable level of a terminal lake undergoing evaporation with no inflow is dictated by the median RH; this level represents equilibrium between the brine's aH2O and RH; (b) Small, saline water bodies with high surface to volume ratios (A/V), such as the hypersaline brines in the sinkholes, are very sensitive to short term changes in RH; in these, the brines' aH2O closely follows the seasonal changes; (c) the level decline of the Dead Sea due to evaporation under present climatic conditions and assuming no inflow to the lake may continue down to 516–537 m below mean sea level (bmsl), corresponding to a water activity range of 0.46–0.39 in its brine, in equilibrium with the overlying relative air humidity; this suggests that the lake level cannot drop more than ∼100 m from its present level; and (d) The maximum RH values that existed over the precursor lake of the Dead Sea (Lake Lisan) during geologically reconstructed minima levels can be similarly calculated.
The trends in hydrological and climatic time series data of Urmia Lake basin in Iran were examined
using the four different versions of the Mann-Kendall (MK) approach: (i) the original MK test; (ii) the MK
test considering the effect of lag-1 autocorrelation; (iii) the MK test considering the effect of all
autocorrelation or sample size; and (iv) the MK test considering the Hurst coefficient. Identification of
hydrological and climatic data trends was carried out at monthly and annual time scales for 25
temperature, 35 precipitation and 35 streamflow gauging stations selected from the Urmia Lake
basin. Mann-Kendall and Pearson tests were also applied to explore the relationships between temperature,
precipitation and streamflow trends. The results show statistically significant upward and
downward trends in the annual and monthly hydrological and climatic variables. The upward trends in
temperature, unlike streamflow, are much more pronounced than the downward trends, but for
precipitation the behaviour of trend is different on monthly and annual time scales. Furthermore, the
trend results were affected by the different approaches. Specifically, the number of stations showing
trends in hydrological and climatic variables decreased significantly (up to 50%) when the fourth test
was considered instead of the first and the absolute value of the Z statistic for most of the time series
was reduced. The results of correlations between streamflow and climatic variables showed that the
streamflow in Urmia Lake basin is more sensitive to changes in temperature than those of precipitation.
The observed decreases in streamflow and increases in temperature in the Urmia Lake basin in recent
decades may thus have serious implications for water resources management under the warming
climate with the expected population growth and increased freshwater consumption in this region.
Lake level and volume are sensitive to climate change, and their changes can affect the sustainable utilization of regional water resources. Satellite radar/laser altimetry has effectively been used for monitoring water-level changes in recent years. In this study, satellite altimetry data and optical images were used to assess the changes in water level, area, and volume of Hulun Lake in north-eastern China. We derived a time series of lake levels for nearly two decades (1992 to 2010) from the altimetry data of two satellite sensors (Topex/Poseidon and Envisat RA-2); additionally, lake surface extent was extracted from Landsat TM/ETM+ images during the same period. The results indicate that the water level, area, and volume of Hulun Lake decreased over the past two decades. The water level shows a significant decrease (-0.36 m/year) of a total of -5.21 m from 1992 to 2010, specifically including a slight decrease (-0.4 m) during 1992 to 1999 and a sudden drop (-4.81 m) during 2000 to 2010. There has also been a consistent and significant reduction in lake area (-355.35 km2) and volume (-12.92 km3). An integrated examination on changes in temperature, evaporation, precipitation, and runoff during 1992 to 2010 shows that the main changes in the Hulun Lake area are correlated with increasing temperature (0.47°C/year) and evaporation (13.61 mm/year), as well as decreasing precipitation (-6.58 mm/year) and runoff (-1.04×108 m3/year). Thus, we infer that climate warming is likely the main cause of the changes in water level, area, and volume of Hulun Lake. In addition, anthropogenic factors accelerate the degradation of the Hulun Lake wetland to some extent. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).
Although extremely important to migrating waterfowl and shorebirds, and highly threatened globally, most saline lakes are poorly monitored. Lake Abert in the western Great Basin, USA, is an example of this neglect. Designated a critical habitat under the Western Hemisphere Shorebird Reserve Network, the lake is at near record historic low levels and ultra-high salinities that have resulted in ecosystem collapse. Determination of the direct human effects and broader climate controls on Lake Abert illustrates the broader problem of saline lake desiccation and suggests future solutions for restoration of key habitat values. A 65-year time series of lake area was constructed from Landsat images and transformed to lake volume and salinity. "Natural" (without upstream withdrawals) conditions were calculated from climate and stream flow data, and compared to measured volume and salinity. Under natural conditions the lake would have higher volume and lower salinities because annual water withdrawals account for one-third of mean lake volume. Without withdrawals, the lake would have maintained annual mean salinities mostly within the optimal range of brine shrimp and alkali fly growth. Even during the last two years of major drought, the lake would have maintained salinities well below measured values. Change in climate alone would not produce the recent low lake volumes and high salinities that have destroyed the brine shrimp and alkali fly populations and depleted shorebird use at Lake Abert. Large scale withdrawal of water for direct human use has drastically increased the imbalance between natural runoff and evaporation during periods of drought in saline lakes worldwide but could be offset by establishing an "environmental water budget" to lay a foundation for the conservation of saline lake habitats under continued threats from development and climate change.
The relationships between the evaporation from a medium size (168.7 km2) Lake Kinneret (Northern Israel), and its governing synoptic factors are well demonstrated during the summer of 2010. During July-August the daily temperature of the air and water surface were ~2-4oC higher, the daily wind over the lake was ~80% weaker, and the evaporation from the lake was ~5% lower than the long-term July-August mean. In this study, we explore the impact of the regional and local synoptic-scale atmospheric conditions on the evaporation from the lake during exceptionally hot days in the mid-summer months (July – August). The factors that were found to be correlated with the lake evaporation are the temperatures at 850 hPa (negative) and 500 hPa (positive), the sea level pressure difference between Northern Egypt and Armenia (positive), and the height of the marine inversion (positive). Synoptic analysis indicates that two conditions are responsible for the reduction of the Mediterranean Sea Breeze (MSB) during exceptionally hot days, and consequently to the reduction of evaporation from the lake. First, the weakening of the permanent synoptic Etesian winds, which otherwise supports the inland penetration of the MSB; and second, the descent of the marine inversion to a height below the topographic ridge of the Galilee Mountains upwind of the study area, which blocks the Marine Sea Breeze from reaching Lake Kinneret.
[1] We created six new tree-ring chronologies in northern Utah, which were used with preexisting chronologies from Utah and western Wyoming to reconstruct mean annual flow for the Logan River, the largest tributary of the regionally important Bear River. Two reconstruction models were developed, a “Local” model that incorporated two Rocky Mountain juniper chronologies located within the basin, and a “Regional” model that also included limber pine and pinyon pine chronologies from a larger area. The Local model explained 48.2% of the variability in the instrumental record and the juniper chronologies better captured streamflow variability than Douglas-fir collected within the Logan basin. Incorporating chronologies from the northern and southern margins of the transition zone of the western precipitation dipole increased the skill of the Regional model (r2 = 0.581). We suggest the increased Regional model skill indicates that both nodes of the western precipitation dipole influence northern Utah climate. The importance of Rocky Mountain juniper in both reconstructions of streamflow for this region suggests that future work should target these trees where more traditionally desirable species are not present. The reconstructions provide the first extended record of streamflow in northern Utah. Preinstrumental streamflows (1605–1921) exhibited considerable variability when compared to the instrumental period (1922–2005). Our findings confirm that the inherent uncertainty in contemporary water management and planning in the region is due to hydroclimatic variability that has persisted for at least the last four centuries.
The possible effects of trace-gas induced climatic changes on Pyramid and Yellowstone Lakes are assessed using a model of lake temperature. The model is driven by years of hourly meteorological data obtained directly from the output of double-CO2 experiments (2 × CO2) conducted with a regional climate model nested in a general circulation model. The regional atmospheric model is the climate version of the National Center for Atmospheric Research/Pennsylvania State University mesoscale model, MM4.Average annual surface temperature of Pyramid Lake for the 2 × CO2 climate is 15.5 ± 5.4°C (±1 σ), 2.8°C higher than the control. Annual overturn of the lake ceases as a result of these higher temperatures for the 2 × CO2 climate. Evaporation increases from 1400 mm yr−1 in the control to 1595 mm yr−1 in the 2 × CO2 simulation, but net water supplied to the Pyramid Lake basin increases from −6 mm yr−1 in the control to +27 mm yr−1 in the 2 × CO2 simulation due to increased precipitation.For the open water periods, the average annual surface temperature of Yellowstone Lake is 13.2 ± 5.1°C for the 2 × CO2 climate, a temperature 1.6°C higher than the control. The annual duration of ice cover on the lake is 152 days in the 2 × CO2 simulation, a reduction of 44 days relative to the control. Warming of the lake for the 2 × CO2 climate is mostly confined to the near-surface. Simulated spring overturn for the 2 × CO2 climate occurs earlier in the year and fall overturn later than in the control. Evaporation increases from 544 mm yr−1 to 600 mm yr−1 in the 2 × CO2 simulation, but net water supplied to the Yellowstone Lake basin increases from +373 mm yr−1 in the control to +619 mm yr−1 due to increased precipitation. The effects of these climatic changes suggest possible deterioration of water quality and productivity in Pyramid Lake and possible enhancement of productivity in Yellowstone Lake.
s u m m a r y Identifying and quantifying future climate effects on water resources has major economic and societal implications, rendering such studies extremely important for water planners. Here we integrate output from one high resolution global (Japan Meteorological Agency) and three regional (ECHAM-RegCM, Hadley-MM5, ECHAM-MM5) climate models into three hydrological tools (1. annual incoming water vol-umes; 2. evaporation from the lake; and 3. lake salinity) to provide first approximations of climate change impacts on water quantity and quality in Lake Kinneret (also known as Sea of Galilee), the major fresh-water resource in Israel. Meteorological data extracted from the climate models were used as input data into the models. Results were calculated for the historical 1979–2009 and the future 2015–2060 periods. The modeled historical period was verified against observed data, first by each model alone, and then by the combined model structure. Predicted results varied between the climate models. The ECHAM-RegCM predicted decreased precipitation in an average rate of 450 ppm Cl in 2060), while the trends of salinity according to other models were mild.
Variability and unpredictability are characteristics of the aquatic ecosystems, hydrological patterns and climate of the largely dryland region that encompasses the Basin and Range, American Southwest and western Mexico. Neither hydrological nor climatological models for the region are suciently developed to describe the magnitude or direction of change in response to increased carbon dioxide; thus, an attempt to predict speci®c responses of aquatic ecosystems is premature. Instead, we focus on the sensitivity of rivers, streams, springs, wetlands, reservoirs, and lakes of the region to potential changes in climate, especially those inducing a change in hydrological patterns such as amount, timing and predictability of stream ¯ow. The major sensitivities of aquatic ecosystems are their permanence and even existence in the face of potential reduced net basin supply of water, stability of geomorphological structure and riparian ecotones with alterations in disturbance regimes, and water quality changes resulting from a modi®ed water balance. In all of these respects, aquatic ecosystems of the region are also sensitive to the extensive modi®cations imposed by human use of water resources, which underscores the diculty of separating this type of anthropogenic change from climate change. We advocate a focus in future research on reconstruction and analysis of past climates and associated ecosystem characteristics, long-term studies to discriminate directional change vs. year to year variability (including evidence of aquatic ecosystem responses or sensi-tivity to extremes), and studies of ecosystems aected by human activity. # 1997 by John Wiley & Sons, Ltd.
The Aral Sea is a huge terminal lake located among the deserts of Central Asia. Over the past 10 millennia, it has repeatedly filled and dried, owing both to natural and human forces. The most recent des-iccation started in the early 1960s and owes overwhelmingly to the expansion of irrigation that has drained its two tributary rivers. Lake level has fallen 23 m, area shrunk 74%, volume decreased 90%, and salinity grew from 10 to more than 100g/l, causing negative ecolog-ical changes, including decimation of native fish species, initiation of dust/salt storms, degradation of deltaic biotic communities, and climate change around the former shoreline. The population resid-ing around the lake has also been negatively impacted. There is little hope in the foreseeable future to fully restore the Aral Sea, but mea-sures to preserve/rehabilitate parts of the water body and the deltas are feasible.
Salt lakes have a variety of important uses and values, including especially both economic and scientific ones. These uses and values have been and are increasingly subject to degradation from a variety of impacts: diversion of inflows, pollution, agricultural practices, and introduction of exotic species are among the more important. Recognition of these impacts upon salt lakes has led to some international and national measures for their conservation, but considerably more effort in this direction is needed. Against this background, Mono Lake, California, USA, and the Aral Sea, central Asia, are discussed as two localities which bring into sharp focus the various matters discussed in the paper. Finally, attention is drawn to the need to conserve the Akrotiri Salt Lake, Cyprus.
One of the more important questions in hydrology is: if the climate warms in the future, will there be an intensification of the water cycle and, if so, the nature of that intensification? There is considerable interest in this question because an intensification of the water cycle may lead to changes in water-resource availability, an increase in the frequency and intensity of tropical storms, floods, and droughts, and an amplification of warming through the water vapor feedback. Empirical evidence for ongoing intensification of the water cycle would provide additional support for the theoretical framework that links intensification with warming. This paper briefly reviews the current state of science regarding historical trends in hydrologic variables, including precipitation, runoff, tropospheric water vapor, soil moisture, glacier mass balance, evaporation, evapotranspiration, and growing season length. Data are often incomplete in spatial and temporal domains and regional analyses are variable and sometimes contradictory; however, the weight of evidence indicates an ongoing intensification of the water cycle. In contrast to these trends, the empirical evidence to date does not consistently support an increase in the frequency or intensity of tropical storms and floods.
There is no black hole swallowing water in the Hula Valley
- M L Wine
Wine, M.L. There is no black hole swallowing water in the Hula Valley. Land Use Policy 2019, 84, 363-364.
[CrossRef]
Climaticization of environmental degradation-An Anthropocene epoch response to failure of governance
- M L Wine
Wine, M.L. Letter to editor re Tal (2019): Climaticization of environmental degradation-An Anthropocene
epoch response to failure of governance. Sci. Total Environ. 2019. [CrossRef]
Agriculture, diversions, and drought shrinking Galilee Sea
- M L Wine
- A Rimmer
- J B Laronne
Wine, M.L.; Rimmer, A.; Laronne, J.B. Agriculture, diversions, and drought shrinking Galilee Sea. Sci. Total
Environ. 2019, 651, 70-83. [CrossRef] [PubMed]