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Stationarity Is Dead: Whither Water Management?
Abstract
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.
... One possibility, as I suggest elsewhere [51], is to increase the national role in water law and policy in ways that promote water sustainability and the transferability of either water-or the economies that rely on them-as the location of water supply shifts. Of course, given the high degree of variability in both physical and socio-economic conditions that affect or depend on water resources, broad-based national (in the United States, federal) policies require sufficient flexibility to address those differences, as well as unpredictably changing conditions [51,59]. ...
... Moreover, historically the U.S. federal government has been extremely reluctant to intrude directly on issues of individual state water law and management, as well as related issues of land use planning and regulation [51]. Ironically, however, the federal government ends up impinging on state water law indirectly through water subsidies, drought relief and other policies that distort the incentives inherent in state water law [59,60]. If federal drought relief and other policies change the economic dynamics of state water law anyway, it would be better to do so through direct, integrated approaches designed to promote more sustainable water uses and practices that help reduce society's vulnerability to drought. ...
Researchers and responsible officials have made considerable progress in recent years in efforts to anticipate, plan for, and respond to drought. Some of those efforts are beginning to shift from purely reactive, relief-oriented measures to programs designed to prevent or to mitigate drought impacts. Considerably less attention has been given to laws that may affect practices and policies that either increase or decrease drought vulnerability. Water law regimes, drought response and relief legislation, and laws governing broader but related issues of economic policy—especially agricultural policy—should be evaluated more comprehensively to enhance incentives for more “water sustainable” practices in agriculture and other sectors of the economy. Those changes will be increasingly important if current climate change models are correct in their prediction that many parts of the world can expect more frequent and more severe conditions of meteorological drought in the ensuing decades.
... The impact of climate change is becoming increasingly evident, as reflected in the rising frequency and intensity of extreme rainfall events [1][2][3][4]. These phenomena present unprecedented challenges to existing dam infrastructures whose original desgins were based on historical hydraulic data. ...
... Nonetheless, since the CPKW configuration is more complex than conventional PKWs, additional parameters have been included, such as W i,u -inlet key width upstream, W i,d -inlet key width downstream, W o,u -outlet key width upstream, W o,d -outlet key width downstream, SW i -trapezoidal side-wall length, and SW o -rectangular side-wall length. [2] h p = parapet wall height; [3] exp = experimental model; [4] num = numerical model. Bold numbers indicate parameters that are kept constant. ...
Climate-change-induced increases in extreme rainfall events necessitate the enhancement of discharge capacity in aging dam infrastructures. Piano Key Weirs (PKWs), with their compact footprint and efficient discharge performance, present a promising option for improving the discharge efficiency of existing spillways. This study introduces an innovative composite Piano Key Weir (CPKW), which integrates both rectangular and trapezoidal layouts. Numerical simulations were performed to systematically compare the flow field and discharge performance between conventional trapezoidal PKW and composite configurations. Results show that the composite structure significantly improves the discharge capacity of the reference trapezoidal model by up to 16%. This enhancement is primarily attributed to the extended crest length and reduced local submergence, resulting in a more efficient discharge distribution. For the specific composite configurations studied, the optimal key width ratio that effectively balances the inflow efficiency and the adverse effects of nappe interference is found to range between 0.89 and 1.01. Additionally, a relative upstream head of 0.2–0.3 is identified as a critical threshold, beyond which the intense local submergence starts to affect the downstream trapezoidal side-wall section, limiting the contribution of the entire side wall to the total discharge and resulting in decreased overall efficiency.
... Climate change has forced a rethink of contemporary river-management practices, which were largely built on the presumption of hydroclimatic stationarity 1,2 . The magnitude, frequency and timing of floods and droughts have departed from their historical averages across the globe in recent decades [3][4][5] . ...
... Great floods (those exceeding the present 100-year recurrence levels) are expected to recur as often as every two to five years in numerous regions globally 6,7 . Non-stationarity in river flow regimes puts pressure on aging infrastructure and management practices that were designed based on the historical range of variability 1 . Moreover, such alterations to flow regimes can exacerbate the impacts of existing human modifications on river environments 8 . ...
Floodplain river ecosystems have been extensively artificially constrained globally. As climate change heightens flood risks, the command-and-control approach to river flood management is beginning to make way for a paradigm shift towards ‘living with water’. The ecological co-benefits of this shift, where rivers are given the space they need to migrate on the landscape, have so far been undervalued. Here we synthesize the ecological benefits
of allowing rivers more room to move. We emphasize how the physical and ecological processes of unconfined river channels interact to provide the foundations for ecosystem resilience through spatiotemporal variability in multiple dimensions, including hydrologic and meta-ecosystem connectivity. More informed and sustainable decision-making that involves trade-offs between river ecology and engineering will be aided
by elucidating these connections. Giving rivers more room to move can represent a mutually beneficial solution for both the freshwater biodiversity crisis and flood hazard management as climate-driven extremes escalate.
... These interpretations assume that ecological communities exist within an equilibrium where resilient communities can return to and maintain a stable ecosystem state following disturbance, also known as ecological stationarity (Tilman 1996). Climate change threatens the idea of ecological stationarity because disturbances work synergistically with changing climatic conditions to push ecological communities outside their historical range of variation (Milly et al. 2008). Species additions or replacements in transforming ecosystems can drastically alter existing interactions and patterns, leading to new ecosystem states and potentially altering overall ecosystem function (Pecl et al. 2017). ...
Context
Consistent with the diversity-stability hypothesis, high wildlife diversity has been associated with increased resilience and stability of ecosystem services and functions. Nevertheless, ecological non-stationarity associated with climate change challenges the concept of stability. Furthermore, ambiguity surrounding appropriate diversity metrics to use has hindered the ability of natural resource managers to leverage the potential benefits of biodiversity conservation.
Objectives and methods
We aimed to infer how diversity and compositional stability might be affected by multiple climate and disturbance stressors, including management activity.
Methods
We used a spatially explicit landscape succession model to predict spatiotemporal patterns of beta diversity for terrestrial vertebrates representing three trophic groups (herbivores, insectivores, and predators) over an 80-year time span.
Results
Trends in diversity were driven by species gains at higher elevations and species losses at lower elevations, however, species reorganization was modified by both mean species turnover (i.e. replacement of species across space) as well as management intensity. Higher species turnover was associated with greater among-site compositional stability and decreased local compositional change attributed to species losses for all trophic groups. Increasing management intensity further increased beta diversity across all elevations whereas decreasing management intensity led to spatial homogenization of herbivores and insectivores at low elevations. High management intensity also weakened naturally occurring diversity-stability relationships at larger spatial scales.
Conclusions
Increasing management intensity may be beneficial at lower elevations where projections anticipate species losses and homogenization. Additionally, conserving areas of high diversity will likely be important for promoting future compositional stability for trophic groups that support key ecological processes.
... Climate change and human activities have led to the disruption of the stationarity in hydrological time series (Milly et al. 2008). Due to the nonstationary statistical characteristics of the multivariate variables for extreme rainfall events in a changing environment, using a stationary assumption in hydrological risk assessment or planning became inaccurate (Chen et al. 2024;Cheng et al. 2023;Wen et al. 2019). ...
The risk of extreme rainfall events has increased due to climate change, necessitating the risk assessment of extreme rainfall events under a nonstationary framework. Since short‐duration extreme rainfall events are more sensitive to environmental changes, and the current research on the risk of continuous short‐duration extreme rainfall events is insufficient, this study presents a methodological framework for assessing the risk of short‐duration rainfall extremes using a nonstationary model across the Huaihe River Basin in China from 1963 to 2015. The methodology includes the following components: (1) A quantile‐based approach was used to identify the short‐duration extreme rainfall events. (2) The risk of short‐duration extreme rainfall events caused by climate change was calculated using nonstationary bivariate models and compared with those from stationary models. (3) The design values corresponding to the most‐likely design event at different average annual reliability (AAR) were calculated based on copula models. The results illustrated that the intensity of rainfall duration and total rainfall of short‐duration extreme rainfall events in most stations increased significantly after 2000. The width of the 90% confidence interval for the design values estimated based on AAR increased under both nonstationary marginal distributions and nonstationary copula models, indicating that the calculation of the design values will be affected in both scenarios. Therefore, it is necessary to use nonstationary bivariate models to assess the risk of short‐duration extreme rainfall events under climate change. Overall, this study provides a systematic framework for conducting nonstationary risk assessments of short‐duration extreme rainfall events.
... Conversely, the autumnal window signifies the end of the growing season and the onset of winter, also involving quick transitions in ecosystem dynamics (Creed, Hwang, et al., 2015;Creed, McKnight, et al., 2015). The shift from stationary (oscillations) to non-stationary (trends) in climatic conditions (Milly et al., 2008) may change the patterns of hydrologic episodes and amplify alterations in hydrologically driven terrestrial export of biogeochemical constituents (Li et al., 2024;van Vliet et al., 2023). These patterns are already being affected by acidification and subsequent recovery in these forests (Gilliam et al., 2019). ...
Northern temperate forests are experiencing changes from climate and acidification recovery that influence catchment nitrate‐nitrogen (N) flushing behavior. N flushing behavior is characterized by metrics such as: (a) N flushing time—the exponential decrease in stream N concentration during the peak snowmelt episode; and (b) N concentration (C) and discharge (Q) hysteresis metrics—flushing index (FI) and hysteresis index (HI)—representing the slope, direction, and amplitude of the C‐Q loop. We hypothesized that climate‐driven hydrologic intensification results in longer N flushing times, lower FI (less flushing to more diluting), and lower HI (less proximal to more distal N sources). We tested this hypothesis using four decades of data from two headwater catchments. Hydrologic intensification was estimated by changes in the ratio of potential evapotranspiration to precipitation and the ratio of actual evapotranspiration to precipitation. From 1982 to 2005, a period characterized by hydrologic intensification and a decline in atmospheric acidic deposition, we observed a decrease in C and Q. This led to stable C‐Q patterns that reflected the flushing (positive FI) of proximal N sources (positive HI). However, from 2006 to 2019, a period of hydrologic de‐intensification coupled with an ongoing decline in atmospheric acidic deposition was associated with a continued decrease in C but an increase in Q, leading to unstable C‐Q patterns that reflected a shift from proximal (positive HI) toward distal N sources (negative HI). C‐Q instability was less variable in the catchment with a large wetland, indicating the potential of wetlands to buffer against changing climate conditions.
Hydrological processes, as part of a natural system, are highly complex and chaotic. By analyzing long time series of streamflow data from ~ 4800 hydrologic stations, it is interesting to find out that probability density functions in second order difference (SOD) of the streamflow data are fat-tailed and bell-shaped curves, and their cumulative distribution functions (CDFs) follow an S-shaped curve (S-curve). We found that t-distribution is a good approximation for S-curve, which uses the degree of freedom (DF) to control the tail thickness. We also found that DF of more than 80% of stations are gathered in the range between 5 and 8. Analysis of the S-curves in seven large river basins indicated that the S-curves can vary with time and space, which is regarded as a good indicator for identifying natural and anthropogenic changes. This study provides a symmetrical, identical and concise probability distribution to describe global streamflow under changing environment.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-025-98191-w.
Our water resources have changed over the last century through a combination of water management evolution and climate change. Understanding and decomposing the drivers of discharge changes is essential to preparing and planning adaptive strategies. To separate the response of catchment dynamics between climate change‐related and other factors in discharge observations, we propose a methodology to compare discharge observations to discharge from a physically based model. The novelty lies in the fact that, to keep the comparison pertinent despite systematic biases in physically based model outputs, we compare both systems using a common framework of interpretation, a parsimonious model, which allows us to isolate trends in catchment dynamics from trends due to average changes in annual climate variables. The modeled system stands as the reference to reproduce changes only due to evolving climate dynamics. Comparing it to the interpretation framework applied to the observation system highlights the effect of the non‐modeled factors on catchment dynamics and discharge, such as human intervention in rivers and water uptakes. We show that over Europe, especially in the South, the dominant explanations for discharge trends are non‐climatic factors. Still, in some catchments of Northern Europe, climate change seems to be the dominating driver of change. We hypothesize that the dominating non‐climatic factors are irrigation development, groundwater pumping and other human water usage. These results show the importance of including non‐climatic factors in physically based models to understand the main drivers of discharge better and accurately project future changes.
Climate records have been broken with alarming regularity in recent years, but the events of 2023–2024 were exceptional even when accounting for recent climatic trends. Here we quantify these events across multiple variables and show how excess energy accumulation in the Earth system drove the exceptional conditions. Key factors were the positive decadal trend in Earth’s Energy Imbalance (EEI), persistent La Niña conditions beginning in 2020, and the switch to El Niño in 2023. Between 2022 and 2023, the heating from EEI was over 75% larger than during the onset of similar recent El Niño events. We show further how regional processes shaped distinct patterns of record-breaking sea surface temperatures in individual ocean basins. If the recent trend in EEI is maintained, we argue that natural fluctuations such as ENSO cycles will increasingly lead to amplified, record-breaking impacts, with 2023–2024 serving as a glimpse of future climate extremes.
A Balaton vízháztartása az éghajlatváltozás miatt jelentős átalakuláson megy keresztül. Az átlagosan pozitív éves természetes vízkészletváltozás az előrejelzések többsége szerint csökkenni fog. Ezért éghajlati modelleredményekre támaszkodó hidrológiai és vízszintszabályozási modellekkel vizsgáltuk a tó vízszintjének várható változásait az optimista RCP4.5 és a realista RCP8.5 IPCC forgatókönyvekre. Az optimista éghajlati forgatókönyvben a tó jelenlegi alakja egészen a század végéig fennmarad, bár a vízállás – vízpótlás hiányában – átmenetileg többször nagyon alacsony tartományokba süllyed. A csak leeresztésre támaszkodó vízszintszabályozás ezeket a kilengéseket nem tudja megakadályozni, ezért a tóhasználat ma szokásos módjait 2040 után már valószínűleg csak időszakos vízpótlással lehet fenntartani. A realista forgatókönyvben a század utolsó harmadában a vízmérleg drámai romlása miatt a tó tartósan lefolyástalanná válik és jelenlegi kiterjedése is csak jelentős, a század vége felé már tartósan üzemelő vízpótlással tartható fenn. Az éghajlatváltozás és a kezelési módjának szánt tartósan magas vízállás is kedvezőtlen vízminőségi és ökológiai következményekkel jár. A vízpótlás lehetőségének megteremtésével lazítható lenne a jelenleg tározásra optimalizált vízszintszabályozási rend és ezzel enyhíthetők lennének a negatív ökológiai hatások. Ugyanakkor mivel a vízszintingadozások a jövőben minden előrejelzés szerint még egy fenntartható módon megtervezett vízpótlás mellett is elkerülhetetlenek lesznek, ezért haladéktalanul meg kell kezdeni az infrastruktúra és a vízhasználók felkészítését a változó vízszintekre.
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.
This study investigates the response of a global model of the climate to the quadrupling of the CO2 concentration in the atmosphere. The model consists of (1) a general circulation model of the atmosphere, (2) a heat and water balance model of the continents, and (3) a simple mixed layer model of the oceans. It has a global computational domain and realistic geography. For the computation of radiative transfer, the seasonal variation of insolation is imposed at the top of the model atmosphere, and the fixed distribution of cloud cover is prescribed as a function of latitude and of height. It is found that with some exceptions, the model succeeds in reproducing the large-scale characteristics of seasonal and geographical variation of the observed atmospheric temperature. The climatic effect of a CO2 increase is determined by comparing statistical equilibrium states of the model atmosphere with a normal concentration and with a 4 times the normal concentration of CO2 in the air. It is found that the warming of the model atmosphere resulting from CO2 increase has significant seasonal and latitudinal variation. Because of the absence of an albedo feedback mechanism, the warming over the Antarctic continent is somewhat less than the warming in high latitudes of the northern hemisphere. Over the Arctic Ocean and its surroundings, the warming is much larger in winter than summer, thereby reducing the amplitude of seasonal temperature variation. It is concluded that this seasonal asymmetry in the warming results from the reduction in the coverage and thickness of the sea ice. The warming of the model atmosphere results in an enrichment of the moisture content in the air and an increase in the poleward moisture transport. The additional moisture is picked up from the tropical ocean and is brought to high latitudes where both precipitation and runoff increase throughout the year. Further, the time of rapid snowmelt and maximum runoff becomes earlier.
The space‐time tradeoff of hydrologic data collection (the ability to substitute spatial coverage for temporal extension of records or vice versa) is controlled jointly by the statistical properties of the phenomena that are being measured and by the model that is used to meld the information sources. The control exerted on the space‐time tradeoff by the model and its accompanying errors has seldom been studied explicitly. The technique, known as Network Analyses for Regional Information (NARI), permits such a study of the regional regression model that is used to relate streamflow parameters to the physical and climatic characteristics of the drainage basin.
The NARI technique shows that model improvement is a viable and sometimes necessary means of improving regional data collection systems. Model improvement provides an immediate increase in the accuracy of regional parameter estimation and also increases the information potential of future data collection. Model improvement, which can only be measured in a statistical sense, cannot be quantitatively estimated prior to its achievement; thus an attempt to upgrade a particular model entails a certain degree of risk on the part of the hydrologist.
A condensed version of the Valencia-Schaake disaggregation model is developed which describes the distribution of monthly streamflow sequences using a set of coupled univariate regression models rather than a multivariate time series formulation. The condensed model has fewer parameters and is convenient for generating flow sequences which incorporate the intrinsic variability of streamflows and the uncertainty in the parameters of the annual and monthly streamflow models. The impact of parameter uncertainty on derived relationships between reservoir capacity and reservoir performance statistics is illustrated using required reservoir capacity (calculated with the sequent peak algorithm), system reliability, and the average total shortfall. Modeled sequences describe flows in the Rappahannock River in Virginia and the Boise River in Idaho. For high-reliability systems the results show that streamflow generation procedures which ignore model parameter uncertainty can grossly underestimate reservoir system failure rates and the severity of likely shortages, even if based on a 50-year record.
Alluvial records of paleofloods show that natural floods resulting from excessive rainfall, snowmelt, or from combined rainfall and snowmelt are highly sensitive to even modest changes of climate equivalent or smaller than changes expected from potential future global warming in the 21st century. The high sensitivity results from effects of hemispheric or global-scale changes in circulation patterns of the ocean and atmosphere to influence the pathways and locations of air masses and storm tracks. Holocene paleoflood chronologies from the Upper Mississippi Valley in the Midwest United States and from the Colorado River drainage of the Southwest United States show that recurrence frequencies of large floods have been subject to abrupt changes over time. These flood chronologies and flood chronologies observed for other middle-latitude regions suggest that recurrence frequencies of large floods are increased when there is an increase in the number of waves and their amplitudes in the middle and upper tropospheric circum-polar westerly circulation. However, some middle-latitude regions on the western margins of continents experience increased frequencies of flooding during strong onshore zonal westerly circulation. Flood chronologies from several regions suggest that times of rapid climate change have a tendency to be associated with more frequent occurrences of large and extreme floods. The unusual high frequencies of large floods that have been observed in many regions since the early 1950s are often attributed to land use change, but the rapid climate forcing from the effects of increased atmospheric greenhouse gases may also be a contributing factor. Paleoflood records provide information that is useful for better interpretation and calibration of modern short-term instrumental records, and they provide unique event-scale information that is useful for calibrating and testing geophysical models of past and anticipated future climate conditions.