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Relationship between reservoir performance and required reservoir storage calculated using the (a and c) sequent peak algorithm; (b and d) minimum 2-year precipitation, black dots represent select required storages and minimum 2-year precipitation values from the distribution of all synthetically generated realizations (obtained using Method 1 and Method 2)
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There are significant computational requirements for assessing climate change impacts on water resource system reliability andvulnerability, particularly when analyzing a wide range of plausible scenarios. These requirements often deter analysts from exhaustivelyidentifying climate hazards. This technical note investigates two approaches for genera...
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... is a close relationship between the SPA and performance metrics. This is because the selected simu- lations, based on the quantiles of the SPA metric distribution, will also represent similar quantiles in the distribution of performance metrics under natural climate variability (as represented by the 3,880 stochastic simulations) if the fits in Figs. 2(a and c) are very precise. As seen in Figs. 2(a and c), the relationship between res- ervoir performance and the SPA metric is clearly linear with some noise (Pearson's r value of −0.71 and 0.85 for reliability and vul- nerability, respectively). The strong fit suggests that the SPA method can be an effective approach to select a subset of ...
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... performance metrics. This is because the selected simu- lations, based on the quantiles of the SPA metric distribution, will also represent similar quantiles in the distribution of performance metrics under natural climate variability (as represented by the 3,880 stochastic simulations) if the fits in Figs. 2(a and c) are very precise. As seen in Figs. 2(a and c), the relationship between res- ervoir performance and the SPA metric is clearly linear with some noise (Pearson's r value of −0.71 and 0.85 for reliability and vul- nerability, respectively). The strong fit suggests that the SPA method can be an effective approach to select a subset of stochastic simulations for the stress test. Given ...
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... for the stress test. Given the noise in the relationships, it is recognized that the approach is imperfect and does not guarantee that the selected climate sequences will represent the full range of system performance that could arise under natural variability. This is seen by the nonmonotonic progression of the selected simula- tions in Figs. 2(a and c) along the reliability and vulnerability axes. However, the benefits of computational efficiency may be substan- tial and the selected climate sequences still span most of the distribution of system performance across the original stochastic ensemble. Results for identifying the dth drought statistic (i.e., the minimum d-year moving sum ...
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... 2(b and d) illustrate the relationship between system per- formance metrics and the minimum 2-year precipitation values across all stochastic simulations, with selected quantiles (0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 0.9, 0.95, and 0.99) of the 2-year drought metric highlighted. The relationships in Figs. 2(b and d) appear linear within the limits of the tested data, but as expected, they are more noisy than for the SPA metric in Figs. 2(a and c). This is because metrics derived from inflows are bound to predict system performance with greater accuracy than those derived directly from climate data. As such, Method 1 is more likely to choose an ...
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... minimum 2-year precipitation values across all stochastic simulations, with selected quantiles (0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 0.9, 0.95, and 0.99) of the 2-year drought metric highlighted. The relationships in Figs. 2(b and d) appear linear within the limits of the tested data, but as expected, they are more noisy than for the SPA metric in Figs. 2(a and c). This is because metrics derived from inflows are bound to predict system performance with greater accuracy than those derived directly from climate data. As such, Method 1 is more likely to choose an appropriate subset of stochastic sim- ulations for the stress test than Method 2. However, Method 2 does still provide some utility in ...
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The risk of climate change with negative impacts on water resources and water management has stimulated many hydrological impact studies in recent decades. General Circulation Models (GCM) are often used to provide regional climate scenarios. Unfortunately, regional results between different GCMs differ significantly. In this paper, the uncertainty...
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Citations
... Wilks and Wilby (1999) Srikanthan and McMahon (2001) Stress testing A special case of sensitivity analysis involving evaluation of how a system performs in different combinations of stressors (i.e., combinations of future conditions) and with an increased focus on identifying combinations that lead to undesirable outcomes. Whateley et al. (2016) Stressor Aspects of a system's inputs that could change in the future and may cause undesirable outcomes. Examples include climatic stressors (such as precipitation or temperature) and non-climate stressors. ...
Together with other “bottom‐up” methods, climate stress testing is becoming a prominent approach for climate change impact assessment of water systems. Compared with traditional approaches, stress testing is: (i) more focused on exploring the vulnerabilities of the system at hand; (ii) potentially more inclusive, being amenable to stakeholder involvement and (iii) well suited to identify robust policy options that better account for the deep uncertainty associated with multiple plausible futures. Stress testing is rapidly evolving and giving rise to new techniques and concepts, but few articles provide an accessible overview that can serve as an introduction to the field. Here, we review the underlying principles and concepts of climate stress testing, providing a guide to the main decisions involved in practical application. Topics include selection of stressors, characterizing and exploring the exposure space and data generation including the use of stochastic data. In a complex world where water decisions are made in the context of wider socio‐ecological systems, stress testing and other bottom‐up methods can support decisions that are not only robust to future uncertainty but also regarded as legitimate by affected communities.
This article is categorized under: Engineering Water > Sustainable Engineering of Water
Science of Water > Water and Environmental Change
Water and Life > Stresses and Pressures on Ecosystems
... On the other hand, these models have great difficulty in reproducing high and lowfrequency climate variability and their simulations produce many uncertainties about the evolution of climate variability (Steinschneider and Brown, 2013). Various downscaling techniques have been proposed to mitigate some of these problems (Whateley et al., 2016). ...
Runoff and soil erosion are very pronounced in the Western European Loess Belt. In this study, the distributed physically-based model CLiDE is calibrated, validated, and applied to a catchment of this area (Dun, NW, France) to assess the hydro-sedimentary impacts of climate change scenarios. Despite considerable progress over the last decade in the study of runoff and soil erosion in the context of climate change, the effects of changes in the temporal variability of precipitation remain poorly understood, especially at the scale of a river basin. To examine these relationships more closely, we developed a stochastic weather generator to individually adjust the components that structure the temporal variability of rainfall. The climate scenarios considered represent projections to the year 2100 of the temporal variability of rainfall over NW Europe. The scenarios are based on historical daily rainfall records (1990-2012) and 4 exploratory assumptions: a 50 % decrease in the interannual rainfall regime (scenario 6yD), a 100 % increase in the interannual rainfall regime (scenario 6yI), a 50 % increase in the seasonal rainfall regime (scenario 1yI) and a 50 % increase in the synoptic rainfall regime (scenario 3dI). Simulated daily water and sediment discharges and erosion/deposition maps for each scenario are compared to those simulated for the situation without changes in rainfall. The time series were aggregated over different time intervals to allow for a multi-scale analysis of the differences. The results indicate that the model provides a satisfactory prediction of the catchment's water and sediment discharges, especially over the calibration period. Increased climate variability, whether on a synoptic (3dI), seasonal (1yI) or interannual (6yI) scale, leads to increased runoff and erosion. Increasing the synoptic rainfall variability (3dI) leads to the largest increase in mean annual runoff and erosion. Only the reduction of the interannual rainfall variability (6yD) provokes the decrease of these values.
... Ces modèles ont d'autre part beaucoup de mal à reproduire la variabilité haute et basse fréquence du climat et leurs simulations sont entachées de nombreuses incertitudes concernant l'évolution de la variabilité climatique (Steinschneider et Brown, 2013). Diverses procédures de réduction d'échelle ont été proposées pour atténuer certains de ces problèmes (Whateley et al., 2016) (Lempert et Groves, 2010). ...
Nous ne comprenons pas encore complètement le rôle que les caractéristiques physiques des surfacesexercent sur la réponse hydro-sédimentaire des bassins versants aux précipitations. L’objectif de ce travailde thèse est donc de comprendre de quelle manière les flux hydro-sédimentaires, générés par le climat, sontmodulés par les caractéristiques des surfaces continentales, à court et long terme. Cette question a étéabordée en considérant de nombreux bassins versants aux conditions climatiques et aux caractéristiquesphysiques diverses. L'approche retenue est basée sur l’application conjointe de deux outils : la modélisationet les méthodes de traitement du signal. Les méthodes de traitement du signal (fonction d’autocorrélation etspectre de Fourier) ont permis de caractériser la variabilité temporelle des flux hydro-sédimentaire. Elles ontpermis d’établir un lien entre le comportement hydro-sédimentaire des bassins versants et leurs propriétésphysiques et climatiques. Le fonctionnement hydro-sédimentaire de deux cents quarante-trois bassinsversants synthétiques, simulé avec le modèle distribué à base physique CAESAR-Lisflood/CLiDE (Coulhardet al., 2013), a commencé par être analysé. Ces bassins versants, dont les caractéristiques physiques sontparfaitement contrôlées, ont permis une analyse de sensibilité méthodique. Outre la taille et la forme dubassin versant, la procédure de génération de bassins synthétiques, spécialement développée pour ce travailde thèse, a permis d'ajuster cinq paramètres de manière indépendante : la densité de drainage, l'intégralehypsométrique, la pente moyenne du chenal principal, l'occupation des sols et la granulométrie. Uncomportement plus lisse et moins intermittent du flux sédimentaire est mis en évidence pour des bassinsvégétalisés à forte pente, hypsométrie et densité de drainage et à granulométrie fine et homométrique. Encomplément, le modèle a été appliqué à cinq bassins versants réels (le Laval, le Brusquet, l’Orgeval, le Dunet l’Austreberthe) afin d’analyser les processus et les flux hydro-sédimentaires se produisant dans desenvironnements plus complexes. L’analyse des mesures in-situ de flux hydro-sédimentaire disponibles pources bassins a permis de corroborer certains des résultats obtenus pour les bassins synthétiques.Parallèlement, la capacité de CAESAR-Lisflood/CLiDE, après calibration, à reproduire la dynamique hydrosédimentaire des cinq bassins a été évaluée. La version calibrée du modèle a finalement été employée pourexplorer, pour les bassins versants du Dun et de l’Austreberthe, des scénarios de changementsenvironnementaux comme la modification du mode d'occupation des surfaces ou bien la modification dusignal climatique d'entrée. Les résultats montrent une évolution importante des flux hydro-sédimentaires pourles scénarios climatiques testés.
... A critical challenge remains in defining system performance metrics and associated thresholds, which requires deep cooperation with managers and stakeholders (Sauquet et al., 2019). Besides, the generation of plausible and realistic climate scenarios requires the effort of the scientific community (e.g., Culley et al., 2019;Guo et al., 2018;Whateley et al., 2016). ...
Understanding the vulnerability of water management under global change is the premise for designing adaptation actions. A comprehensive assessment of current water management vulnerability to future changes hinges on new tools that are able to represent human impact on water resources and innovative frameworks that are able to generate new insights to inform adaptation designing. Therefore, this dissertation sets out to (1) develop and improve models to represent water resources, water demand, and water management in an integrated hydrological modelling framework; (2) apply a "scenario-neutral" bottom-up framework and a "scenario-led" top-down framework to identify and investigate plausible vulnerability and impact under global change. These developments and applications are demonstrated by taking the Neste water system in French Pyrenees as a case study.
... Thus, it is neither practical nor possible to test ecological vulnerability to every conceivable change. Studies must choose carefully, ideally identifying the salient stressors or range of changes that will most expose future vulnerability (Whateley et al., 2016). ...
Climate change is projected to impact multiple components of the flow regime. However, changes in some ecologically important aspects of flow seasonality and variability are not well‐represented by global climate models. We used a stress testing method and global sensitivity analysis to investigate whether interactions between five different, but plausible, change “dimensions” (hydroclimatic variables or relationships) led to worse ecological outcomes than individual changes. The five dimensions include changes in long‐term average rainfall and temperature, low‐frequency variability of rainfall, seasonality of rainfall, and the rainfall‐runoff relationship. Our case study involved regulated and unregulated sections of the Goulburn River, Australia. We found that four different modeled ecological outcomes (condition of small bodied fish, large bodied fish, in‐channel vegetation, and floodplain vegetation) are most sensitive to changes in long‐term average rainfall. Sensitivity to changes in rainfall seasonality depends on river characteristics and appears to be heavily dampened by regulation and actively managed environmental water. Changes to the rainfall‐runoff relationship (which may be triggered by long‐term drying) were found to greatly influence ecological outcomes, but remain poorly understood. However, when considering the worst outcomes that are likely to present severe threats to ecological survival, all five dimensions were significant. These worst outcomes only manifest under certain combinations of changes with interactive effects. These joint interactions have implications for climate risk assessments that do not consider multiple dimensions of change, particularly those aimed at evaluating and mitigating severe threats or extinction probability.
... Climate uncertainty in future conditions has contributed to the development of scenario-neutral or decision scaling approaches Brown and Wilby, 2012), although these methods are not solely suited to climate change analysis. Unfortunately, their computational requirements can quickly become demanding, particularly when assessing complex systems with multiple objectives (Whateley et al., 2016). To overcome this, many modelers use simple statistical meta-models that are parameterized based on a few simulations of the more detailed system model (Poff et al., 2016;Turner et al., 2014;Whateley et al., 2016). ...
... Unfortunately, their computational requirements can quickly become demanding, particularly when assessing complex systems with multiple objectives (Whateley et al., 2016). To overcome this, many modelers use simple statistical meta-models that are parameterized based on a few simulations of the more detailed system model (Poff et al., 2016;Turner et al., 2014;Whateley et al., 2016). However, these simple methods may obscure system dynamics and introduce additional uncertainty into modelling outputs, again, especially for ecological purposes where rates of species decline can depend on initial conditions (Bond et al., 2018;Wang et al., 2018). ...
... Further still, if management responses are to be simulated, this effectively adds another 'dimension' to the analysis. There are already examples where 'bottom-up' climate impact assessments for freshwater ecosystems have faced challenges due to the computational requirements of water resource models (John et al., 2020;Whateley et al., 2016). Our monthly modelling and disaggregation approach has the potential to significantly reduce the computational burden of undertaking climate change risk assessments that explore large ranges of uncertainty and the effect of natural variability, and can be combined with existing techniques such as climate screening (Steinschneider et al., 2015). ...
Daily timescale hydrological information is important for many purposes such as flood estimation, predicting the consequences of catchment management and meeting the needs of freshwater ecology. In hydrological assessments, daily timestep modelling is typically used because of the availability of daily data and many of the processes governing impacts occur at this timescale. However, daily models can suffer from poor performance in certain contexts (e.g. drier climates), and their computational requirements can make it difficult to efficiently explore many sources of uncertainty in some situations, such as understanding the impacts of climate change in larger water resource systems. Here, we test an alternate approach based on monthly modelling with a post-processing step involving monthly-to-daily disaggregation using historic flow patterns conditioned on soil moisture estimates. We apply our approach to 214 catchments across Australia representing a wide range of climate and hydrological conditions, and assess outcomes for multiple objectives spanning water supply, flood magnitude and freshwater ecological outcomes, and validate performance over an extreme multi-year drought with substantially different rainfall and streamflow characteristics. Our results show that for many metrics including sustained low flows, annual flow maxima, and high and low flow spells, the results based on monthly hydrologic modelling with daily disaggregation are generally better than those based on daily hydrological modelling. This was especially true for ecologically relevant flow metrics. In addition, the disaggregation approach fared better than the daily model when extrapolating to the multi-year dry period. Our approach also has the potential to greatly reduce the effort required to explore uncertainty in large river systems.
... The quantitative model or decision-support tool co-created with stakeholders provides a frame for making stresstests of existing policies and potential innovations, and thus analyse the region's vulnerabilities, e.g. water supply reliability (Whateley et al., 2016). By modelling the performance of adaptation and mitigation plans, infrastructure projects, business plans, and investment options for utilities with their links across economic sectors, and embedding them into socio-economic scenarios that are analysed under climate change scenarios, it is possible to assess their efficiency and characterize their sensitivity and vulnerability across nexus resources. ...
The water-energy-land nexus requires long-sighted approaches that help avoid maladaptive pathways to ensure its promise to deliver insights and tools that improve policy-making. Climate services can form the foundation to avoid myopia in nexus studies by providing information about how climate change will alter the balance of nexus resources and the nature of their interactions. Nexus studies can help climate services by providing information about the implications of climate-informed decisions for other economic sectors across nexus resources. First-of-its-kind guidance is provided to combine nexus studies and climate services. The guidance consists of ten principles and a visual guide, which are discussed together with questions to compare diverse case studies and with examples to support the application of the principles.
... The inconsistent hydrological series is synthetized by utilizing distribution synthesis method (Xie et al. 2009). The Monte Carlo method is used to generate pure stochastic series that can meet the rule of randomness (Lombardo et al. 2017;Sirangelo et al. 2017;Whateley et al. 2016). The stochastic components and deterministic components are numerically synthetized to obtain the sample series. ...
Drought occurrence and its related impacts are a major concern in many basins throughout the world. Reservoirs play a very important role in drought resistance. Compared with the reservoir flood limit water level, the drought limit water level belongs to a new concept. This paper took the Yuqiao reservoir as the study area and proposed a new method to determine the drought limit water level under changing environment. Firstly, the Mann-Kendall (M-K) method and cluster analysis method were employed to test the trend and change point of the series based on the runoff series of Yuqiao reservoir. On this basis, the runoff frequency curve and design runoff process under current condition were obtained by Pearson-III frequency analysis. Secondly, copula function was used to analyze the synchronous-asynchronous encounter probability of rich-poor runoff of Yuqiao reservoir and Panjiakou reservoir. The available transferred volume of Yuqiao reservoir in dry year was analyzed. Finally, according to the runoff and available transferred volume, the total inflow of Yuqiao reservoir in dry season was calculated. Combining water demand and total inflow of Yuqiao reservoir, the drought limit water level was calculated by month to month. The study results can provide necessary technique support for reservoir drought emergency management.
... In addition to downscaling GCM output, approaches are needed to examine potential precipitation variability under current and future conditions. One approach utilizes GCM output to create a stochastic weather generator model (Harris et al. 2014;Wilks 2010;Lee and Jeong 2014;Whateley et al. 2016), an approach that is also being applied in Philadelphia. Arnbjerg-Nielsen et al. (2013) discuss several types of stochastic weather generators. ...
Statistically downscaled global climate model (GCM) precipitation output is available for Philadelphia, but the temporal resolution is too low for direct use in model-based urban stormwater applications. Additionally, GCM output for Philadelphia does not accurately represent local storm intensities and durations. To address these limitations, this study presents an innovative approach employed by the Philadelphia Water Department (PWD) to transform GCM output into actionable science that can directly inform planning, design, and engineering applications, including hydrologic and hydraulic (H&H) modeling and intensity-duration-frequency curve development. This approach uses GCM output for current (1995-2015) and future (2080-2100) conditions under a certain greenhouse gas emission trajectory to develop delta change factors based on season and storm size. These factors are then used to create a plausible future hourly time series. A stochastic generator was also developed that utilizes the adjusted future time series to explore potential variability in projected precipitation patterns. The approach presented in this study is practical and transferable, addressing the need for actionable climate change information in the field of water resource management.
... Based on the comprehensive co-evolution model proposed in this paper, the adaptability criterion for urban WRS was obtained ( Table 6). The coordination grade standard for WRS was obtained using the median segmentation method (Whateley et al. 2016) (Table 7). ...
Studying the complex adaptability of regional water resources systems (WRS) plays an important role in promoting the sustainable utilization of water resources and improving the adaptation of WRS to environmental change. This study proposed a comprehensive co-evolution model, based on the conditions of the elements and on the mechanism of their interaction, to study the adaptive development of WRS. Using the model, the survival fitness of each subsystem, the coordination degree between each subsystem, and the survival fitness of the WRS were obtained, and the main factors that affect the adaptation of the WRS were analyzed. Shandong Province in China was used as an example. The results showed that during 2006–2015, the average annual survival fitness of the resource, social, economic, and ecological subsystems was 0.257, 0.282, 0.257, and 0.251, respectively, which indicated a low adaptability for each subsystem. The coordination degree between each subsystem (resource–society, resource–economy, resource–ecology, social–economic, social–ecological, and economic–ecological) was 0.319, 0.355, 0.334, 0.364, 0.333, and 0.351, respectively, which indicated minimal coordination between each subsystem. The average annual survival fitness of the WRS was 0.551, and the adaptability of the WRS was classified as basic. Further analysis revealed that the coordination problem caused by the interaction of the elements in each subsystem was responsible for the low adaptability. The coordination problem, therefore, places severe constraints on the adaptive development of WRS. Therefore, solving the problem of coordination between elements is fundamental to improving the adaptability of WRS and promoting its sustainable development.
