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Since the approval of the Agenda 2030, researchers and policy makers have pointed out the need to understand interactions among the Sustainable Development Goals (SDGs)—suggesting that progress or the lack of progress toward one goal will affect other goals through systemic interactions, producing synergies and trade-offs. However, most of the methods used to account for these interactions rely on hard systems thinking approaches, which are limited by the absence of needed data below national levels. Moreover, a general lack of data also constrains the scope of analysis to the 17 Goals, ignoring their 169 underlying targets. Given these challenges, we report on an experiment using an example of a soft systems thinking methodology: the SDG Synergies approach, which is based not only on available information but also on the elicitation of stakeholder and expert opinions. Thus, the approach allows for analysis of target-to-target interactions at subnational scales. The study, the first of its kind, assessed interactions at two scales: the national level in Colombia and the subnational level in the department of Antioquia. The results reveal profound differences between the two scales, suggesting that national-scale analysis of SDG interlinkages is not certain to capture local-level realities. The findings raise important issues for understanding and managing cross-scale interactions. Our work suggests that soft systems thinking is more appropriate for assessing SDG interactions because such an approach lends itself to conducting target-level analysis at various scales in the face of limited data availability.

A climatically driven, water system modeling framework that captures a full range of interacting components at necessary spatiotemporal scales was developed for the Southwestern United Stat...

A number of large hydropower dams are currently under development or in an advanced stage of planning in the Magdalena River basin, Colombia, spelling uncertainty for the Mompós Depression wetlands, one of the largest wetland systems in South America at 3400 km2. Annual large-scale inundation of floodplains and their associated wetlands regulates water, nutrient, and sediment cycles, which in turn sustain a wealth of ecological processes and ecosystem services, including critical food supplies. In this study, we implemented an integrated approach focused on key attributes of ecologically functional floodplains: (1) hydrologic connectivity between the river and the floodplain, and between upstream and downstream sections; (2) hydrologic variability patterns and their links to local and regional processes; and (3) the spatial scale required to sustain floodplain-associated processes and benefits, like migratory fish biodiversity. The implemented framework provides an explicit quantification of the nonlinear or direct response relationship of those considerations with hydropower development. The proposed framework was used to develop a comparative analysis of the potential effects of the hydropower expansion necessary to meet projected 2050 electricity requirements. As part of this study, we developed an enhancement of the Water Evaluation and Planning system (WEAP) that allows resolution of the floodplains water balance at a medium scale (∼ 1000 to 10 000 km2) and evaluation of the potential impacts of upstream water management practices. In the case of the Mompós Depression wetlands, our results indicate that the potential additional impacts of new hydropower infrastructure with respect to baseline conditions can range up to one order of magnitude between scenarios that are comparable in terms of energy capacity. Fragmentation of connectivity corridors between lowland floodplains and upstream spawning habitats and reduction of sediment loads show the greatest impacts, with potential reductions of up to 97.6 and 80 %, respectively, from pre-dam conditions. In some development scenarios, the amount of water regulated and withheld by upstream infrastructure is of similar magnitude to existing fluxes involved in the episodic inundation of the floodplain during dry years and, thus, can also induce substantial changes in floodplain seasonal dynamics of average-to-dry years in some areas of the Mompós Depression.

In Bolivia, since 2006 the Ministry of Environment and Water, through the National Watershed Plan, has developed the conceptual framework and national policy for Watershed Management. At present, this national policy is still in the process of learning and construction from its application in various river basins, principally through the development of Watershed Master Plans.Three principles guide the development of this national planning effort: i. the recognition of the growing dependence on participatory processes as a forum to identify and enable legitimate water management and governance options, ii. the need to plan for an uncertain future caused by climate change and other societal prerogatives iii. the systemic analysis of the territory incorporating biophysical, sectoral and regional interactions.Here we present results and lessons learned of this process in the formulation of the Master Plan of the Río Rocha Basin (PDCR); With a population of ~ 1,500,000 people (13% of Bolivia’s population), the basin has high levels of water scarcity that feed an intricate network of conflicts related to access, governance, and environmental degradation. The PDCR is a planning opportunity to enable the necessary conditions to resolve current conflicts and set the foundation of sustainable water management.Robust decision support (RDS) has been adopted as a guiding framework, constructing a participatory process that considers uncertainties and strategies within an array of management options for the system. To accommodate the large disparities in water access across interests represented at different regions and scales of the Rio Rocha Basin, we implemented two innovations in the RDS process: first, a set of 24 quantitative indices that can operate at several nested scales of planning sub-units (i.e. from independent irrigation units or household water supply service areas, to the entire river basin), and second the use of an interactive “hard-coupled” decision dashboard to the Water Evaluation and Planning System (WEAP). In combination, this innovations enabled a diverse audience of actors to: i) explore the positive and negative interactions of water management, production systems, hazards and risks management, and ecosystem functions ii) identify disparities in the performance of a proposed plan between scales and ii) analyze and compare different management strategies interactively to improve outcomes and identify and mitigate emerging regional or sectorial conflicts.As a result, the PDCR established a set of regional and intersectoral actions for 2025 and 2040, which integrate infrastructure, efficiency, pollution control, and territorial and productive planning actions, accompanied by institutional strengthening and capacity development measures. The plan expects to increase access and coverage of the demand for safe water, improve irrigation access, enable long term sustainable exploitation of groundwater and establish synergies with the existing sanitation plan to achieve additional improvements in the environmental quality of the Rio Rocha.

The hydrologic nonstationarity and uncertainty associated with climate change requires new decision-making methods to incorporate climate change impacts into flood frequency and flood risk analyses. To aid decision-making under climate change, we developed a bottom-up approach for assessing the performance of flood management systems under climate uncertainty and nonstationarity. The developed bottom-up approach was applied to the American River, CA, USA flood management system by first identifying the sensitivity and vulnerability of the system to different climates. To do this, we developed a climate response surface by calculating and plotting Expected Annual Damages (EAD, $/year) under different flood regimes. Next, we determined a range of plausible future climate change and flood frequency scenarios by applying Bayesian statistical methods to projected future flows derived from a Variable Infiltration Capacity (VIC) model forced with Global Circulation Model (GCM) output. We measured system robustness as the portion of plausible future scenarios under which the current flood system could meet its performance goal. Using this approach, we then evaluated the robustness of four proposed management strategies in the 2012 Central Valley Flood Protection Plan in terms of both flood risk and cost-effectiveness, to assess the performance of the strategies in the face of climate risks. Results indicated that the high sensitivity of the expected damages to changes in flood regimes makes the system extremely vulnerable to a large portion of the plausible range of future flood conditions. The management strategy that includes a combination of nature-based flood management actions along with engineered structures yields the greatest potential to increase system robustness in terms of maintaining EAD below an acceptable risk threshold. However, this strategy still leaves the system vulnerable to a wide range of plausible future conditions. As flood frequency regimes increase in intensity from the current conditions, the cost-effectiveness of the management strategies increases, to a point, before decreasing. This bottom up analysis demonstrated a viable decision-making approach for water managers in the face of uncertain and changing future conditions. Neglecting to use such an approach and omitting climate considerations from water resource planning could lead to strategies that do not perform as expected or which actually lead to mal-adaptations, increasing vulnerability to climate change.

Each actor evaluating potential management strategies brings her/his own distinct set of objectives to a complex decision space of system uncertainties. The diversity of these objectives and uncertainties requires detailed and rigorous analyses that respond to multifaceted challenges. The utility of this information depends on the accessibility of scientific information to decision makers. This paper demonstrates data visualization tools for presenting scientific results to decision makers in two case studies, La Paz/El Alto, Bolivia, and Yuba County, California. Visualization output from the case studies combines spatiotemporal, multivariate and multirun/multiscenario information to produce information corresponding to the objectives and uncertainties described by key actors. These tools can manage complex data and distill scientific information into accessible formats. Using the visualizations, scientists and decision makers can navigate the decision space and potential objective trade-offs to facilitate discussion and consensus building. These efforts can help identify stable negotiated agreements between different stakeholders. We present a Decision Space Visualization (DSV) that condenses model results to tackle complex water management challenges.DSV enables comparisons between potential management options against many uncertainties.It allows exploring results in meaningful formats for decision makers that answers their most pressing questions.The case studies presented suggests that DSV stimulates active engagement from stakeholders.

Climate change can affect a region's environment and economy through changes in water resource flows and allocations. The hydrologic and economic components of these impacts require complex models to reflect both the environment's physical and individuals' behavioral responses to climate change. This paper describes a model that combines the strengths of the State Wide Economic Agricultural Production Model (SWAP), an agricultural economic optimization model, and Water Evaluation and Planning (WEAP), a climate-driven hydrological model. A step function approximation of water demand curves from SWAP is used in an iterative search process to estimate crop land allocation based on annual regional water availability and economic value. SWAP value functions serve as input for an optimal discretization of water demand functions. The methodological integration of the SWAP and WEAP models creates the EconWEAP model. This paper shows the improved analytic ability of this integration by comparing agricultural revenues from WEAP vs. EconWEAP. Results for EconWEAP runs in the California's Central Valley show a significant increase in revenues for the Central Valley, maintaining the same hydrology, through the economically optimal allocation of water. This integration approach can be applied to other types of economic and hydrologic models.

River basin planning in Bolivia is a relatively new endeavor that is primed for innovation and learning. One important learning opportunity relates to connecting watershed planning to processes within other planning units (e.g., municipalities) that have water management implications. A second opportunity relates to integrating watershed management, with a focus on land-based interventions, and water resources management, with a focus on the use and control of surface and groundwater resources. Bolivia&rsquo, s River Basin Policy and its primary planning instrument, the River Basin Master Plan (PDC in Spanish), provide the relevant innovation and learning context. Official guidance related to PDC development lacks explicit instructions related to the use of analytical tools, the definition of spatially and temporally dis-aggregated indicators to evaluate specific watershed and water management interventions, and a description of the exact way stakeholders engage in the evaluation process. This paper describes an effort to adapt the tenets of a novel planning support practice, Robust Decision Support (RDS), to the official guidelines of PDC development. The work enabled stakeholders to discern positive and negative interactions among water management interventions related to overall system performance, hydrologic risk management, and ecosystem functions, use indicators across varying spatial and temporal reference frames, and identify management strategies to improve outcomes and mitigate cross-regional or inter-sectorial conflicts.

Two trends currently shape water resources planning and decision making: reliance on participatory stakeholder processes to evaluate water management options, and growing recognition that deterministic approaches to the evaluation of options may not be appropriate. These trends pose questions regarding the proper role of information, analysis, and expertise in the inherently social and political process of negotiating agreements and implementing interventions in the water sector. The question of how one might discover the best option in the face of deep uncertainty is compelling. The question of whether the best option even exists to be discovered is more vexing. While such existential questions are not common in the water management community, they are not new to political theory. This paper explores early classical writing related to issues of knowledge and governance as captured in the work of Plato and Aristotle, and then attempts to place a novel, analysis-supported, stakeholder-driven water resources planning and decision making practice within this philosophical discourse, making reference to current decision theory. Examples from the Andes and California, where this practice has been used to structure participation by key stakeholders in water management planning and decision-making, argue that when a sufficiently diverse group of stakeholders is engaged in the decision making process expecting the discovery of the perfect option may not be warranted. Simply discovering a consensus option may be more realistic. The argument touches upon the diversity of preferences, model credibility and the visualization of model output required to explore the implications of various management options across a broad range of inherently unknowable future conditions.

Water scientists often find themselves interacting with decision-makers with varying levels of technical background. The sustainable management of water resources is complex by nature, and future conditions are highly uncertain, requiring modeling approaches capable of accommodating a variety of parameters and scenarios. Technical findings from these analyses need to be positioned and conducted within the governance institutions to ensure decision-makers utilize them. This paper examines the water resource challenges for a large basin in northern Patagonia, Argentina and utilizes the Robust Decision Support (RDS) framework to evaluate trade-offs and strategies in a participatory process that included researchers and decision-makers. Integrated water resources models using simulation modeling and decision space visualization show significant climate change impacts, which are augmented with irrigated agriculture expansion and increasing hydropower production.

© 2015, Springer Science+Business Media Dordrecht. This paper is among the first to report on the full integration of basin-scale models that include projections of the demand and supply of water and energy for residential, commercial, industrial, and agricultural sector users. We link two widely used regional planning models that allow one to study the impact of rising climate variability on water and electricity use in Sacramento, California. Historic data combined with the current energy and water system configuration was used to assess the implications of changes in temperature and precipitation. Climate simulations suggest that electricity imports to the region would increase during hot dry spells, when regional power production is most constrained. In particular, regional imports of electricity would increase over 35 % in hot dry years, assuming a 4 °C increase in average temperature and a 25 % decrease in average precipitation.

A number of large hydropower dams are currently under development or in an advanced stage of planning in the Magdalena River basin, Colombia, spelling uncertainty for the Mompós Depression wetlands, one of the largest wetland systems in South America. Annual large-scale inundation of floodplains and associated wetlands regulates water-, nutrient-, and sediment cycles, which in turn sustain a wealth of ecological processes and ecosystem services, including critical food supplies. In this study, we present a comparative analysis of the potential effects of hydropower expansion to meet projected electricity requirements by 2050, in terms of 1) basin-level implications of cumulative changes in streamflow regime, sediment trapping, and loss of river connectivity, and 2) the impact of upstream regulation on the hydrologic dynamics of the Mompós Depression wetlands at a monthly to decadal scale. To this end, we developed an enhancement of the Water Evaluation and Planning system (WEAP) that allows resolution of the Mompós Depression floodplains water balance at a medium scale (~1000 to 10 000 km2) and evaluation of the potential impacts of upstream water management practices. Our results indicate that potential additional impacts of new hydropower infrastructure with respect to baseline conditions can range up to one order of magnitude between scenarios that are comparable in terms of energy capacity. Fragmentation of connectivity corridors between lowland floodplains and upstream spawning habitats and reduction of sediment loads show the greatest impacts, with potential reductions of up to 97.6 and 80 %, respectively, from pre-dam conditions. In some development scenarios, the amount of water regulated and withheld by upstream infrastructure is of similar magnitude to existing fluxes involved in the episodic inundation of the floodplain during dry periods and, thus, can also induce substantial changes in floodplain seasonal dynamics of average-to-dry years in some areas of the Mompós Depression.

En este artículo se presenta un enfoque útil para la modelación hidrológica de cuencas de suministro de agua potable incluyendo incertidumbres como el cambio climático. La modelación se realizó bajo la plataforma Water Evaluation And Planning System (WEAP) y comprende aporte de glaciares, precipitación-escorrentía, infraestructura hidráulica y demanda urbana. El estudio caso está referido a los sistemas de agua de las ciudades de La Paz y El Alto que están ubicadas en la región Occidental de Bolivia. Estas ciudades son abastecidas de agua por pequeñas cuencas glaciares de la Cordillera Real. Por el crecimiento acelerado de la población especialmente en la ciudad de El Alto existen problemas en el abastecimiento de agua, y esto podría exacerbase por los impactos negativos del cambio climático por ejemplo el retroceso de los glaciares. Existe una necesidad urgente de conocer los posibles impactos del cambio climático, para esto es necesario tener un mayor conocimiento del potencial hídrico de las cuencas. Sin embargo, existen bastantes limitaciones respecto a la disponibilidad y calidad de los datos hidro-climáticas. Asimismo, no se cuenta con datos de escenarios de clima futuro a la escala de las cuencas que permitan modelar los posibles cambios esperados. En ese sentido en esta investigación se desarrolló una herramienta útil para la planificación de recursos hídricos bajo la incertidumbre de datos históricos y futuros. Los resultados para un horizonte de tiempo 2010-2050 muestran que los glaciares podrían desaparecer en los próximos 30 años, y esto podría tener implicaciones en la respuesta hidrológicas de las cuencas con la reducción de la oferta de agua. La ciudad de El Alto sería la más afectada, ya que se advierten serios problemas en el abastecimiento de agua. Se debe pensar en estudiar estrategias de nuevo almacenamiento de agua como medidas de adaptación al cambio climático.

This paper explores the welfare costs associated with drought plan transactions between a public municipal water agency, the El Dorado Irrigation District (EID) in California in the USA and its customers. The EID imposes a tiered pricing plan for municipal customers, which was analyzed as a discrete continuous choice (DCC) model by water users within a climate driven water evaluation and planning (WEAP) model of the EID water system. The DCC is subsequently used to estimate the compensating variation (CV) measure of the loss of consumer welfare in the case where a customer does not receive water that matches a preferred level of demand. In addition to monetized welfare loss, we look at other metrics of performance such as reservoir storage and hydropower generation. For the drought-of-record under full build-out, results show that the welfare loss to EID customers from the imposed drought plan is far less than if no drought plan were in place. This suggests that current consumption is well beyond essential needs and, without a drought plan, water shortages in the later period of a drought would generate a much greater welfare loss. Most of the cost associated with the drought plan is born by EID in the form of reduced revenues.

Urban areas in the Lake Victoria (LV) region are experiencing the highest growth rates in Africa. As efforts to meet increasing demand accelerate, integrated water resources management (IWRM) tools provide opportunities for utilities and other stakeholders to develop a planning framework comprehensive enough to include short term (e.g. landuse change), as well as longer term (e.g. climate change) scenarios. This paper presents IWRM models built using the Water Evaluation And Planning (WEAP) decision support system, for three towns in the LV region – Bukoba (Tanzania), Masaka (Uganda), and Kisii (Kenya). Each model was calibrated under current system performance based on site visits, utility reporting and interviews. Projected water supply, demand, revenues and costs were then evaluated against a combination of climate, demographic and infrastructure scenarios up to 2050. Our results show that water supply in all three towns is currently infrastructure limited; achieving existing design capacity could meet most projected demand until 2020s in Masaka beyond which new supply and conservation strategies would be needed. In Bukoba, reducing leakages would provide little performance improvement in the short-term, but doubling capacity would meet all demands until 2050. In Kisii, major infrastructure investment is urgently needed. In Masaka, streamflow simulations show that wetland sources could satisfy all demand until 2050, but at the cost of almost no water downstream of the intake. These models demonstrate the value of IWRM tools for developing water management plans that integrate hydroclimatology-driven supply to demand projections on a single platform.

a b s t r a c t We assess the potential effects of climate change and adaptive management on irrigation water supply in the Cache Creek watershed in California. Our model, built using the Water Evaluation And Planning (WEAP) system, is calibrated using historical data (1971-2000) on streamflow, irrigation deliveries, and reservoir operations. We examine three adaptation scenarios to 2099: (1) changes in cropping patterns based on econometric forecasts, (2) a shift toward a more diversified and water-efficient cropping pat- terns, and (3) a combination of irrigation technology improvements and changes in cropping patterns. Results show irrigation demand increasing by 26% and 32% under B1 and A2 baseline climate scenarios respectively in the latter part of the century under baseline climate scenarios. Irrigation water supply from upstream reservoir releases is less vulnerable, because of increased spring precipitation upstream. However, legal limits on reservoir releases mean that increased demand can only be met by increasing groundwater extraction. Increases in demand from climate change alone exceed applied water reduc- tions from changing cropping patterns by an order of magnitude. Maximum applied water savings occur by combining a diversified water-efficient cropping pattern with irrigation technology improvements, which decreases demand to levels 12% below the historical mean, thereby also reducing groundwater pumping.

Spring-run Chinook salmon (Oncorhynchus tshawytscha) are particularly vulnerable to climate change because adults over-summer in freshwater streams before spawning in autumn. We examined streamflow and water temperature regimes that could lead to long-term reductions in spring-run Chinook salmon (SRCS) in a California stream and evaluated management adaptations to ameliorate these impacts. Bias-corrected and spatially downscaled climate data from six general circulation models and two emission scenarios for the period 2010–2099 were used as input to two linked models: a water evaluation and planning (WEAP) model to simulate weekly mean streamflow and water temperature in Butte Creek, California that were used as input to SALMOD, a spatially explicit and size/stage structured model of salmon population dynamics in freshwater systems. For all climate scenarios and model combinations, WEAP yielded lower summer base flows and higher water temperatures relative to historical conditions, while SALMOD yi...

Climate change impacts and potential adaptation strategies were assessed using an application of the Water Evaluation and Planning (WEAP) system developed for the Sacramento River basin and Delta export region of the San Joaquin Valley. WEAP is an integrated rainfall/runoff, water resources systems modeling framework that can be forced directly from time series of climatic input to estimate water supplies (watershed runoff) and demands (crop evapotranspiration). We applied the model to evaluate the hydrologic implications of 12 climate change scenarios as well as the water management ramifications of the implied hydrologic changes. In addition to evaluating the impacts of climate change with current operations, the model also assessed the impacts of changing agricultural management strategies in response to a changing climate. These adaptation strategies included improvements in irrigation technology and shifts in cropping patterns towards higher valued crops. Model simulations suggested that increasing agricultural demand under climate change brought on by increasing temperature will place additional stress on the water system, such that some water users will experience a decrease in water supply reliability. The study indicated that adaptation strategies may ease the burden on the water management system. However, offsetting water demands through these approaches will not be enough to fully combat the impacts of climate change on water management. To adequately address the impacts of climate change, adaptation strategies will have to include fundamental changes in the ways in which the water management system is operated.

Watersheds of the Cosumnes, American, Bear and Yuba (CABY) Rivers in the Sierra Nevada, California, are managed with a complex network of reservoirs, dams, hydropower plants and water conveyances. While water transfers are based on priorities among competing demands, hydropower generation is licensed by the Federal Energy Regulatory Commission (FERC) and regulated by federal and state laws and multi-party agreements. This paper presents an integrated river basin management (IRBM) model for the CABY region, built to evaluate management and regional climate change scenarios using the Water Evaluation and Planning (WEAP) system. We simulated potential impacts of climate warming on hydrology and hydropower production by imposing a fixed increase of temperature (+2, 4 and 6°C) over weekly historical (1981–2000) climate, with all other climate variables unchanged. Results demonstrate that climate warming will reduce hydropower generation if operational rules remain unchanged, making the case for climate change induced hydrological change as a foreseeable future condition to be included in the FERC licensing process. IRBM tools such as the CABY model presented here are useful in deliberating the same.

Young, Charles A., Marisa I. Escobar-Arias, Martha Fernandes, Brian Joyce, Michael Kiparsky, Jeffrey F. Mount, Vishal K. Mehta, David Purkey, Joshua H. Viers, and David Yates, 2009. Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation. Journal of the American Water Resources Association (JAWRA) 45(6):1409-1423. Abstract: The rainfall-runoff model presented in this study represents the hydrology of 15 major watersheds of the Sierra Nevada in California as the backbone of a planning tool for water resources analysis including climate change studies. Our model implementation documents potential changes in hydrologic metrics such as snowpack and the initiation of snowmelt at a finer resolution than previous studies, in accordance with the needs of watershed-level planning decisions. Calibration was performed with a sequence of steps focusing sequentially on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. An assessment of the calibrated streamflows using goodness of fit statistics indicate that the model robustly represents major features of weekly average flows of the historical 1980-2001 time series. Runs of the model for climate warming scenarios with fixed increases of 2°C, 4°C, and 6°C for the spatial domain were used to analyze changes in snow accumulation and runoff timing. The results indicated a reduction in snowmelt volume that was largest in the 1,750-2,750 m elevation range. In addition, the runoff center of mass shifted to earlier dates and this shift was non-uniformly distributed throughout the Sierra Nevada. Because the hydrologic model presented here is nested within a water resources planning system, future research can focus on the management and adaptation of the water resources system in the context of climate change.

A climate-driven water resource model of California’s Sacramento River Basin (SACB) is presented, based on the Water Evaluation and Planning model Version 21 (WEAP21). The model’s configuration, calibration, testing, and limitations are presented. The major contribution includes an integration of the watershed’s surface and subsurface hydrology, consumptive, and nonconsumptive use, and the water management infrastructure and controls that determine how water naturally flows and is managed. The SACB was subdivided into numerous catchments; groundwater basins; irrigated areas; urban/export use; environmental requirements; and canals, diversions, and reservoirs in an attempt to characterize the forces that act on water throughout the basin. A monthly climate time series forced an embedded hydrologic model that simulates runoff, groundwater-surface water interactions, and consumptive agriculture and urban water uses. Results show that the model can reproduce both local and regional water balances, including m...

The Okavango Delta, Botswana, is a major wetland surrounded by the Kalahari Desert. The delta supports a diverse fish fauna that depends on highly seasonal flooding from inflowing rivers, and on the actions of ecosystem engineers (hippopotamuses, elephants, and termites), for creation and maintenance of their habitats. Conflicts in resource use, especially water, are likely to affect fish populations and the Okavango ecosystem in the near future. We present conceptual models of this remarkable aquatic ecosystem in relation to fish and fisheries as the basis for future research and conservation efforts. Developing understanding of the environmental flow requirements of the delta is key to the management of the Okavango Delta as an ecosystem supporting diverse and abundant fish and wildlife. Once developed, this understanding can be used to allocate water within the Okavango watershed.

The Chinook salmon (Oncorhynchus tshawytscha) spawns and rears in the cold, freshwater rivers and tributaries of California’s Central Valley, with four separate seasonal runs including fall and late-fall runs, a winter run, and a spring run. Dams and reservoirs have blocked access to most of the Chinook’s ancestral spawning areas in the upper reaches and tributaries. Consequently, the fish rely on the mainstem of the Sacramento River for spawning habitat. Future climatic warming could lead to alterations of the river’s temperature regime, which could further reduce the already fragmented Chinook habitat. Specifically, increased water temperatures could result in spawning and rearing temperature exceedences, thereby jeopardizing productivity, particularly in drought years. Paradoxically, water management plays a key role in potential adaptation options by maintaining spawning and rearing habitat now and in the future, as reservoirs such as Shasta provide a cold water supply that will be increasingly needed to counter the effects of climate change. Results suggest that the available cold pool behind Shasta could be maintained throughout the summer assuming median projections of mid-21st century warming of 2°C, but the maintenance of the cold pool with warming on the order of 4°C could be very challenging. The winter and spring runs are shown to be most at risk because of the timing of their reproduction.

As part of the 2006 Climate Change Report to Governor Schwarzenegger and the California Legislature, an application of the Water Evaluation and Planning (WEAP) system in the Sacramento River Basin was deployed to look at the impact of climate change on agricultural water management and the potential for adaptation. The WEAP system includes a dynamically integrated rainfall runoff hydrology module that generates the components of the hydrologic cycle from input climate time series. This allows for direct simulation of water management responses to climate change without resorting to perturbations of historically observed hydrologic conditions. In the Sacramento River Basin, the four climate time series adopted for the 2006 Climate Change Report were used to simulate agricultural water management without any adaptation and with adaptation in terms of improvements in irrigation efficiency and shifts in cropping patterns during dry periods. These adaptations resulted in lower overall water demands in the agricultural sector, to levels observed during the recent past, and associated reductions in groundwater pumping and increases in surface water allocations to other water use sectors.

Using the latest available General Circulation Model (GCM) results we present an assessment of climate change impacts on California hydrology and water resources. The approach considers the output of two GCMs, the PCM and the HadCM3, run under two different greenhouse gas (GHG) emission scenarios: the high emission A1fi and the low emission B1. The GCM output was statistically downscaled and used in the Variable Infiltration Capacity (VIC) macroscale distributed hydrologic model to derive inflows to major reservoirs in the California Central Valley. Historical inflows used as inputs to the water resources model CalSim II were modified to represent the climate change perturbed conditions for water supply deliveries, reliability, reservoir storage and changes to variables of environmental concern. Our results show greater negative impacts to California hydrology and water resources than previous assessments of climate change impacts in the region. These impacts, which translate into smaller streamflows, lower reservoir storage and decreased water supply deliveries and reliability, will be especially pronounced later in the 21st Century and south of the San Francisco bay Delta. The importance of considering how climate change impacts vary for different temporal, spatial, and institutional conditions in addition to the average impacts is also demonstrated.

There is an emerging consensus in the scientific community that climate change has the potential to significantly alter prevailing hydrologic patterns in California over the course of the 21st Century. This is of profound importance for a system where large investments have been made in hydraulic infrastructure that has been designed and is operated to harmonize dramatic temporal and spatial water supply and water demand variability. Recent work by the authors led to the creation of an integrated hydrology/water management climate change impact assessment framework that can be used to identify tradeoffs between important ecosystem services provided by the California water system associated with future climate change and to evaluate possible adaptation strategies. In spite of the potential impact of climate change, and the availability of a tool for investigating its dimensions, actual water management decision-making processes in California have yet to fully integrate climate change analysis into their planning dialogues. This paper presents an overview of decision-making processes ranked based on the application of a 3S: Sensitivity, Significance, and Stakeholder support, standard, which demonstrates that while climate change is a crucial factor in virtually all water-related decision making in California, it has not typically been considered, at least in any analytical sense. The three highest ranked processes are described in more detail, in particular the role that the new analytical framework could play in arriving at more resilient water management decisions. The authors will engage with stakeholders in these three processes, in hope of moving climate change research from the academic to the policy making arena.

Potential conflicts arising from competing demands of complex water resource systems require a holistic approach to address the tradeoff landscape inherent in freshwater ecosystem service evaluation. The Water Evaluation and Planning model version 21 (WEAP21) is a comprehensive integrated water resource management (IWRM) model that can aid in the evaluation of ecosystem services by integrating natural watershed processes with socio-economic elements that include the infrastructure and institutions that govern the allocation of available freshwater supplies. The bio-physical and socioeconomic components of Battle Creek and Cow Creek, two tributaries of the Sacramento River of Northern California, USA, were used to illustrate how a new hydrologic sub-module in WEAP21 can be used in conjunction with an imbedded water allocation algorithm to simulate the hydrologic response of the watersheds and aid in evaluating freshwater ecosystem service tradeoffs under alternative scenarios.

The Water Evaluation and Planning Version 21 (WEAP21) Integrated Water Resource Management (IWRM) model seamlessly integrates water supplies generated through watershed-scale hydrologic processes with a water management model driven by water demands and environmental requirements and is governed by the natural watershed and physical network of reservoirs, canals, and diversions. This version (WEAP21) extends the previous WEAP model by introducing the concept of demand priorities and supply preferences, which are used in a linear programming heuristic to solve the water allocation problem as an alternative to multi-criteria weighting or rule-based logic approaches. WEAP21 introduces a transparent set of model objects and procedures that can be used to analyze a full range of issues faced by water planners through a scenario-based approach. These issues include climate variability and change, watershed condition, anticipated demands, ecosystem needs, the regulatory environment, operational objectiv...

In order to rigorously examine near surface, field to field interactions between irrigation management regimes and a shallow fluctuating water table, an enhanced deforming finite element (DFE) model was recently developed. The enhanced DFE model, through a process of iteration within each time step, avoids making common assumptions regarding the changing geometry of an aquifer free surface. This paper demonstrates the usefulness and effectiveness of the model by employing it to an irrigated region in the western San Joaquin Valley, Calif., where shallow subsurface tile drains have been installed to control shallow water tables. By virtue of the problems created by the need to dispose off the drainage water, this region has been the focus of several important regional scale modeling exercises, which have evaluated the utility of management strategies, such as source control, groundwater pumping, and land retirement. By refining the focus of the analysis, the enhanced DFE model is found to be able to show that both sources control and managed pumping could be more effective drainage control strategies than predicted based on the results of regional models.

RAND researchers and collaborators present a comprehensive approach for water utilities to assess climate risks to their systems and evaluate adaptation strategies. The approach, based on Robust Decision Making, is demonstrated through pilot studies with two water utilities: Colorado Springs Utilities and New York City Department of Environmental Protection.

We present an integrated hydrology/water operations simulation model of the Tuolumne and Merced River Basins, California, using the Water Evaluation and Planning (WEAP) platform. The model represents hydrology as well as water operations, which together influence water supplied for agricultural, urban, and environmental uses. The model is developed for impacts assessment using scenarios for climate change and other drivers of water system behavior. In this paper, we describe the model structure, its representation of historical streamflow, agricultural and urban water demands, and water operations. We describe projected impacts of climate change on hydrology and water supply to the major irrigation districts in the area, using uniform 2 °C, 4 °C, and 6 °C increases applied to climate inputs from the calibration period. Consistent with other studies, we find that the timing of hydrology shifts earlier in the water year in response to temperature warming (5-21 days). The integrated agricultural model responds with increased water demands 2 °C (1.4-2.0%), 4 °C (2.8-3.9%), and 6 °C (4.2-5.8%). In this sensitivity analysis, the combination of altered hydrology and increased demands results in decreased reliability of surface water supplied for agricultural purposes, with modeled quantity-based reliability metrics decreasing from a range of 0.84-0.90 under historical conditions to 0.75-0.79 under 6 °C warming scenario.

This paper presents a model of Andean glacier hydrology which can be used to assess the water management implications of possible future glacier retreat. The approach taken uses the Water Evaluation and Planning (WEAP) system and integrates both hydrologic processes and representations of the operations of built infrastructure. The model is applied in the Rio Santa watershed in Peru to illustrate how alternative water management strategies can be simulated. The WEAP platform built for this study has been used to engage with local stakeholders for water management.

Original abstract: For the past 30 years, a process of glacier retreat has been observed in the Andes, raising alarm among regional water resources managers. The purpose of this paper is to develop a model of the role of Andean glaciers in the hydrology of their associated watersheds, which is appropriate for application at a river basin scale, with an eye towards creating an analytical tool that can be used to assess the water management implications of possible future glacier retreat. While the paper delves deeply into our formulation of a glacier module within a water resources management modelling system, the widely subscribed Water Evaluation and Planning System (WEAP), the originality of our work lies less in the domain of glaciology and more in how we apply an existing reduced form representation of glacier evolution within a model of the climate-glacier-hydrology-water management continuum. Key insights gained pertain to appropriate ways to deploy these reduced form representations in a relatively data poor environment and to effectively integrate them into a modelling framework that places glaciers within a wider water management context. The study area is the Rio Santa watershed in Peru which contains many of the expansive glaciers of the singular Cordillera Blanca. The specific objectives of this study included: (i) adequately simulating both monitored glacier retreat and observed river flows from the last forty years using historical climate time series as model input; (ii) quantifying the proportion of river flow in the Rio Santa produced from melting glaciers during this period; (iii) estimating the historical contribution of groundwater accretions to river flows; and (vi) reproducing a reasonable simulation of recent hydropower operations in the Rio Santa system. In pursuit objective (i), a split sample calibration-validation of the model was conducted by comparing the simulated glacier area to Landsat images taken in 1987 and 1998 and observed and simulated river flow at 16 control points in the Rio Santa watershed. At the global scale of the watershed, the glacier retreat is correctly simulated for the period 1970/1999 with a calculated retreat equals to -23% when the observed retreat is of -24%. Having established that the model can respond to these scientific objectives, the ultimate goal of the study was to demonstrate how this integrated modelling system can be used as a decision support tool to assist in planning water management adaptation to climate change. This sort of integrated assessment is required to adapt water resources management in the Andes to a~range of future climatic conditions, improving the resilience of developing Andean economies such Peru's in the face of a major drive of global change. Artículo en acceso abierto Refiere que el proceso de retirada de glaciares en los Andes observado durante los últimos 30 años ha alarmado a los administradores regionales de recursos hídricos. El propósito de este documento es desarrollar un modelo del papel de los glaciares andinos en la hidrología de sus cuencas hidrográficas asociadas, que es apropiado para su aplicación a escala de cuenca, con miras a crear una herramienta analítica que pueda utilizarse para evaluar la Implicaciones de la gestión del agua de un posible futuro retiro de glaciares. Señala que el estudio profundiza en la formulación de un módulo glaciar dentro de un sistema de modelado de gestión de recursos hídricos, el Sistema de Evaluación y Planificación del Agua (WEAP) ampliamente suscrito, sin embargo, la originalidad del trabajo radica menos en cómo se aplica una representación de forma reducida existente de la evolución de los glaciares dentro de un modelo continuo de gestión de agua, hidrología y glaciares.

Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates in various parts of the world, especially in arid and semi-arid areas. Researchers and practitioners are increasingly calling for integrated approaches, and policy-makers are progressively supporting the inclusion of ecological and social aspects in water management programs. This paper contributes to this policy debate by providing an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. This modeling integration includes a risk-based economic optimization model and a hydrologic water management simulation model that have been specified for the Middle Guadiana basin, a vulnerable drought-prone agro-ecological area with highly regulated river systems in southwest Spain. Namely, two key water policy interventions were investigated: the implementation of minimum environmental flows (supported by the European Water Framework Directive, EU WFD), and a reduction in the legal amount of water delivered for irrigation (planned measure included in the new Guadiana River Basin Management Plan, GRBMP, still under discussion). Results indicate that current patterns of excessive water use for irrigation in the basin may put environmental flow demands at risk, jeopardizing the WFD's goal of restoring the ‘good ecological status’ of water bodies by 2015. Conflicts between environmental and agricultural water uses will be stressed during prolonged dry episodes, and particularly in summer low-flow periods, when there is an important increase of crop irrigation water requirements. Securing minimum stream flows would entail a substantial reduction in irrigation water use for rice cultivation, which might affect the profitability and economic viability of small rice-growing farms located upstream in the river. The new GRBMP could contribute to balance competing water demands in the basin and to increase economic water productivity, but might not be sufficient to ensure the provision of environmental flows as required by the WFD. A thoroughly revision of the basin's water use concession system for irrigation seems to be needed in order to bring the GRBMP in line with the WFD objectives. Furthermore, the study illustrates that social, economic, institutional, and technological factors, in addition to bio-physical conditions, are important issues to be considered for designing and developing water management strategies. The research initiative presented in this paper demonstrates that hydro-economic models can explicitly integrate all these issues, constituting a valuable tool that could assist policy makers for implementing sustainable irrigation policies.

In the Peruvian Andes, water infiltration from tropical wetlands, called páramo, generates headwaters for downstream rivers. The hydrological processes of these wetlands are not well understood within the larger hydrological system, impeding efforts to mitigate the rapid environmental changes anticipated due to regional population growth and climate change. This study constructed and calibrated a Water Evaluation and Planning (WEAP) system model for ecosystems with sparse data in the Quiroz-Chipillico watershed in the Piura region of Peru. The model simulates the impacts of possible changes within the hydrological system to assist decision-makers in strategizing about sustainable development for the region, especially the páramo. Using scenarios designed with stakeholder participation, the WEAP model for the Quiroz-Chipillico watershed examines river headflow production, reservoir water levels, and demand coverage for downstream users when the upstream páramo and its environs are subjected to changes of temperature, precipitation, and land use. The model reveals that while temperature and precipitation changes can be expected to impact páramo water production, the anticipated land use changes will be a primary driver of hydrological responses in the páramo and subsequent changes downstream.

Infiltration along a set of surge irrigated and a set of continuously irrigated furrows was studied using field data collected from 49 pairs of neutron probe access tubes and blocked furrow infiltrometers for each irrigation method. Surge irrigation reduced the average water application depth and the infiltration variability. A surge infiltration model based on proportional reductions in infiltration rate between surges was developed. Final field infiltration under surge irrigation was predicted for Yolo clay loam based on proportional reductions of the initial dry soil infiltration function. These results were compared with surge infiltration models suggested in the literature.