David Purkey
Senior Scientist
Davis, CA
dpurkey@sei-us.org
skype: dpurkey
+1 (530) 753-3035 x1#
David Purkey runs the Northern California office of SEI-US and is actively involved in the SEI Water and Sanitation Program in the the United States and globally. Much of his work centers around the development, dissemination and application of SEI's Water Evaluation and Planning (WEAP) system. His research interests include understanding the potential impacts of and adaptation to climate change in the water sector and aquatic ecosystems, integrated water resources management that focuses on linking the management of surface water and groundwater to meet a broad spectrum of objectives, and equitable management of transboundary water resources. David and his team are experienced in applying a range of hydrologic, hydraulic, and planning models in setting as diversion as California, the US-Mexico border, the Great Lakes, and West and Southern Africa. David received his Ph.D. in hydrology from the University of California, Davis in 1998.
Recent Publications by David Purkey
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Modifying agricultural water management to adapt to climate change in California's central valleyClimatic Change 109 (Supplement 1), 299-316; Special Issue: California Second Assessment: New Climate Change Impact Studies and Implications for Adaptation Author(s): Joyce, B. ; Mehta, V. ; Purkey, D. ; Dale, L.L.; Hanemann, M.Year: 2011 Research Area(s): Water Resources Description: 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. The authors 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. 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. 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.External Link |
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Water Management Adaptations to Prevent Loss of Spring-Run Chinook Salmon in California under Climate ChangeJournal of Water Resources Planning and Management, published online ahead of print Author(s): Thompson, L.C. ; Escobar, M. ; Purkey, D. ; Yates, D. ; Mosser, C.M.; Moyle, P.B.Year: 2011 Research Area(s): Water Resources Description: Spring-run Chinook salmon (Oncorhynchus tshawytscha) are particularly vulnerable to climate change because adults over-summer in freshwater streams before spawning in autumn. In this study, the authors 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. For all climate scenarios and model combinations, the model found increased adult summer thermal mortality and population declines. Of management adaptations tested, only ceasing water diversion for power production from the summer holding reach resulted in cooler water temperatures, more adults surviving to spawn, and extended population survival time, albeit with a significant loss of power production.More information External Link |
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Integrated economic-hydrologic analysis of policy responses to promote sustainable water use under changing climatic conditionsPresented at the European Association of Agricultural Economists (EAAE) 2011 Congress, Zurich, Switzerland, Aug. 30-Sept. 2, 2011 Author(s): Blanco-Gutié ; Purkey, D. ; rrez, I.; Varela-Ortega, C.Year: 2011 Research Area(s): Water Resources Description: This study analyzes the effects of national and European water policies in Spain under normal and dry climate conditions, using a novel hydro-economic model based on the integration of a multiscale economic optimization model and a hydrology water management simulation model built in WEAP. Application of the model was carried out in the Middle Guadiana basin, a surface-irrigated area of about 29,000 km2 in the southwestern Iberian Peninsula. Balancing the trade-offs between agricultural production and nature conservation is one of the major tasks that face policymakers in Spain, and especially in the Guadiana Basin. This paper contributes to the debate by providing an integrated economic-hydrologic modeling framework that captures the dynamics and outcomes of human-hydrological interactions, from farm-level to river-basin levels.More information Download PDF |
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Potential impacts on hydrology and hydropower production under climate warming of the Sierra NevadaJournal of Water and Climate Change 2:1, 29-43 Author(s): Mehta, V. ; Yates, D. ; Purkey, D. ; Young, C. ; Rheinheimer, D.E.; Viers, J.H.; Mount, J.F.Year: 2011 Research Area(s): Water Resources ; Energy Modeling Description: Watersheds of the Cosumnes, American, Bear and Yuba (CABY) rivers in the Sierra Nevada, Calif., 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.External Link |
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Modelling the hydrologic role of glaciers within a Water Evaluation and Planning System (WEAP): A case study in the Rio Santa watershed (Peru)Hydrology and Earth System Sciences Discussions 8:1, 869-916 Author(s): Condom, T. ; Escobar, M. ; Purkey, D. ; Pouget, J.C.; Suarez, W.; Ramos, C.; Apaestegui, J.; Zapata, M.; Gomez, J.; Vergara, W.Year: 2011 Research Area(s): Water Resources Description: Glaciers are retreating in the Andes, raising alarm among regional water resources managers. Building on the Water Evaluation and Planning System (WEAP), the authors modeled the glaciers' role in associated watersheds, aiming to create an analytical tool to assess the implications of possible future glacier retreat on water management. The study area is the Rio Santa watershed in Peru, which contains many of the glaciers of the Cordillera Blanca.More information External Link |