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

Image

Robust decision-making under uncertainty for a moorland ecosystem's water resources management under scenarios of climate variability

Presented at the American Geophysical Union Fall Meeting, 9-13 December 2013

Author(s): Flores, F. ; Forni, L. ; Escobar, M. ; Purkey, D.
Year: 2013

Research Area(s): Water Resources

Description: This study focuses on modeling the moorland ecosystem's water resources management under climate variability, and strengthening the capacities of local actors through a robust decision-making under uncertainty framework to analyze and plan water resources use in the region of Piura, Peru. The objective is to determine the reliability of the moorland ecosystem's water supply and to provide relevant hydrological information under scenarios of climate variability and other non-climate uncertainties. As a first step, a participatory workshop was carried out to identify the uncertainties that define availability of water resources, the potential strategies for adaptation to improve existing conditions, and the performance indicators by which to assess these uncertainties and strategies, using the XLRM assessment framework (eXogenous uncertainties, policy Levers, Relationships, and Measures). This study also used the WEAP (Water Evaluation And Planning system) platform to support water resources planning and decision-making under uncertainty e.g. climate change and other stresses in the system. The model includes the results of the XLRM framework and seeks to determine the importance that the moorlands have on the regional water system.
More information
External Link


Image

Integrated assessment of policy interventions for promoting sustainable irrigation in semi-arid environments: A hydro-economic modeling approach

Journal of Environmental Management 128, 144-160

Author(s): Blanco-Gutierrez, I. ; Purkey, D. ; Varela-Ortega, C.
Year: 2013

Research Area(s): Water Resources

Description: This paper describes the development of a hydro-economic modeling framework that links a farm-based economic model and a semi-distributed hydrologic model, and its application to a semi-arid river basin in Spain. Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates, especially in arid and semi-arid areas. There is a growing interest in integrated approaches that include ecological and social aspects in water management programs. This paper describes an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. It 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.
External Link


Image

Using economic and other performance measures to evaluate a municipal drought plan

Water Policy, in press, published online July 2013

Author(s): Yates, D. ; Purkey, D. ; Sieber, J. ; Vasquez Lavin, F.; Guerrero, S.; Hanemann, M.
Year: 2013

Research Area(s): Water Resources

Description: 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 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.
More information
External Link


Image

Scenario-based water resources planning for utilities in the Lake Victoria region

Physics and Chemistry of the Earth, Parts A/B/C, in press; available online 16 March 2013

Author(s): Mehta, V. ; Purkey, D. ; Aslam, O.; Dale, L.; Miller, N.
Year: 2013

Research Area(s): Water Resources

Description: This article describes the development of water resources models for three East African towns to investigate climate, infrastructure and demographic scenarios. Urban areas in the Lake Victoria 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. land-use 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 Lake Victoria region: Bukoba (Tanzania), Masaka (Uganda), and Kisii (Kenya).
More information
External Link


Image

Irrigation demand and supply, given projections of climate and land-use change, in Yolo County, California

Agricultural Water Management 117, 70-82

Author(s): Mehta, V. ; Joyce, B. ; Purkey, D. ; Haden, V.R.; Jackson, L.E.
Year: 2013

Research Area(s): Water Resources

Description: This article assesses the potential effects of climate change and adaptive management on irrigation water supply in the Cache Creek watershed in California. The authors built a model using the Water Evaluation And Planning (WEAP) system, and calibrated it using historical data (1971-2000) on streamflow, irrigation deliveries, and reservoir operations. Results show irrigation demand increasing by 26% and 32% under B1 and A2 baseline climate scenarios respectively in the latter part of the century. Increases in demand from climate change alone exceed applied water reductions 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.
More information
External Link