In 2009 California was in the third year of severe drought, and legal rulings had further limited... more In 2009 California was in the third year of severe drought, and legal rulings had further limited water deliveries to agriculture in the San Joaquin Valley. Water users, farmers, and policymakers were interested in the effects of drought and additional water restrictions. Using data from state agencies, we forecasted the changes in agricultural production, revenue, and jobs due to water shortage in the San Joaquin Valley.
In arid regions, including Australia's Murray-Darling basin and California's Central Vall... more In arid regions, including Australia's Murray-Darling basin and California's Central Valley, increasing salinity is a problem affecting agriculture, regional economies, urban areas, and the environment. The direct costs of salinity to agriculture in the Murray-Darling basin and California's Central Valley are on the order of $500 million per year. Policymakers want to design policies to effectively manage salinity and, as such, need to understand how farmers respond to changing salinity levels. Reduced crop yields account for the largest direct cost of salinity to agriculture however farmers are able to mitigate effects through field management. Consequently, there is a difference between experimentally estimated yield-salinity functions and those which result from farmer behavioral response to salinity. The latter are relevant for salinity policy analysis and, to our knowledge, have not previously been estimated in the literature. We model farmers as profit-maximizing c...
The impacts of climate change in arid areas will be mostly driven by changes in water scarcity. W... more The impacts of climate change in arid areas will be mostly driven by changes in water scarcity. While regional rainfall changes are uncertain, the increase in temperature is forecast with much more confidence; temperature change is a strong driving force behind forecast reductions in irrigation water supplies. Even with relatively unchanged average rainfall, changes in the timing of precipitation will cause supply shortages. Climate Change and Agriculture Take the case of California as an example of the likely effect of climate change on agriculture in an arid region with a postindustrial economy. California agriculture is heavily dependent on irrigation so it may offer lessons for adaptation to climate change that can be applied to irrigated agriculture in other arid regions. Climate change will have negative effects on California's irrigated agriculture in terms of increased water scarcity, more variation in water supply, and lower yields due to heat stress. Parallel changes in technology and markets will partially or totally offset the negative effects. Technological advances such as fertilizers, disease resistant crops, and mechanical improvements have increased crop yields in California by an average of 1.4% per year (Brunke, Sumner, and Howitt, 2004). While increased yields will help dampen the negative effect of a warm-dry climate, continued growth of 1.4% per year is likely not sustainable and is expected to level off in the future (Alston and Pardey, 2009). Even so, technological change will offset climate related yield reductions for some California crops.
Water will drive California response to climate change alifornia's agricultural C industry has a ... more Water will drive California response to climate change alifornia's agricultural C industry has a comparative advantage in its climate and water supplies However, global climate change may slowly change both of these foundations
Sea level rise, large-scale flooding, and new conveyance arrangements for water exports may incre... more Sea level rise, large-scale flooding, and new conveyance arrangements for water exports may increase future water salinity for local agricultural production in California's Sacramento-San Joaquin Delta. Increasing salinity in crop root zones often decreases crop yields and crop revenues. Salinity effects are nonlinear, and vary with crop choice and other factors including drainage and residence time of irrigation water. Here, we explore changes in agricultural production in the Delta under various combinations of water management, large-scale flooding, and future sea level rise. Water management alternatives include through-Delta water exports (current conditions), dual conveyance (through-Delta and a 6,700 Mm 3 yr-1 [or 7500 cfs] capacity peripheral canal or tunnel) and the flooding of five western islands with and without peripheral exports. We employ results from previous hydrodynamic simulations of likely changes in salinity for irrigation water at points in the Delta. We connect these irrigation water salinity values into a detailed agro-economic model of Delta agriculture to estimate local crop yield
A regional hydroeconomic model is developed to include demand shifts from nonprice water conserva... more A regional hydroeconomic model is developed to include demand shifts from nonprice water conservation programs as input parameters and decision variables. Stochastic nonlinear programming then jointly identifies the benefit-maximizing portfolio of conservation and leak reduction programs, infrastructure expansions, and operational allocations under variable water availability. We present a detailed application for 12 governorates in the Hashemite Kingdom of Jordan. It considers targeted installations of water-efficient appliances, leak reduction in the distribution system, surface and groundwater development, seawater desalination, conveyance, and wastewater treatment projects. Results show that (1) water conservation by urban users generates substantial regional benefits and can delay infrastructure expansions; (2) some rationing and conjunctive use operations smooth operations during droughts; (3) a broad mix of source developments, conveyance expansions, and leak reduction programs can forestall the need for desalination; (4) the Disi carrier to Amman should include a large branch to Karak; and (5) increasing conveyance from Ma'an, Irbid, and Mafraq can avert impending crises in the neighboring districts of Tafelah, Ajloun, and Zarqa.
Once a landscape has been established, its origins are repressed from memory. It takes on the app... more Once a landscape has been established, its origins are repressed from memory. It takes on the appearance of an 'object' which has been there, outside us, from the start." Karatani Kojin (1993), Origins of Japanese Literature vi simultaneously. California needs to develop a strategic direction for the Delta before working out all the details of how to get there.
The Sacramento-San Joaquin Delta consists of some 737,000 acres of low-lying lands and channels a... more The Sacramento-San Joaquin Delta consists of some 737,000 acres of low-lying lands and channels at the confluence of the Sacramento and San Joaquin Rivers (Figure S1). This region lies at the very heart of California's water policy debates, transporting vast flows of water from northern and eastern California to farming and population centers in the western and southern parts of the state. This critical water supply system is threatened by the likelihood that a large earthquake or other natural disaster could inflict catastrophic damage on its fragile levees, sending salt water toward the pumps at its southern edge. In another area of concern, water exports are currently under restriction while regulators and the courts seek to improve conditions for imperiled native fish. Leading policy proposals to address these issues include improvements in land and water management to benefit native species, and the development of a "dual conveyance" system for water exports, in which a new seismically resistant canal or tunnel would convey a portion of water supplies under or around the Delta instead of through the Delta's channels. This focus on the Delta has caused considerable concern within the Delta itself, where residents and local governments have worried that changes in water supply and environmental management could harm the region's economy and residents. In 2009, the state laid out a new policy framework and governance structure for the Delta. The Delta Reform Act (Senate Bill X7-1) declared it a state priority to address two "co-equal goals"-improving water supply reliability and protecting and enhancing the Delta ecosystem-while also protecting and enhancing the "unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place " (Water Code § 85054). The Delta will indeed be evolving, as a result of both reform efforts seeking to address these co-equal goals and also irreversible natural forces (earthquakes, flood flows, sea level rise, climate warming) that threaten the stability of Delta levees and alter water quality. This study examines the potential economic effects of changes in the Delta land and waterscape as a result of management activities and natural forces and suggests planning priorities to support transitions in the Delta economy. We review recent patterns and trends in Delta land use and employment, and we draw on a range of data and modeling tools to assess the effects of several types of physical changes on economic activity in the Delta: (i) the permanent flooding of roughly 75,000 acres of land on subsided Delta islands that may not offer sufficient economic justification for repair after flooding; (ii) increases in irrigation water salinity from the introduction of dual conveyance, sea level rise, and the flooding of islands that restrict salinity intrusion from the Delta's western edge; and (iii) reductions in cropland from the expansion of seasonal floodplain and tidal marsh habitat. Most of these changes will directly affect land and water conditions in the Delta's primary zone-nearly 500,000 acres of largely subsided agricultural lands in the inner Delta, where development is restricted because of high flood risk. Within the first half of this century, island flooding, habitat conversions, the
Farmers make joint water and land use decisions for economic purposes based in part on water avai... more Farmers make joint water and land use decisions for economic purposes based in part on water availability and reliability. A two‐stage economic production model is developed to examine the effects of hydrologic uncertainty and water prices on agricultural production, cropping patterns, and water and irrigation technology use. The model maximizes net expected farm profit from permanent and annual crop production with probabilistic water availability and a variety of irrigation technologies. Results demonstrate effects of water availability, price, and reliability on economic performance, annual and long‐run cropping patterns, and irrigation technology decisions. Variations in water price and availability affect the desirability of different irrigation technologies. Increased water supply reliability can raise the probability of higher economic returns and promote more effective use of water for permanent crops. Such economic benefits can be compared to costs of operational changes an...
Journal of Water Resources Planning and Management, 2010
This paper applies two-stage stochastic quadratic programming to optimize conjunctive use operati... more This paper applies two-stage stochastic quadratic programming to optimize conjunctive use operations of groundwater pumping and artificial recharge with farmer's expected revenue and cropping decisions. The two-stage programming approach allows modeling of water and permanent crop production decisions, with recourse for uncertain conditions of hydrology, annual crops, and irrigation technology decisions. Results indicate potential gains in expected net benefits and reduction in income variability from conjunctive use, with increase in high value permanent crops along with more efficient irrigation technology.
Journal of Water Resources Planning and Management, 2002
Most of all-thanks to Bob and Joan Burton, my beloved parents. Thank you for the help and guidanc... more Most of all-thanks to Bob and Joan Burton, my beloved parents. Thank you for the help and guidance you've given me while at Davis and every day prior.
Journal of Water Resources Planning and Management, 2007
This paper employs an economic-engineering optimization model to explore water supply options for... more This paper employs an economic-engineering optimization model to explore water supply options for environmental restoration of the Colorado River Delta, Mexico. Potential water sources include reductions in local agricultural and urban water use through water markets, wastewater reuse, and additional Colorado River flows from the United States. For these alternatives, the optimization model estimates operating and water scarcity costs, water scarcity volumes, and marginal economic costs of environmental flows and values of additional Colorado River flows from the United States over a range of required delta environmental flows. Economic values for agricultural and urban water uses were estimated by two ancillary models. The results provide insights into economically promising water supplies for restoration activities. Quantifying the trade-off between agricultural and urban economic valuation and environmental flows provides a framework for decision-makers to quantify their valuation of environmental flows. The model also provides a framework for integrating additional knowledge of the system as information becomes available.
Journal of Water Resources Planning and Management, 2006
This paper develops and applies an economically driven simulation model for California's Friant-K... more This paper develops and applies an economically driven simulation model for California's Friant-Kern system, a region characterized by diverse water sources employed predominantly for commercial irrigated agriculture, with significant local water trading activity. The economic-engineering simulation approach highlights the importance of representing user economic decisions for water systems in a context of complex physical and infrastructure systems dominated by economic water uses. The model simulates how water users conserve, select supplies and make water exchange and market decisions in response to water costs and availability, and provides estimates of economic and operational impacts of alternative policies for the Friant-Kern system. Results show that high surface water prices cause farmers to pump more groundwater, disturbing an existing conjunctive use system and aggravating regional groundwater overdraft.
Future water management will shift from building new water supply systems to better operating exi... more Future water management will shift from building new water supply systems to better operating existing ones. The variation of water values in time and space will increasingly motivate efforts to address water scarcity and reduce water conflicts. Hydro-economic models represent spatially distributed water resource systems, infrastructure, management options and economic values in an integrated manner. In these tools water allocations and management are either driven by the economic value of water or economically evaluated to provide policy insights and reveal opportunities for better management. A central concept is that water demands are not fixed requirements but rather functions where quantities of water use at different times have varying total and marginal economic values. This paper reviews techniques to characterize the economic value of water use and include such values in mathematical models. We identify the key steps in model design and diverse problems, formulations, levels of integration, spatial and temporal scales, and solution techniques addressed and used by over 80 hydro-economic modeling efforts dating back 45-years from 23 countries. We list current limitations of the approach, suggest directions for future work, and recommend ways to improve policy relevance.
This paper uses simple hydro-economic optimization to investigate a wide range of regional water ... more This paper uses simple hydro-economic optimization to investigate a wide range of regional water system management options for northern Baja California, Mexico. Hydro-economic optimization models, even with parsimonious model formulations, enable investigation of promising water management portfolios for supplying water to agricultural, environmental and urban users. CALVIN, a generalized hydro-economic model, is used in a case study of Baja California. This drought-prone region faces significant challenges to supply water to agriculture and its fast growing border cities. Water management portfolios include water markets, wastewater reuse, seawater desalination and infrastructure expansions. Water markets provide the flexibility to meet future urban demands; however conveyance capacity limits their use. Wastewater reuse and conveyance expansions are economically promising. At current costs desalination is currently uneconomical for Baja California compared to other alternatives. Even simple hydro-economic models suggest ways to increase efficiency of water management in water scarce areas, and provide an economic basis for evaluating long-term water management solutions.
This paper describes calibration methods for models of agricultural production and water use in w... more This paper describes calibration methods for models of agricultural production and water use in which economic variables can directly interact with hydrologic network models or other biophysical system models. We also describe and demonstrate the use of systematic calibration checks at different stages for efficient debugging of models. The central model is the California Statewide Agricultural Production Model (SWAP), a Positive Mathematical Programming (PMP) model of California irrigated agriculture. We outline the six step calibration procedure and demonstrate the model with an empirical policy analysis. Two new techniques are included compared with most previous PMP-based models: exponential PMP cost functions and Constant Elasticity of Substitution (CES) regional production functions. We then demonstrate the use of this type of disaggregated production model for policy analysis by evaluating potential water transfers under drought conditions. The analysis links regional production functions with a water supply network. The results show that a more flexible water market allocation can reduce revenue losses from drought up to 30%. These results highlight the potential of self-calibrated models in policy analysis. While the empirical application is for a California agricultural and environmental water system, the approach is general and applicable to many other situations and locations.
In 2009 California was in the third year of severe drought, and legal rulings had further limited... more In 2009 California was in the third year of severe drought, and legal rulings had further limited water deliveries to agriculture in the San Joaquin Valley. Water users, farmers, and policymakers were interested in the effects of drought and additional water restrictions. Using data from state agencies, we forecasted the changes in agricultural production, revenue, and jobs due to water shortage in the San Joaquin Valley.
In arid regions, including Australia's Murray-Darling basin and California's Central Vall... more In arid regions, including Australia's Murray-Darling basin and California's Central Valley, increasing salinity is a problem affecting agriculture, regional economies, urban areas, and the environment. The direct costs of salinity to agriculture in the Murray-Darling basin and California's Central Valley are on the order of $500 million per year. Policymakers want to design policies to effectively manage salinity and, as such, need to understand how farmers respond to changing salinity levels. Reduced crop yields account for the largest direct cost of salinity to agriculture however farmers are able to mitigate effects through field management. Consequently, there is a difference between experimentally estimated yield-salinity functions and those which result from farmer behavioral response to salinity. The latter are relevant for salinity policy analysis and, to our knowledge, have not previously been estimated in the literature. We model farmers as profit-maximizing c...
The impacts of climate change in arid areas will be mostly driven by changes in water scarcity. W... more The impacts of climate change in arid areas will be mostly driven by changes in water scarcity. While regional rainfall changes are uncertain, the increase in temperature is forecast with much more confidence; temperature change is a strong driving force behind forecast reductions in irrigation water supplies. Even with relatively unchanged average rainfall, changes in the timing of precipitation will cause supply shortages. Climate Change and Agriculture Take the case of California as an example of the likely effect of climate change on agriculture in an arid region with a postindustrial economy. California agriculture is heavily dependent on irrigation so it may offer lessons for adaptation to climate change that can be applied to irrigated agriculture in other arid regions. Climate change will have negative effects on California's irrigated agriculture in terms of increased water scarcity, more variation in water supply, and lower yields due to heat stress. Parallel changes in technology and markets will partially or totally offset the negative effects. Technological advances such as fertilizers, disease resistant crops, and mechanical improvements have increased crop yields in California by an average of 1.4% per year (Brunke, Sumner, and Howitt, 2004). While increased yields will help dampen the negative effect of a warm-dry climate, continued growth of 1.4% per year is likely not sustainable and is expected to level off in the future (Alston and Pardey, 2009). Even so, technological change will offset climate related yield reductions for some California crops.
Water will drive California response to climate change alifornia's agricultural C industry has a ... more Water will drive California response to climate change alifornia's agricultural C industry has a comparative advantage in its climate and water supplies However, global climate change may slowly change both of these foundations
Sea level rise, large-scale flooding, and new conveyance arrangements for water exports may incre... more Sea level rise, large-scale flooding, and new conveyance arrangements for water exports may increase future water salinity for local agricultural production in California's Sacramento-San Joaquin Delta. Increasing salinity in crop root zones often decreases crop yields and crop revenues. Salinity effects are nonlinear, and vary with crop choice and other factors including drainage and residence time of irrigation water. Here, we explore changes in agricultural production in the Delta under various combinations of water management, large-scale flooding, and future sea level rise. Water management alternatives include through-Delta water exports (current conditions), dual conveyance (through-Delta and a 6,700 Mm 3 yr-1 [or 7500 cfs] capacity peripheral canal or tunnel) and the flooding of five western islands with and without peripheral exports. We employ results from previous hydrodynamic simulations of likely changes in salinity for irrigation water at points in the Delta. We connect these irrigation water salinity values into a detailed agro-economic model of Delta agriculture to estimate local crop yield
A regional hydroeconomic model is developed to include demand shifts from nonprice water conserva... more A regional hydroeconomic model is developed to include demand shifts from nonprice water conservation programs as input parameters and decision variables. Stochastic nonlinear programming then jointly identifies the benefit-maximizing portfolio of conservation and leak reduction programs, infrastructure expansions, and operational allocations under variable water availability. We present a detailed application for 12 governorates in the Hashemite Kingdom of Jordan. It considers targeted installations of water-efficient appliances, leak reduction in the distribution system, surface and groundwater development, seawater desalination, conveyance, and wastewater treatment projects. Results show that (1) water conservation by urban users generates substantial regional benefits and can delay infrastructure expansions; (2) some rationing and conjunctive use operations smooth operations during droughts; (3) a broad mix of source developments, conveyance expansions, and leak reduction programs can forestall the need for desalination; (4) the Disi carrier to Amman should include a large branch to Karak; and (5) increasing conveyance from Ma'an, Irbid, and Mafraq can avert impending crises in the neighboring districts of Tafelah, Ajloun, and Zarqa.
Once a landscape has been established, its origins are repressed from memory. It takes on the app... more Once a landscape has been established, its origins are repressed from memory. It takes on the appearance of an 'object' which has been there, outside us, from the start." Karatani Kojin (1993), Origins of Japanese Literature vi simultaneously. California needs to develop a strategic direction for the Delta before working out all the details of how to get there.
The Sacramento-San Joaquin Delta consists of some 737,000 acres of low-lying lands and channels a... more The Sacramento-San Joaquin Delta consists of some 737,000 acres of low-lying lands and channels at the confluence of the Sacramento and San Joaquin Rivers (Figure S1). This region lies at the very heart of California's water policy debates, transporting vast flows of water from northern and eastern California to farming and population centers in the western and southern parts of the state. This critical water supply system is threatened by the likelihood that a large earthquake or other natural disaster could inflict catastrophic damage on its fragile levees, sending salt water toward the pumps at its southern edge. In another area of concern, water exports are currently under restriction while regulators and the courts seek to improve conditions for imperiled native fish. Leading policy proposals to address these issues include improvements in land and water management to benefit native species, and the development of a "dual conveyance" system for water exports, in which a new seismically resistant canal or tunnel would convey a portion of water supplies under or around the Delta instead of through the Delta's channels. This focus on the Delta has caused considerable concern within the Delta itself, where residents and local governments have worried that changes in water supply and environmental management could harm the region's economy and residents. In 2009, the state laid out a new policy framework and governance structure for the Delta. The Delta Reform Act (Senate Bill X7-1) declared it a state priority to address two "co-equal goals"-improving water supply reliability and protecting and enhancing the Delta ecosystem-while also protecting and enhancing the "unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place " (Water Code § 85054). The Delta will indeed be evolving, as a result of both reform efforts seeking to address these co-equal goals and also irreversible natural forces (earthquakes, flood flows, sea level rise, climate warming) that threaten the stability of Delta levees and alter water quality. This study examines the potential economic effects of changes in the Delta land and waterscape as a result of management activities and natural forces and suggests planning priorities to support transitions in the Delta economy. We review recent patterns and trends in Delta land use and employment, and we draw on a range of data and modeling tools to assess the effects of several types of physical changes on economic activity in the Delta: (i) the permanent flooding of roughly 75,000 acres of land on subsided Delta islands that may not offer sufficient economic justification for repair after flooding; (ii) increases in irrigation water salinity from the introduction of dual conveyance, sea level rise, and the flooding of islands that restrict salinity intrusion from the Delta's western edge; and (iii) reductions in cropland from the expansion of seasonal floodplain and tidal marsh habitat. Most of these changes will directly affect land and water conditions in the Delta's primary zone-nearly 500,000 acres of largely subsided agricultural lands in the inner Delta, where development is restricted because of high flood risk. Within the first half of this century, island flooding, habitat conversions, the
Farmers make joint water and land use decisions for economic purposes based in part on water avai... more Farmers make joint water and land use decisions for economic purposes based in part on water availability and reliability. A two‐stage economic production model is developed to examine the effects of hydrologic uncertainty and water prices on agricultural production, cropping patterns, and water and irrigation technology use. The model maximizes net expected farm profit from permanent and annual crop production with probabilistic water availability and a variety of irrigation technologies. Results demonstrate effects of water availability, price, and reliability on economic performance, annual and long‐run cropping patterns, and irrigation technology decisions. Variations in water price and availability affect the desirability of different irrigation technologies. Increased water supply reliability can raise the probability of higher economic returns and promote more effective use of water for permanent crops. Such economic benefits can be compared to costs of operational changes an...
Journal of Water Resources Planning and Management, 2010
This paper applies two-stage stochastic quadratic programming to optimize conjunctive use operati... more This paper applies two-stage stochastic quadratic programming to optimize conjunctive use operations of groundwater pumping and artificial recharge with farmer's expected revenue and cropping decisions. The two-stage programming approach allows modeling of water and permanent crop production decisions, with recourse for uncertain conditions of hydrology, annual crops, and irrigation technology decisions. Results indicate potential gains in expected net benefits and reduction in income variability from conjunctive use, with increase in high value permanent crops along with more efficient irrigation technology.
Journal of Water Resources Planning and Management, 2002
Most of all-thanks to Bob and Joan Burton, my beloved parents. Thank you for the help and guidanc... more Most of all-thanks to Bob and Joan Burton, my beloved parents. Thank you for the help and guidance you've given me while at Davis and every day prior.
Journal of Water Resources Planning and Management, 2007
This paper employs an economic-engineering optimization model to explore water supply options for... more This paper employs an economic-engineering optimization model to explore water supply options for environmental restoration of the Colorado River Delta, Mexico. Potential water sources include reductions in local agricultural and urban water use through water markets, wastewater reuse, and additional Colorado River flows from the United States. For these alternatives, the optimization model estimates operating and water scarcity costs, water scarcity volumes, and marginal economic costs of environmental flows and values of additional Colorado River flows from the United States over a range of required delta environmental flows. Economic values for agricultural and urban water uses were estimated by two ancillary models. The results provide insights into economically promising water supplies for restoration activities. Quantifying the trade-off between agricultural and urban economic valuation and environmental flows provides a framework for decision-makers to quantify their valuation of environmental flows. The model also provides a framework for integrating additional knowledge of the system as information becomes available.
Journal of Water Resources Planning and Management, 2006
This paper develops and applies an economically driven simulation model for California's Friant-K... more This paper develops and applies an economically driven simulation model for California's Friant-Kern system, a region characterized by diverse water sources employed predominantly for commercial irrigated agriculture, with significant local water trading activity. The economic-engineering simulation approach highlights the importance of representing user economic decisions for water systems in a context of complex physical and infrastructure systems dominated by economic water uses. The model simulates how water users conserve, select supplies and make water exchange and market decisions in response to water costs and availability, and provides estimates of economic and operational impacts of alternative policies for the Friant-Kern system. Results show that high surface water prices cause farmers to pump more groundwater, disturbing an existing conjunctive use system and aggravating regional groundwater overdraft.
Future water management will shift from building new water supply systems to better operating exi... more Future water management will shift from building new water supply systems to better operating existing ones. The variation of water values in time and space will increasingly motivate efforts to address water scarcity and reduce water conflicts. Hydro-economic models represent spatially distributed water resource systems, infrastructure, management options and economic values in an integrated manner. In these tools water allocations and management are either driven by the economic value of water or economically evaluated to provide policy insights and reveal opportunities for better management. A central concept is that water demands are not fixed requirements but rather functions where quantities of water use at different times have varying total and marginal economic values. This paper reviews techniques to characterize the economic value of water use and include such values in mathematical models. We identify the key steps in model design and diverse problems, formulations, levels of integration, spatial and temporal scales, and solution techniques addressed and used by over 80 hydro-economic modeling efforts dating back 45-years from 23 countries. We list current limitations of the approach, suggest directions for future work, and recommend ways to improve policy relevance.
This paper uses simple hydro-economic optimization to investigate a wide range of regional water ... more This paper uses simple hydro-economic optimization to investigate a wide range of regional water system management options for northern Baja California, Mexico. Hydro-economic optimization models, even with parsimonious model formulations, enable investigation of promising water management portfolios for supplying water to agricultural, environmental and urban users. CALVIN, a generalized hydro-economic model, is used in a case study of Baja California. This drought-prone region faces significant challenges to supply water to agriculture and its fast growing border cities. Water management portfolios include water markets, wastewater reuse, seawater desalination and infrastructure expansions. Water markets provide the flexibility to meet future urban demands; however conveyance capacity limits their use. Wastewater reuse and conveyance expansions are economically promising. At current costs desalination is currently uneconomical for Baja California compared to other alternatives. Even simple hydro-economic models suggest ways to increase efficiency of water management in water scarce areas, and provide an economic basis for evaluating long-term water management solutions.
This paper describes calibration methods for models of agricultural production and water use in w... more This paper describes calibration methods for models of agricultural production and water use in which economic variables can directly interact with hydrologic network models or other biophysical system models. We also describe and demonstrate the use of systematic calibration checks at different stages for efficient debugging of models. The central model is the California Statewide Agricultural Production Model (SWAP), a Positive Mathematical Programming (PMP) model of California irrigated agriculture. We outline the six step calibration procedure and demonstrate the model with an empirical policy analysis. Two new techniques are included compared with most previous PMP-based models: exponential PMP cost functions and Constant Elasticity of Substitution (CES) regional production functions. We then demonstrate the use of this type of disaggregated production model for policy analysis by evaluating potential water transfers under drought conditions. The analysis links regional production functions with a water supply network. The results show that a more flexible water market allocation can reduce revenue losses from drought up to 30%. These results highlight the potential of self-calibrated models in policy analysis. While the empirical application is for a California agricultural and environmental water system, the approach is general and applicable to many other situations and locations.
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Papers by Richard Howitt