Climate change, water supply limits, and continued population growth have intensified the search for measures to conserve water in irrigated agriculture, the world's largest water user. Policy measures that encourage adoption of water-conserving irrigation technologies are widely believed to make more water available for cities and the environment. However, little integrated analysis has been conducted to test this hypothesis. This article presents results of an integrated basin-scale analysis linking biophysical, hydrologic, agronomic, economic, policy, and institutional dimensions of the Upper Rio Grande Basin of North America. It analyzes a series of water conservation policies for their effect on water used in irrigation and on water conserved. In contrast to widely-held beliefs, our results show that water conservation subsidies are unlikely to reduce water use under conditions that occur in many river basins. Adoption of more efficient irrigation technologies reduces valuable return flows and limits aquifer recharge. Policies aimed at reducing water applications can actually increase water depletions. Achieving real water savings requires designing institutional, technical, and accounting measures that accurately track and economically reward reduced water depletions. Conservation programs that target reduced water diversions or applications provide no guarantee of saving water.

Climate change and recurrent drought in many of the world's dry places continue to inspire the search for economically attractive measures to conserve water. This study analyzes water conservation practices in irrigated agriculture in a sub-basin in North America's Rio Grande. A method is developed to estimate water savings in irrigated agriculture that result from public subsidies to farmers who convert from surface to drip irrigation. The method accounts for economic incentives affecting farmers' choices on irrigation technology, crop mix, water application, and water depletion. Findings show that farmers will invest in technologies that reduce water applications when faced with lower financial costs for converting to drip irrigation. Subsidies for drip irrigation increase farm income, raise the value of food production, and reduce the amount of water applied to crops. However, an unexpected result is that water conservation subsidies that promote conversion to drip irrigation can increase the demand for water depleted by crops. Our findings show that where water rights exist, water rights administrators will need to guard against increased depletion of the water source in the face of growing subsidies for drip irrigation. Our approach for analyzing water conservation programmes can be applied where water is scarce, irrigation is significant, food security is important, and water conservation policies are under debate.

In the Rio Grande Basin of North America, water is overappropriated and demand for water grows while supplies are constrained by drought and climate change. The Basin is currently in its seventh year of drought, and reservoirs are at historically low levels. Thus agricultural and municipal river diversions have been sharply curtailed, and low flows threaten endangered species. A central policy challenge is the design and implementation of plans that efficiently and fairly allocate the Basin’s water supplies. Such plans are complicated by the demands of existing water users, potential new users, three state governments, and two sovereign nations. To address these issues, an integrated basinwide nonlinear programming model was designed and constructed for the purpose of optimizing water allocations and use levels for the Basin. The model tests whether institutional adjustments can limit damages caused by drought and identifies changes in water uses and allocations that result from those adjustments. Compare...

Many of the world's irrigated regions face the problem of aging infrastructure and declining revenues to maintain and repair irrigation structures. Policy debates over climate change, population growth, food security, and impacts of irrigation on ecological assets compound the problem, raising the urgency to invest in irrigation infrastructure. Meanwhile, a global call for full-cost recovery for water infrastructure investments increases the need to identify the economic value of sustaining irrigation infrastructure. Despite the growing debates, little comprehensive research has been conducted summarizing factors affecting irrigation investments or policy options available for sustaining irrigation infrastructure. This paper reviews research on factors affecting the level and value of irrigation infrastructure investments. It also reviews research on policy instruments for sustaining irrigation infrastructure, considering both market and institutional approaches. Several market approaches have been found to have the potential to influence the economic attractiveness of investments in irrigation infrastructure. These include infrastructure subsidies, clearing titles to water rights, marginal cost pricing, and non-volumetric pricing. Institutional approaches described include regulatory measures, transboundary agreements, and water user associations. Results may contribute to current debates in various regional, national, and international forums on whether and how water should be priced for agricultural use.