Water claims in many of the world's arid basins exceed reliable supplies. Water demands for irrigation, urban use, the environment, and energy continue to grow, while supplies remain constrained by unsustainable use, drought and impacts of climate change. For example, policymakers in North America's Upper Rio Grande Basin face the challenge of designing plans for allocating the basin's water supplies efficiently and fairly to support current uses and current environments. Managers also seek resilient institutions that can ensure adequate supplies for future generations. This paper addresses those challenges by designing and applying an integrated basin-scale framework that accounts for the basin's most important hydrologic, economic, and institutional constraints. Its unique contribution is a quantitative analysis of three policies for addressing long term goals for the basin's reservoirs and aquifers: (1) no sustainability for water stocks, (2) sustaining water stocks, and (3) renewing water stocks. It identifies water use and allocation trajectories over time that result from each of these three plans. Findings show that it is hydrologically and institutionally feasible to manage the basin's water supplies sustainably. The economic cost of protecting the sustainability of the basin's water stocks can be achieved at 6 -11 percent of the basin's average annual total economic value of water over a 20 year time horizon . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 Economic Costs of Sustaining Water Supplies: Findings from the Rio Grande
BackgroundTwenty-first century decision-makers face an array of challenges in the search for sustainable environmental policies. In most river basins, actions taken for one use, at one place, or in one period affect water quantity or quality for another use, at another location, or in another period. For this reason there is considerable need for integrated water resources management (IWRM) plans that couple the physics governing water stocks and flows with economic and institutional factors affecting water's demands and supplies. Decision makers need integrated plans that help them identify the full range of current and future consequences associated with various management strategies and growing resource demands in the face of current or altered climate. A water manager may need access to an integrated framework to evaluate effects of drought on water supply as well as its impacts on other systems such as key ecological assets, agriculture, urban water use, and economic development.Effectively managing complex water systems for the benefit of current and future generations is an ongoing challenge facing contemporary water managers. A single, integrated basin-scale plan presents several advantages for managers, farmers, and the water-using public in the search for be...