The Problem:

Water resources managers all over the rapidly growing southwestern U.S. (including in Arizona) are increasingly faced with over-stressed rivers and aquifers as climate varies, population and water demands grow, land-uses change, and new and competing water uses emerge. Decision makers are therefore faced with the problem of how to support sustainable development and, in particular, how to maintain sustainable water resources. Proper hydrologic decision-making and policy analysis requires that all available knowledge about the physical and behavioral aspects of the water resources system be brought to bear. A current regional drought (1999-ongoing) has raised new concerns about how to sustain the combination of agricultural, urban and in-stream uses of water that underlie the socio-economic and ecological structure in the region. Sustainability implies a balance of supply and demand throughout a basin, not just for the basin as a whole. Proper management with a view to sustainability requires accurate information about the complex interacting processes governing the hydrology of a region, including uncontrollable processes such as climate, and potentially controllable processes such as water storage in reservoirs and recharging aquifers. Sustainable water resource management also requires an understanding of how public policies regarding water pricing, water trading, and economic development influence water demand and transfers of water between different types of users. But there are significant gaps in our current knowledge of both the physical processes governing within-basin fluxes of water (including: i) the amount and variability of precipitation and evapotranspiration across the basin, ii) groundwater-surface water exchange, and iii) the partitioning of snowmelt and rain between runoff and infiltration, and then between evapotranspiration and recharge) and the impacts of public policies on water use and water demand. Given the strong physical linkages between these processes, and the physical-social interactions than influence basin-scale water cycles, an integrated research approach is needed to address the critical knowledge gaps.

Research Agenda:

The goal of this research is to improve our understanding of the physical processes governing the hydrology of the region, and of the economics of water use and water transfers. This research will provide the basis for improved future policy and management by agencies and utilities such as the Salt River Project.