Introduction

Water stress is an increasingly important challenge for the twenty-first century. Demand for water resources in agricultural, municipal, industrial, and environmental uses is rising due to population and income growth. Climate change is expected to exacerbate water stress by increasing the frequency and severity of extreme weather conditions. Although drought may not become more frequent or severe in all locations, growing demand for water will cause scarcity to become more pressing over larger geographic areas. In many locations, infrastructure to store and release water currently lacks the capacity to meet demand during drought periods and prevent floods during wet periods. Competition for scarce water resources, both within and among sectors, will place even greater pressure on existing infrastructure, as well as current water allocation institutions and management policies.