Enhancing Water Governance for Climate Resilience: Arizona, USA—Sonora, Mexico Comparative Assessment of the Role of Reservoirs in Adaptive Management for Water Security

Climate variability and change exert disproportionate impacts on the water sector because water is a crosscutting resource for food production, energy generation, economic development, poverty alleviation, and ecosystem processes. Flexible surface water and groundwater storage together with adaptive water governance are increasingly recognized and deployed to strengthen climate resilience, specifically by buffering drought and flood extremes, bridging interannual variability, and providing for multiple uses of water, including environmental flows. Adaptation can be further enhanced by the following: (1) accounting for hydroclimatic and water-demand uncertainties; (2) strengthening institutional learning in relation to reservoirs (reoperations as well as mechanisms to address growing civil-society critiques of “hard-path dependence”); (3) increasing flexibility of policies for infrastructure (including readaptation to past cycles of infrastructure development); and (4) building on science-policy dialogues that link infrastructure and governance. An array of complementary adaptation tools will buttress climate resilience. Some emerging techniques include underground storage, distributed basin-wide enhancement of water retention, efficient water use (with limits on the expansion of new demands on saved water), and wastewater reclamation and reuse (with their own emerging storage and recovery techniques). Each of these techniques is directly linked to reservoirs in practical and operational terms. Conjunctive surface-water and groundwater storage must be further developed through infrastructure, institutional, and policy approaches including groundwater banking, trading and credit schemes, water swaps (substitutions and exchanges), and a robust approach to targeted water storage for climate resilience.