research is also needed on effective decision-support tools, such as forecasts, climate services, and methods for making complex trade-offs under uncertainty (see Chapter 4 for additional details).
Impacts of climate change on diverse water uses. Climate change will affect many water-related activities and sectors, including navigation, recreation, tourism, human health, drinking water, agriculture, hydroelectric power generation, and the ecological integrity of aquatic and terrestrial ecosystems. Continued and expanded research in all of these areas, and on the economics of water supply, demand, and costs of adaptation, is needed across and between different water-dependent sectors. The potential for local, state, and international disputes over water resources is also an area where further study is warranted (see Chapter 16). Another need is for better understanding of how institutions and behavior shape vulnerability and offer opportunities to adapt to changing water regimes.
Develop vulnerability assessments and integrative management approaches to respond effectively to changes in water resources. Changes in water resources are anticipated to affect coupled human-environment systems in a variety of ways and in interaction with many other environmental stresses. Assessing which water supplies and human-environment systems are most vulnerable to climate change will require analysis of place-based environmental conditions as well as social conditions and management needs. Frameworks need to be developed and tested for such assessments, and new integrative water resource management and adaptation approaches are needed for managing water in the context of climate change. Finally, the effects of actions taken to limit the magnitude of climate change (or adapt to other impacts)on water resources need to be more systematically assessed and accounted for in climate-related decision making.
Increase understanding of water institutions and governance, and design effective systems for the future. Water institutions of the future will have to deal with the complexity of multiple and interacting stresses as well as equity and economic issues related to water use. Reconciling water entitlements across different water systems, making water systems more flexible in the face of change, and shaping an institutional environment that encourages water conservation and reuse are only some of the challenges facing water resource institutions as climate change progresses. To improve our ability to design and deploy water institutions, more research is needed on governance mechanisms such as water markets, public-private partnerships, and community-based management. Evaluation of legacy effects of past infrastructure and management decisions will assist in understanding path-dependent effects, but only to the extent that such lessons are relevant to constantly evolving conditions.