Quantifying Surface Water Supplies under Changing Climate and Land Use

This chapter addresses the challenge of quantifying water security under climate and land use change, focusing on surface water supplies. The objective is to illustrate selected quantification challenges and modeling approaches using case studies. The chapter focuses on the supply-demand balance in zones that represent the aggregations of supply to and demand from many thousands of people (or equivalent water demand from agriculture, industry, and other uses). It selects two particular areas of challenge: understanding the impacts of land use change on river flows and incorporating climate change uncertainty into reservoir storage analysis. The chapter also illustrates this focus within the range of topics related to water security. Finally, the chapter discusses how water resources systems have traditionally dealt with uncertainties in inflows and what alternatives are being developed to accommodate for the bigger uncertainties posed by the changing climate.