PNNL

Abstract

This paper explores how changes in water demand trigger different response mechanisms to potential water scarcity by different economies. Using a model of integrated human-earth system dynamics (GCAM), and assuming water supplies remain constant at today’s levels, we test a wide range of alternate water demand scenarios to explore whether socioeconomic changes or the choice of energy technologies affect individual basins’ primary adaptation strategy. To illustrate different responses, we use a typology that categorizes countries and basins according to their adaptive changes in electricity and agriculture. Three different categories are found. First, little adaptive change is observed for many basins (i.e., water withdrawals are not reduced in either sector) as water demand variations do not cause scarcity. Second, adaptation mainly occurs through the energy sector (e.g., most basins in the Unites States and China) with a transition to water-saving cooling systems but marginal impact on total power generation or the fuel mix. Third, where there is a lack of sufficient adaptive capacity in the power sector (e.g., Pakistan, Middle East and several basins in India), additional adaptation occurs through reduced irrigation water withdrawals, either by switching from domestic production to imports or from irrigated agriculture to rain-fed production. The primary response mechanism to demand-based water scarcity for individual basins is quite robust across the range of water demand scenarios tested.