Climate and water availability indicators in Canada: Challenges and a way forward. Part III – Future scenarios

Following from Parts I and II of this series (this issue), some common approaches for developing and assessing future scenarios of water availability are reviewed, along with recent case studies of Canadian watersheds. The results of future changes in drought related to climate change are influenced by the choice of indicators. For the Standardized Precipitation Index (SPI), small changes in drought frequency and severity are projected over southern Canada, reflecting the influence of increases in future annual precipitation only. However, assessments using the Palmer Drought Severity Index (PDSI) reveal dramatic increases in the potential for future droughts since this indicator incorporates the combined influences of higher temperatures, soil moisture capacity and precipitation to estimate evapotranspiration. Regarding projected changes in runoff, watersheds in British Columbia tend to show increases in annual and winter runoff. Some watersheds show projected decreases in summer runoff. In the southern ...