Hydrologic impacts of climate change in gauged and ungauged watersheds of the Olifants Basin

Abstract

Robust projections of climate change impacts on regional hydrology are crucial for water resources management, especially in data-sparse regions. Impact projections have to: (a) be available at gauged and ungauged locations; (b) consider changes in watershed behaviour for different future climates and land uses; and (c) include estimates of uncertainty. We apply a novel water resources modelling framework which combines signature regionalization with the trading of space for time to obtain hydrological projections in ungauged basins and under climate change for the Olifants basin in southern Africa, a UNESCO HELP basin. We find that using statistically downscaled general circulation model (GCM) vs observed climate data leads to only slight deterioration in reliability of runoff projections for the historical period. The framework projects a decrease in regional runoff by –8.7% and –3.9% for A2 and B1 scenarios, respectively, by the end of the century, with, 80% and 67% of GCMs agreeing on the decrease in runoff, respectively.