Impact Study of Climate Change on Runoff in the Yuanjiang River Basin

摘要

Global warming induced by an increasing concentration of greenhouse gases in the atmosphere would change global and regional climate and produce a significant influence on natural resources and environment. On the basis of a water balance equation in the unsaturated zone and digital elevation model, a monthly hydrological model characterizing heterogeneity of soil moisture content is developed. The model is calibrated and validated using monthly streamflow in the Yuanjiang basin on different spatial and temporal scales. Future possible runoff changes in the Yuanjiang basin is then simulated on the basis of the future climate scenarios predicted by the global climate model (GCM). Simulation results demonstrate that annual runoff in the Yuanjinag basin is very sensitive to temperature rises and rainfall changes. From prediction results in the middle of 21st century presented by the Hadley Centre for Climate Prediction and Research (HCCPR.UK) (HADCM2), we know that mean annual temperature would increase 1.55 "C and precipitation decrease 0.43 percent in the Yuanjiang basin, and monthly rainfall would increase in flood season but decrease dramatically in drought season. Simulated results indicate that annual runoff would decrease 6.8 percent, and runoff in flood season increase 11 percent and in drought season decrease 47 percent. Therefore relative changes in runoff are much greater than changes in precipitation. Changes of future runoff are not beneficial for flood defense and water resource utilization in the region.