Impacts of climate variability and change on hydrology and water resources in the Yellow River basin

Climate variability and change have great implications for the hydrological cycle and water resources planning. In order to assess these impacts, a semi-distributed monthly water balance model was proposed and developed to simulate and predict hydrological processes in the middle and lower Yellow River basin. GIS techniques were used as a tool to analyse topography, river networks, land use, human activities, vegetation and soil characteristics. The model parameters were calibrated in 35 gauged sub-basins in the middle Yellow River and linked to ungauged sub-basin characteristics. A parameterization scheme was developed and the model parameters were estimated for each grid element by regression and optimization methods. Based on the different GCM and RCM outputs, the sensitivities of the Yellow River hydrology and water resources to climate variability and global warming were studied. The proposed models are capable of reproducing both the magnitude and timing of runoff and water resources conditions. The runoffs are very sensitive to temperature increase and rainfall decrease. Results of the study also indicated that runoff is more sensitive to variation in precipitation than to increase in temperature. Climate variability and change challenge existing water resources management practices with additional uncertainty. The presently planned water resources systems in the Yellow River basin do not consider the possible effects of climate variability and change and cannot satisfy the increasing water demand by the year 2030. Integrated water resources management will enhance the potential for adaptation to change.