Search

The hydrological cycle is sensitive to the driving forces of climate change. Thus, impact assessment of climate change on water resources from the past to the present is of grave concern for basin management. In this study, water resource spatiotemporal patterns exposed to IPCC scenarios A2 and B2 in the upstream Yangtze River are assessed. Statistically downscaled precipitation and temperature are analyzed. Rainfall-runoff processes are modeled using a distributed hydrological model. Results show that the historical downscaled precipitation and temperature are consistent with observations. Mean air temperature increased for both scenarios. Precipitation generally declined over the region. Runoff is predicted to decrease in most rivers, especially in the wet season, and the variation of hydrographs is obvious. An increase in temperature likely caused the reduction of precipitation leading to the consequent rise of evapotranspiration and decline of surface water and groundwater recharge. Generally, surface water and ground water recharge declined faster in the A2 scenario than B2. Water resources will be in a considerable heterogeneous pattern driven by climate changes. Precipitation, surface water generation, and groundwater recharge share identical spatiotemporal patterns but are predicted to show larger spatial variation in future decades. B2 shows a larger future spatial variation, which may add risks for local droughts and floods. This paper emphasizes the evolution of spatiotemporal variations of water resources from 1999 to 2099 associated with discussions on implications and uncertainties in the upstream Yangtze River region. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the spatial variation of sediment yield in the Yangtze basin in China, a large basin with complex geology, climate, land-use history, and extensive sediment monitoring. 287 stations with drainage area less than 10,000km2 were used to study the scale effects of sediment yield. In order to develop scale relations for regional sediment yield, the whole study area was divided into eight sub-basins. Relation between specific sediment yield and drainage basin area was built for each sub-basin. Regional scaling relation was analyzed based on landforms, geology, lithology and land-use of each sub-basin. Three regional trends were identified in relation to the drainage area: (1) a declining trend, due to soil erosion on heavily cultivated steep land and the storage of sediment in floodplains; (2) a flat trend, due to mass movement on the upper reach and heavy agricultural disturbance on the middle and lower reaches; and (3) an increasing trend, due to downstream recruitment of sediment from land downstream where slope farming and deforestation occurred. Using these developed relations, areally adjusted sediment yield maps were created over the entire Yangtze basin. [Copyright &y& Elsevier]