Hydrological Response To Climate Change In Typical Catchments

During past decades, climate change and human activities have caused significantchanges in water resources. Analysis of hydrological responses to climate change isscientifically significant for improving our understanding of watershed hydrology andpractically significant for improving our water resources management. In this thesis,typical catchments with different climatic and land use/cover conditions were selectedas study areas. The hydrological responses to climate change were analyzed usingdifferent models, including a statistical regression model based on observation data, alumped conceptual model and a distributed hydrological model. The impact of climatechange and human activities on runoff change were quantitatively evaluated.A climate elasticity model and a water-energy balance model with theconsideration of impact of interannual variability of water storage in watershed wereproposed by introducing the concept of antecedent precipitation. Based on the improvedwater-energy balance model, the climate elasticities of runoff were derived analytically.Both models were employed to quantitatively evaluate the effects of climate variabilityon runoff for296typical catchments in China. The distribution of elasticities showed agood consistency. Results showed that annual precipitation is the most important factoraffecting the change in annual runoff. For humid catchments (the arid index is less than1.0) in China, change in annual precipitation by a1%(about14.3mm) could produceabout an average of a2.1%(about3.3mm) change of runoff. For arid catchments (thearid index is more than1.0) in China, change in annual precipitation by a1%(about5.7mm) could produce about an average of a2.1%(about3.3mm) change of runoff.Moreover, the climate elasticity model was employed to quantitatively evaluate theeffects of climate variability on runoff and vegetation cover for193typical catchmentsin Australia. For all catchments, change in annual precipitation by a1%(about9mm)could produce about an average of a3.3%(about5.1mm) change of total runoff, a3.5%(about2.6mm) change of surface runoff and a2.9%(about2.5mm) change ofsubsurface runoff. The impact of climate change and land use change on runoff wasfurther quantitatively evaluated for each catchment using the water-energy balancemodel. The land user change was found to be the major reason for runoff change inmost areas of Hai River Basin, Yellow River Basin, lower Songhuajiang Basin and Liao River Basin, while climate change was the major cause for runoff change in othercatchments. Annual runoff for each catchment was predicted using the improvedwater-energy balance model. Compared with observed data, results showed that theimproved model had good simulation ability. The model performance was found to bebetter in humid catchments than that in arid catchments.Aimed at the change of inflow into the Panjiakou Reservoir during past50years,the distributed hydrological model was built in the Panjiakou Reservoir catchment. Themodel was applied to simulate the hydrological processes during past50years. Basedon the simulation results, the long-term change of water balance components, meanannual and annual water balance relationships for sub-catchments were analyzed. Thestatistical regression model, the water-energy balance model and the distributedhydrological model were synthesized together. Based on the three methods of analyzinghydrological responses to changing environments, a comprehensive evaluation methodwas developed to analyze the runoff change, which providing a reference forcomprehensive analysis of hydrological responses under changing environment.The comprehensive method was applied to distinguish the contributions of climatechange and human activities to runoff change during past50years and simulate thepossible runoff change under future climate scenarios in the Panjiakou Reservoircatchment.