Variability of and climate change impacts on the terrestrial hydrologic processes

Abstract

To explore the variability of and climate change impacts on the terrestrial hydrologic processes, this study conducts the investigations of simulating the terrestrial hydrologic processes, analyzing the variability and interaction processes and exploring the variations in climate and hydrology in the future. Meanwhile, this study improves a reservoir operation scheme for the multiyear and multipurpose reservoirs to enhance the performance of hydrologic models.

Driven by the 12-year (1997-2008) meteorological forcing data, and the soil and vegetation data, the Variable Infiltration Capacity (VIC) model, is applied to simulate the terrestrial hydrologic processes over the five major river basins in the world, including the Amazon River basin, the Mississippi River basin, the Nile River basin, the Nile River basin and the Yangtze River basin. Based on the VIC simulations, this study explores the temporal and spatial variations of main hydrologic variables, such as precipitation, evapotranspiration, streamflow and soil moisture over these river basins. The strong non-linear relationships between precipitation and runoff presented reveal the complex interactions between the hydrologic cycle and the climate system.

Further, an operated-based reservoir scheme using VIC model as the platform is enhanced. This reservoir operation scheme is applied to simulate the variations of outflow and storage for the multiyear and multipurpose reservoir, Xinfengjiang Reservoir, over the East River basin in South china. The enhanced reservoir scheme provides a simple but effective method to represent the proportions of various operation purposes, such as water supply and power generation.

Using the climate model outputs for 100-yr time periods (2000-2099) from 16 GCMs at three carbon emission scenarios, SERS A2, SERS A1B and SERS B1, this study investigates the changes in climate in the future over the Pearl River basin in South China. The results suggest that the rainy season will be wetter and the dry season will be dryer in the future for the Pearl River basin.

Furthermore, through the application of the Morlet wavelet analysis to the individual sub-basins of the Pearl River basin based on VIC simulation results, the variability features of the terrestrial hydrologic processes at various scales are studied. The analysis indicates the higher possibility of the occurrence of the water-related hazards in the middle century. Meanwhile, the power Hovmӧller analysis of streamflow and soil moisture anomalies suggests that the western part of the Pearl River basin experiences more severe streamflow and soil moisture variations in the future.

Overall, this study provides investigations about the variability of and impacts caused by climate change to the terrestrial hydrologic processes. The results would benefit the water resources management and water-related hazards mitigation and prevention.