Author(s): Yangwen. Jia; C; Xiangyi Ding; Cunwen Niu; Yaqin Qiu
Keywords: Hydrological simulation; Climate and land use changes; Mountain area
Abstract: The Taihangshan mountain area of the Ziyahe River Basin with a command area of 30703 km2 is an important water source area for the downstream North China Plain and Beijing city. Due to the climate change and human activities including land use change and dam constructions, annual and seasonal distributions of water resources in the area have been greatly changed, which threatens both the water supply safety of local economy and eco-environmental flow of the downstream Ziya River. In this study, a distributed hydrological model, water and energy transfer processes (WEP-L) model, was developed to simulate temporal-spatial variations of water resources in the study area. Modeling approach of every component process was introduced. The hydrological processes include evapotranspiration, infiltration, runoff, groundwater flow, interaction between groundwater and river water, overland flow, river flow and water utilization processes. A simulation of 50 years from 1956 to2005 was carried out. The model was validated for the simulation of monthly discharge process at the Huangbizhuang gauge station (23400 km 2) with the Nash-Sutcliffe coefficient larger than 0.65 and the determination coefficient over 0.8. Water budgets and spatial and temporal variations of hydrological cycle components were studied by using WEP-L. The modeling results show: (1) the annual average evapotranspiration and runoff account for 83%and 17%of the annual precipitation (530mm), respectively, and the groundwater storage has no obvious change; (2) the annual naturalized runoff shows a declining trend because of the precipitation decease, land use change, dam construction and water consumption, with the runoff of 1980-2005 reduced 24%than that of 1956-1979; (3) the water resources shows obvious seasonal changes with over 65 percent in the late Summer and early Autumn seasons (July-October), which easily leads to drought issues in the mountain area.