The Study On Simulation/Forecanst Of Surface Runoff And Function Conversion From Dam To Reservoir In Small Watershed Under The Changing Condition

Water resource is the basic and strategic one in human’s survial and development. The water resource assesment is very necessary and important during the water activity and management. Menawhile, the evaluation is the base of efficient use, scientific allocation and sustainable development of water resource.Along with the change of climate and underlying surface condition, the devolvement rule of water resource in the watershed. The southland of Ningxia belongs to the Liupanshan district. The region is the only green island and natural oxygen bar in the loess plateau. At the same time, it is sensitive and strong to the climate change in the region. In the thesis, haoshuichuan watershed was choosen as an study example. Through field investigation, data analysis, local observation and software simulation, the surface water resource under the changing condition was simulated and forecasted. The main content can be divieded into five parts.The first part is the general situation of the study area. By means of field reserch and data collection, the fundamental state, such as physical geography, hydrology-weather condition, landuse, water and soil loss, water resources development and utilization, engineering operation were expounded. Then the problems in the water resoure were concised.The second part is the evaluation and Space-time forecast of precipitation. The basic law, which inclueds the year&perennial distribution, variation trend was analyzed. The thesis choose the observed datas of1951-2010, combines the markov and cycle extension superimposed methods to predict the rainfall. In addition, the isoline of rainfall was charted to analysis the spatial distrrbution quantitatively.The third part is study of transformation mechanism during the surface runoff. By analying the characters of rainfall and aeration zone, it is ditermined that the pattern in the watershed is infiltration excess runoff. And the influence factors are the amount and intensity of the rainfall, initial moisture in the soil.The fourth part is the surface runoff simulation and analysis under different rainfall and landuse. First, it is necessary to build the digital watershed model. Then, the CASC2D model was selected, which has strong physical infrastructure. Afte that, the relevant parameters were verified and calibrated. Afterwards, different combination of rainfall and landuse were degined to simulate the runoff. Finally, qualitative analysis of the influence of rainfall and landuse to runoff was finished. And the result can be used to guide the plan of water resource and land utilization.The fifth part is the surface runoff forecast. Based on the SCS model, uniting the precipatation prediction, the runoff forecast model was established, which can be used to make the quantitative forecast of runoff in the watershed conveniently.Based on the five parts, the thesis purposed the fuction division and position system and indexs of the dams. Some dams can be used as reservoirs. So, the the utilizable quantity and efficiency of resources in the valley will be increased highly.