Research Of Hydrological Responses To Climate And Landuse Changes In The Sihe Watershed Based On Swat Model

In this study, a SWAT model was constructed in the Sihe watershed. After the sensitivity analysis and evaluation of applicability of this model, it could be used to study land and water interactions of the Sihe watershed. The specific research ideas were displayed as follows:One is to set different climate change scenarios to simulate the effects of climate change on runoff variations in order to discuss the relationships between the climate changes (mainly including temperature and rainfall) and hydrologic responses; Second, to analyze the hydrologic responses to the landuse changes during the different periods in the Sihe watershed. Based on this basis, we analyzed the hydrologic responses to the climate factors and landuse patterns, and explored the watershed hydrological cycle and driving mechanism; finally this study would provide a scientific basis for the protection of water resources and ecological construction in the Sihe watershed. The following are the important conclusions concluded from this study. (1) By SWAT sensitivity analysis, the more sensitive parameters in runoff simulation process in Sihe watershed:Vegetation coverage value under normal circumstances moist, compensation coefficient of soil evaporation, available soil water content, etc. are obtained and the range of the parameters after the calibration are as follows:CN2(73-82); ESCO=0.98; SOL_AWC(0.04～0.2); GW_REVAP=0.02; GWQMN=0; REVAPMN=1.(2) Analyzing the change of average annual runoff with climate scenarios and finding that average annual runoff reduced with temperatures rising, and average annual runoff decreased about1.8%as the temperature increased1℃. Average annual runoff increased15.04%when annual rainfall increased10%, when annual rainfall decreases10%, the average annual runoff decreased10.82%.We can find that annual rainfall was an important factor in affecting runoff, and compared with temperature change, average annual runoff was more affected by annual rainfall than temperature.(3) Comparison of runoff changes under different land-use patterns, we concluded that there was no different in average annual runoff changes among1980,1995and2000, and the monthly average runoff distribution was more consistently. Therefore between1980～2000in the Sihe watershed, land use changes had no obvious influence on runoff changes compared with climates change.This study ultimately found that climate was a major factor in affecting runoff, and the influence of land-use factors was far less than the climatic factors in this time period in the Sihe watershed. Therefore, future water managements of the Sihe watershed should pay attention to climate changes and appropriate management measures of watershed were taken to promote the healthy and sustainable development of the ecological environment in the Sihe watershed.