The Runoff Simulation Of SWAT Model In Mountain Tai Yaoxiang Small Watershed

Water is essential for human survival and development of natural resources, Who plays an important role in social and economic development.People depend on water for survival and development. But with the increase in population, human living standards and economic development, human demand for water is increasing, meanwhile lakes and other water pollution is becoming more and more serious, so that the amount of available water resources continued to decline, which further exacerbated the conflict between humans and water resources. The result is what direct impact on the sustainable use of water resources.Water construction of ecological civilization is a series of large and complex project. Facing the new era of reform and development needs and water conservancy construction of ecological civilization, some new problems need to be addressed. The theory of evaluation of rivers and lakes ecological health is a fundamental scientific problem of water ecological civilization construction. However, many theories of ecological health of rivers and lakes evaluation stay in the qualitative analysis, evaluation of relatively small magnitude. This requires us to study a quantitative evaluation method for the ecological health of rivers and lakes theory.The impacts of human on the aquatic environment can be manifested by changes in runoff. Distributed hydrological model SWAT (Soil and Water Assessment Tool) is a hydrological model developed by the U.S. Department of Agriculture (USDA) Agricultural Research Center in1994. This model has a strong physical mechanism. It can simulate a wide range of complex hydrological processes within the watershed; It can simulate a variety of non-point source pollution load (such as sediment, pesticides, nutrients, etc.) over time and space migration changes; It can predict the response of basin runoff, sediment and water environment pollution process to climate, management measures, land use, and so on. Yaoxiang small watershed located in Huangqian small watershed which is Tai’an city water source, is the typical small watershed in taishan area. This paper choose the SWAT model as Yaoxiang small watershed impacted by Human runoff change way of analysis, The main research contents are as follows:(1) Summarizes the research status of SWAT model at home and abroad, briefly introduces the development, principle and structure of SWAT model. (2) Selecting taishanyaoxiang small watershed as the research object, The paper using SWAT model combining with the basin digital elevation map, land use map, soil map, land use data, soil data, meteorological data and the runoff data established the distributed hydrological watershed model for the small watershed.(3) For yaoxiang small watershed month runoff simulation, using the naxi coefficient as the model accuracy evaluation criterion, and the analysis of the correlation between simulated values and the measured values, achieved good simulation results. The results show that the SWAT model can be applied to yaoxiang small watershed runoff simulation.(4)Determined the SCS runoff coefficient (CN2), soil evaporation compensation coefficient (ESCO), base flow a (ALPHA_BF),soil available water quantity (SOL_AWC), shallow groundwater runoff coefficient (GWQMN) and saturated hydraulic conductivity coefficient (SOL_K), which had a greater influence on the small watershed runoff, adjusted these parameters reasonably and the model has higher precision.(5) By setting four kinds of human influence land use scenarios, it was concluded that the change of runoff at the exit of yaoxiang small watershed, which reflected the change of the small watershed runoff under the influence of human, and then quantitatively reflects the changes of small watershed ecological health.Thesis research results provided the certain basis of water management, ecological construction and protection for yaoxiang small watershed, in order to provide the basis for Tai’an City approximate watershed ecosystem health assessment, promote the shandong province water ecological civilization construction.