Study On The Relationship Between Vegetation And Water Resources Base On Wulanmulun SWAT Model

With the development of energy and economic, the requirement of water has rapid increased in Ordos. It is important of investigating the water resources. We must know how the water move and transform in Ordos and what controls it, So we can make a good plan for water use.Distributed hydrological model SWAT has strong physical simulation capability. It can simulation most of hydrology processes, such as rainfall, evaporation, pant growth, soil water, Lateral flow of soil, surface runoff, river runoff and agricultural management etc. It is a good distributed hydrological model for study the watershed of Wulanmulun river in Ordos. And by the model we got some results as follow:1,We have ranged the sensitivity factors which effect water movement and trans- formation in the watershed by sensitivity analysis of SWAT. The SCS curve number is the most sensitive factor, and followed by soil depth, soil water content, soil evaporation compensation factor, max leaf area index.2,As SWAT model rarely used in Northwest China, this paper discusses it's adapt- ability in the watershed of Wulanmulun river. We found the reliability of simulation relate to precipitation. When precipitation less than 300mm simulation results is not satisfactory, on the contrary when precipitation close to 400mm the simulation results fit well with the actual values.3,What's the relationship between water yield factors and rainfall? The study proved rainfall impact on water yield factors, and they have different relationship. Lateral flow of soil changes with variation of rainfall in the same time. Surface runoff is rarely in a year, and only in rainstorms. Groundwater contribution to stream flow is about a month later than rainfall. Water yield mainly composed of lateral flow of soil and groundwater contribution to stream flow.4,How vegetation influence water movement and transformation in the study area? The simulation have shown increase in vegetation lead to decreased water yield, soil water content, sediment yield and increased evaporation.5,By analyzing the Ordos vegetation, rainfall and water, and referencing Wulanmulun river SWAT model, we know increasing vegetation is the primary reason of shrinking lakes, falling water tables and other water crisis. In conclusion we should keep vegetation at an acceptable level. But not blind to plant trees and grass in order to increase the number of vegetation.