Study On The Soil Water Resources Of The Whole Watershed Controlled By The Bengbu Station

The Huai River Basin is located in central China and with a superior geographical location. However, precipitation in Huai River Basin is unevenly distributed in spatial and temporal that results in the lack of water resources, and it has become one of the major problems that limits the sustainable development in economy and society. By studying the methods for evaluating soil water resources(sW), it is able to reasonably regulate water resources in a watershed from the point of view of regional water cycle. Water conservation could be achieved as well as guarantee in agricultural water demands. Major contents and achievements are list as follows:(1) Evaluation methods were summarized in this paper, and Evaluation indexes include capacity of soil water storage, the maximum capacity of soil water storage, sW have been effectively utilized(fW), SWR that cannot be utilized(uW). Meanwhile, calculation method for the study area in the watershed controlled by the Bengbu station has been determined.(2) Primary data that used for model building have been collected, and model for hydrological cycle in the study area can be achieved by processing the study area through spatial discretization method. SUFI-2 method is introduced to conduct the sensitivity analysis. This paper analyzes sensitivities of related parameters in four stations(Xixian, Wangjiaba, Lutaizi, Bengbu), and the most sensitive and significant parameter has been determined for each station.(3) Data series from 1991 to 1997 are used for parameter calibration, and parameter verification uses data from 1998 to 2000. During parameter calibration, coefficients of each station demonstrate: R2 in the Xixian station is 0.87, and its NS equals to 0.86; R2 and NS in the Wangjiaba station both are 0.91; R2 in the Lutaizi station is 0.91, and its NS equals to 0.90; R2 in the Bengbu station is 0.92, and its NS equals to 0.91. All of the coefficients are larger than 0.8 when conduct the parameter verification.(4) We utilize the SWAT model to simulate hydrological cycle in the study area. Results show that the annual average sW during 1991~2000 are 438.59 mm, and fW are 347.11 mm. Spatial distributions of the latter relate closely to the precipitation, which means a region with heavy precipitation has largerfW.(5) In order to better understand the distribution of fW, this paper choose 1933 as a representative year to further investigation. The average sW in representative year are 448.91 mm, and fW are 361.96 mm. Results of spatial distribution shows that fW in the southern regions are higher than that of northern region, and it is mainly distributed around the main stream of the Huai River. Results of temporal distribution shows that fW along with changes in precipitation and evaporation, and has a significant variation in flood season.