Research On Response Of Runoff To Land-Use Change In Xiangxi River Watershed

In recent years, response of resources and environment to land use change arouses broad attention in region scale. One of responses of environment to land use change is hydrolody response. In given region, making clear the relation of land use change and hydrology change is a main measure, which is used to analyse policy domino offect in region resources, environment and zoology matters. The paper chooses Xiangxi River watershed as the example to study the response of the various landuse to runoff runoff, the influence of land use change to river runoff, space-time distribution of precipitation and adjustment of ruoff by forest cover. The results were of important meaning to understand the characteristics of water and soil resources and the rule of runoff producing and to improve the research on the sensitivity and frangibility of water resourses, according to which to take corresponding measures.The paper choosed distributed hydrological model SWAT (the Soil and Water Assessment Tool) to simulate and study the hydrologic response in the research area.Based on GIS, the spatial database (integrating DEM, soil, and landusemap et al.) and non-spatial database (integrating climate, and land management data et al.) were established.With the support of SWAT model, the 17 sub-watersheds have been automatically delineated by the DEM and waterstreams. And the model has been calibrated and validated with the real data collected from the study area in the years from 1971 to 1989. In calibration and validation period occurred in years, relative coefficient are 0.77 and 0.83, Nash-Suttcliffe coefficient are 0.72 and 0.67, In calibration and validation period occurred in momths, relative coefficient are 0.82 and 0.77, Nash-Suttcliffe coefficient are 0.77 and 0.74. The results show that SWAT model could be successfully used to model this area.Based on simulating results, taking Xiangxi River watershed as the example, the paper analysed contribute of various land use to runoff. The result indicated that the runoff depth produced by gradient plantation was the most,(637.5mm), terrace plantation taked second place and woodland was the lest (546.99mm).The most, gradient plantation, was 1.16 times of the least, woodland.The paper studied another factor by fixupping one factor, which affected runoff. It analyzed the influences of landuse change runoff. The result showed that the sum of runoff was disceased by the change of land use from the circumstance in 1980s to 1990s.Adopting scenes analyse method to simulate the relationship of precipiotation and runoff under the condition of various precipitation and forest cover.The result showed runoff increased along with prepication increasement and decreased along with forest cover increasement.