Relationships between landscape, runoff, and sedimentation in wind-water erosion crisscross region
[Background] Sedimentation and runoff variation caused by land use change has been emerged as one of the popular topics of discussion.And the phenomena is more obvious in wind-water erosion crisscross region than in other erosion region,thus it is necessary to study the effects of land use change on runoff and sediment in wind-water erosion crisscross region.Xiliu Gully watershed is the typical watershed in wind-water erosion crisscross region.[Methods] In order to meet the demand of ecological environment construction and comprehensive utilization of water and soil resources,and to put forward an actual production theory for our river basin management,relationships between landscape,runoff,and sedimentation were studied on the basis of long-term historical land use,runoff,and sediment data (1985-2010) by geographic information system and Fragstats software.[Results] 1) According to the Landsat TM data in 1985,1996,2000 and 2010,the spatial variation characteristics of the landscape pattern were analyzed.Grassland was the dominant landscape in the watersheds.Farmland,forest and construction land were in the highest stability,and the second main landscape type was unused land. Unused land,grassland and farmland experienced the greatest changes,which were suffered seriously from human activities.2) Precipitation,annual runoff and sediment changed significantly in last 50 years,but the variation amplitude of them was different.Average precipitation from 1960 to 2010 changed not so obviously,however runoff and sediment were decreased significantly.Moreover,the decreasing trend of runoff was more obvious than sediment in the same year.A Pearson correlation analysis showed that there was a significant correlation between annual runoff and sedimentation (P ＜ 0.01).3) The variation of landscape status played an important role in the progress of precipitation to runoff,which not only inflected the output of the runoff and sediment,but also changed the mechanism of the rainfall to runoff.The main landscape ecological indexes,such as patch density,largest patch index,patch and spent landscape,et al.were analyzed,and the relationships between landscape pattern and runoff,sediment were studied.The Pearson correlation analysis showed that the landscape indexes (shorted for Lis) were in significant linear correlation with runoff and sedimentation.Largest Patch Index (LPI),Patch Cohesion Index (COHESION),Aggregation Index (AI) and Contagion Index (CONTAG) were negatively correlated with annual runoff,whereas Landscape Shape Index (LSI) and Landscape Division Index (DIVISION) were positively.CONTAG,AI and COHESION were negatively correlated with annual sedimentation,whereas other landscape indexes were positively.[Conclusions] From soil and water conservation in the watersheds,it was useful to increase soil infiltration and reduce soil erosion by improving LPI,COHESION,AI and CONTAG,which was also useful for the ecological construction and soil water resources utilization.
国家科技期刊平台
NSTL
万方数据
维普
