关键词: 重庆市, 降雨侵蚀力, 时空变化

Abstract:

Soil erosion has become a global ecological and environmental problem. Soil erosion has not only led to the destruction of land resources and reduced crop yields, but at the same time can cause water pollution and reservoir sedimentation, and increase flood risks. Therefore, the evaluation of regional soil erosion risk by analyzing the spatial and temporal variation of rainfall erosivity is of both scientific and practical significances. In the Three Gorges Reservoir Area, the quality of the ecological environment has been directly impacted by water soil erosion, it is necessary to make a study on the temporal and spatial distribution of rainfall erosivity in Three Gorges Reservoir Area and its surrounding regions. This study chose Chongqing as the study area, and used EOF technique and non-parametric Mann-Kendall statistical test to investigate spatial-temporal changes of rainfall erosivity of the study area from 1960 to 2010. Major findings are as follows: 1) There are a spatial distribution pattern of annual rainfall erosivity that it is greater in the eastern area and less in the western area in the study area, while the largest is in Chengkou, Kaixian, Wanzhou, Yunyang and Zhongxian , indicating a higher level of potential hazards in these areas. Seasonal rainfall erosivity has a similar spatial distribution pattern, the rainfall erosivty of spring and winter in the southeast of Chongqing are the largest, followed by the northeastern and the western region, where it is the least; but the rainfall erosivity of summer and autumn in the northeast region are the largest, followed by the southeastern and western region. There is great gradient of annual, summer and autumn rainfall erosivity changes in the area of Fengdu, Zhongxian and Shizhu area, and small gradient of annual, all seasonal rainfall erosivity changes in the western area of the study area. 2) Consistent anomaly distribution is the main spatial pattern of annual and seasonal rainfall erosivity in the study area, which means the trend of changes of annual and seasonal rainfall erosivity at all stations are consistent in the study area, and the pattern was caused by large-scale climate impact factors. The annual and seasonal rainfall erosivity generally tended to increase after the year 2000. 3) Reverse changes in the spatial distribution pattern of annual, autumn and winter rainfall erositivy existe between northeastern region and other regions in the study area due to the mountainous terrain. Whenever the annual and seasonal rainfall erosivity in the northeastern of the study area increases or decreases, correspondently, the annual and seasonal rainfall erosivity in other regions of the study area would show opposite changes trend. The reverse changes pattern of autumn rainfall erosivity was typical in the 1960-1980s, and the pattern of winter rainfall erosivity was typical after the year 2004. The results above will be helpful to the research on the soil and water conservation in Chongqing.

Key words: Chongqing, rainfall erosivity, spatial-temporal changes