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近50 a来,在气候变化和生态恢复与治理工程实施的背景下,黄土高原的侵蚀产沙特征发生了明显的变化。以黄土高原典型中尺度流域清水河流域(面积436 km2)为研究对象,利用1959、1986、2007年的土地利用解译结果和1960—2005年该流域实测输沙和降水资料,采用非参数Mann-Kendall趋势分析法和滑动t检验法研究了该流域年输沙量、降雨量的变化趋势和突变点,并与通用土壤流失方程相结合分析了该流域土地利用和降雨变化对输沙量变化的贡献率。结果表明:该流域年输沙量47 a间有显著的下降趋势,突变点位于1980年;降雨量没有明显的趋势性变化,极端降雨指数下降。降雨因素对输沙量减少的贡献率为9.89%,土地利用的贡献率为90.11%,土地利用变化中工程措施淤地坝的贡献率为5.56%,植被变化的贡献率为84.55%。该流域47 a间乔木林地面积增加了944.27%,灌木林地增加了19.33%,表明清水河流域林地面积增加是导致输沙量减少的主要原因。
In the recent 50 years, under the background of implementing the project of climate change, ecological restoration and harnessing, the characteristics of erosion and sediment yield in the Loess Plateau have undergone significant changes. Taking Qingshui River basin (area 436 km2) as a typical mesoscale watershed in the Loess Plateau as the research object, using the interpretation results of land use in 1959, 1986 and 2007 and the data of actual sediment transport and precipitation in the basin from 1960 to 2005, The trend and the change point of annual sediment load and rainfall in the basin were studied by Kendall trend analysis and sliding t-test. Combined with the general soil loss equation, the change of sediment load by land use and rainfall was analyzed The contribution rate. The results show that there is a significant downward trend in annual sediment load in the basin for 47 years, with a sudden change point in 1980; there is no obvious trend change in rainfall, and the extreme rainfall index declines. The contribution rate of rainfall to the decrease of sediment transport is 9.89%, and the contribution rate of land use is 90.11%. The contribution rate of siltation dams to engineering measures in land use change is 5.56%, and the contribution rate of vegetation change is 84.55%. The area of arbor forest increased by 944.27% and that of shrub land increased by 47.33% in the 47th year, which indicated that the increase of forestland area in Qingshuihe River basin was the main reason for the decrease of sediment load.