昆明松花坝水源区坡耕地对集水区产流产沙的影响

Effects of sloping land on the runoff and sediment on catchment area in Songhuaba Reservoir in Kunming

为了研究集水区尺度上坡耕地对产流产沙的影响,选取昆明市松花坝水源区迆者小流域内面积为0.42 km2的集水区(混合集水区,L+P)为研究对象,混合集水区上部为天然次生林(林地集水区,L),中下部为坡耕地。在自然降雨条件下,研究含坡耕地的混合集水区和上部林地集水区的坡面产流、产沙特征。结果表明:1)在强降雨条件下,混合集水区的径流量是林地集水区的9.31倍,且径流系数、流量变异系数是林地集水区的1.14倍和1.43倍;2)林地集水区和混合集水区的产沙量分别为69.76和359.10 t/km2,混合集水区的输沙量变异系数大于林地集水区,主要是林地集水区对泥沙的调控能力相对于混合集水区强,泥沙流失量较小;3)林地集水区与混合集水区的产流量与产沙量单因素差异性分别为0.01和0.001,且产沙量的显著性大于产流量。因此,坡耕地是集水区水土流失量增加的直接影响因素。

[Background] China is one of countries having the most serious soil erosion disaster in the world,it is across the country and it is serious. It is the concentrated reflection of various kinds of ecological problems,and results in the serious threat to food and ecological security. The study of soil and water loss mainly focuses on runoff plots,and the research on catchment area is little. [Methods]Two kinds of catchment area were selected at Yizhe small watershed in Songhuaba Reservoir in Kunming.The area of the mixed catchment area（ L ＋ P） was 0. 42 km2,it included woodland catchment area（ L）and sloping land. Runoff and sediment yield characteristics were monitored continuously under the natural rainfall condition. According to the long-term and effective monitoring data of rainfall,runoff and sediment yield,the dynamic change process of runoff and sediment yield would be quantitatively and qualitatively described. [Results] 1） Runoff of mixed catchment area was higher under the strong rainfall condition,it was 9. 31 times that of the woodland catchment area. Runoff coefficient and flow coefficient of variation were same as the runoff of mixed catchment area,they were 1. 14 and 1. 43 times that of the woodland catchment area respectively. 2） The sediment yield showed significant differencesbetween the woodland catchment area and the mixed catchment area,they were 69. 76 t/km2 and 359. 10 t/km2 respectively. The sediment discharge coefficient of variation in the mixed catchment area was greater than that in the woodland catchment area,because the sediment control ability from woodland catchment area was much better than mixed catchment area,thus sediment losses was smaller. 3） The single factor variance was 0. 01 and 0. 001 of runoff and sediment yield on catchment area,and the significance of sediment yield was greater than the production flow. [Conclusions]Sloping land had the direct effect on water and soil loss in the catchment area. Research of catchment area was more conform to changes under natural conditions; it could avoid deviation from the limits of plot runoff because of area. It could be effectively reckoned up the influence of land-use types on water and soil loss by the runoff and sediment. And it can serve as an important basis for soil erosion control measures.