金沙江干热河谷典型区段水土流失特征

以金沙江干热河谷典型区段不同处理坡面和林地、农地集水区为研究对象,采用坡面径流小区和集水区卡口站三角形薄壁堰实测法,在坡面径流小区和集水区土地利用现状调查基础上,通过降雨、径流及泥沙观测,分析金沙江干热河谷典型区段水土流失特征。结果表明:(1)不同处理坡面径流小区产流量、产沙量大小依次为坡耕地>自然坡面>水平阶整地>反坡台整地,表明反坡台和水平阶造林整地以及植被良好的自然坡面对地表径流的拦蓄和对泥沙的削减都起到较好效果;(2)大暴雨对集水区尺度产流产沙贡献值大,产流降雨量在4.8～27.6mm区间,农地集水区径流深小于林地集水区,大于27.6mm时,农地集水区径流深反超林地集水区,而产沙量不受降雨量影响,为林地集水区低于农地集水区;(3)径流小区尺度与集水区尺度雨季水土流失起止时间一致,集水区径流系数小于径流小区,集水区产沙量大于径流小区。

Soil Erosion Properties in Typical Section of Dry-hot Valley of Jinsha Basin

Selecting different slope surface treatment,woodland catchment and farmland catchment in the dry-hot valley of Jinsha basin typical section as the research object,using the runoff plot and thin triangular weir methods,surveying present land use patterns and observing the rainfall,runoff and sediment,that was in order to analyze the characteristics of water and soil losses.The results showed that:(1)The losses of runoff and sediment in 5 different processing slope plots was the following order: Sloping land >natural slope >level terrace >anti-slope terrace.This showed that afforestation of the anti-slope terrace and level terrace and good vegetation were good at closuring runoff and reducing sediment.Increasing vegetation covers were remarkable in the fact of reducing sediment.(2)Extraordinary rainstorm contributed the value to runoff and sediment of two catchments.When rainfall was 4.8 mm to 27.6 mm,the farmland catchment’s runoff trend was less than the woodland catchment’s and if rainfall was greater than 27.6 mm,the results was contrary.Sediment yield of woodland catchment were lower than the farmland catchment.(3)During the rainy season the runoff and sediment beginning and ending time of plot were consistent with catchment’s.Rainy runoff coefficient of catchment was less than the runoff plots.Catchment’s sediment yield was greater than the runoff plot value.