元谋干热河谷坡面径流蓄积过程中的面源污染物变化

在元谋干热河谷选择严重干扰退化草地、采取"封禁"和"封禁+等高反坡阶"植被自然恢复草地,布设集水系统对3种草地的径流进行拦截和蓄积,并对2008年雨季和之后的地表径流总氮、总磷和化学需氧量浓度进行测定,结果表明:自然恢复植被能大量减少坡面径流和泥沙产生量,进而大幅度减少面源污染物的输出。坡面径流收集过程对径流拦截和沉砂过程中面源污染物的浓度有较大的削减作用,径流从沉砂池进入蓄水设备,使总氮和总磷浓度分别削减46.63%和38.08%,地表径流在蓄水设备中贮存会使径流中的面源污染物浓度得到进一步削减,证明水土流失防治措施在削减面源污染物输出中有显著作用。

Change of Non-Point Pollutant During the Accumulation Process of Slope Runoff in the Dry-Hot Valley in Yuanmou County

The ’grazing closure’ and ’grazing closure + anti-slope contour stairs’ measures integrated with water harvesting engineering were conducted on 3 types of severely degraded meadows to intercept and gather runoff in Yuanmou dry-hot valley in order to promote the natural recovery of the grass vegetation.The total nitrogen content(TN),total phosphorous content(TP),and chemical oxygen demand(COD) of the slope runoff in the rainy season and later on in the dry season of 2008 were determined.The results showed that restoration of the natural vegetation could greatly reduce the slope runoff and soil erosion,so as to greatly reduce the output of non-point pollutant.The slope runoff collection process included runoff interception and sand sedimentation that could significantly reduce the concentration of the non-point pollutants.It was showed by the study that the concentration of TN and TP was deducted by 46.63% and 38.08% respectively in the course while the runoff flowed from the sand setting pound into the impounding basin.The concentration of the non-point pollutants in the runoff water storage system could be further reduced,so it was demonstrated that the soil and water erosion control would play an important role in cutting down the non-point pollutant output remarkably.