稻草覆盖对赣南稀土尾渣坡面产流产沙的影响

Effects of Straw Mulching on the Surface Runoff and Sediment Yield of Rare Earth Tailings from Gannan

生物覆盖措施能显著降低敏感脆弱带及裸露坡地水土流失,且具有成本低、见效快等特点,适合在矿区推广.为研究稻草覆盖对稀土尾渣坡面水土流失过程的影响,采用人工模拟降雨试验,对比研究不同雨强(60和90 mm/h)和不同稻草覆盖度(0%、50%和100%)条件下稀土尾矿地表产流、产沙情况.模拟降雨试验在位于江西省九江市德安县的江西省水土保持生态科技园开展,不同雨强采用西安清远测控技术有限公司设计的QYJY-503人工模拟降雨系统进行控制.结果表明:雨强为60 mm/h时,50%和100%稻草覆盖度处理坡面径流开始时间分别比0%稻草覆盖度坡面延迟46%和91%;雨强为90 mm/h时,延迟幅度分别为3.0和4.8倍.0%、50%和100%稻草覆盖度条件下稀土矿渣坡面单位时间产流量分别在产流开始后6、31和41 min达到稳定值.60 mm/h雨强条件下稀土矿渣坡面1 h总产流量呈现0%稻草覆盖度>100%稻草覆盖度>50%稻草覆盖度(P<0.05),而90 mm/h雨强条件下则为0%稻草覆盖度>50%稻草覆盖度>100%稻草覆盖度(P<0.01).雨强为60 mm/h时,50%和100%稻草覆盖度稀土矿渣坡面土壤侵蚀量分别比0%稻草覆盖度坡面降低73.46%和84.53%;而雨强为90 mm/h时,2种措施土壤侵蚀量降幅分别为54.83%和72.14%.研究显示,稻草覆盖措施可以有效降低矿区土壤坡面径流、泥沙产量.

Biological mulching measures can significantly reduce soil erosion for sensitive and vulnerable zones and exposed slopes and have the characteristics of low cost and quick effect,which are favorable qualities for application in mining areas.Simulated rainfall experiments were conducted to compare the surface runoff and sediment yields of rare earth tailings under different intensities of rainfall(60 and 90 mm/h)and rice straw mulching(0%,50%and 100%).The simulated rainfall experiments were carried out in the Soil and Water Conservation Eco-Technology Garden of Jiangxi,which is located in De′an County,Jiujiang City,northern Jiangxi Province.A QYJY-503 artificial simulated rainfall system designed by Qingyuan Xi′an Measurement and Control Technology Co.,Ltd.was used to produce the different rainfall intensities.The results showed that straw mulch resulted in reduced runoff and soil losses compared to bare soil.When the rainfall intensity was 60 mm/h,the runoff initiation time was delayed by 46%under 50%rice straw mulching compared to that under no mulching treatment,and by 91%under 100%rice straw mulching.When the rainfall intensity was 90 mm/h,the delay rates of the runoff initiation time for 50%and 100%of rice straw mulching were 3.0 and 4.8 times,respectively.Under the conditions of 0%,50%and 100%straw mulching,the runoff yield per minute of the rare earth tailing slope reached a steady value at 6 min,31 min and 41 min after runoff initiation,respectively.The total runoff amount decreased in the order of 0%straw mulching>100%straw mulching>50%straw mulching(P<0.05),and in the order of 0%straw mulching>50%straw mulching>100%straw mulching(P<0.01)under rainfall intensities of 60 and 90 mm/h,respectively.When the rainfall intensity was 60 mm/h,50%rice straw mulch reduced the soil erosion by 73.46%compared to bare soil without mulching,and 100%rice straw mulch delayed the runoff initiation time by 84.53%.When the rainfall intensity was 90 mm/h,the reduction rates of the soil erosion induced by 50%and 100%rice straw mulch were 54.83%and 72.14%,respectively.The results indicated that straw mulching measures effectively reduced the runoff and sediment yields of the soil slopes in the mining area.