雨强和坡度对铁尾矿砂坡面复垦前后产流产沙的影响

Effects of Rainfall Intensity and Slope Gradient on Runoff and Sediment Production on the Slope Before and After Reclamation in Iron Tailings

运用人工模拟降雨技术,研究铁尾矿砂裸坡及复垦坡面在雨强和坡度共同作用下的产流产沙特征。结果表明:(1)坡面产流及产沙受各因子影响程度均为:雨强>坡度>基质类型。(2)就铁尾矿砂裸坡而言,雨强对坡面产流影响显著,坡面产流随着雨强和坡度的增大均呈现递增趋势,随着雨强的增大,其作为坡面产流主导因素的作用突显,会出现掩盖坡度对坡面产流影响的现象;坡面产沙随着雨强的增大基本呈现递增趋势,且坡度越大产沙的增幅越大,雨强和坡度对坡面产沙影响均显著。(3)在复垦设计坡度25°条件下,就减流效果而言,不同基质类型复垦坡面间减流规律相似、效果差别甚微,随着雨强的增大减流效果逐渐消失;单纯考虑减沙效果,不同复垦坡面的减沙效果因基质的不同存在一定的差异,综合考虑不同雨强下的减沙效果,铁尾矿砂与菌糠混合物是复垦坡面基质的最优选择。研究结果可为铁尾矿砂裸坡土壤侵蚀的防治和铁尾矿库复垦提供经验参考和合理建议。

The rainfall simulation technique was applied to study the characteristics of runoff and sediment yield under the combination of rain intensity and slope on slope before and after reclamation in the iron tailings.The results showed that:(1)the influence of various factors on runoff and sediment yield on slope decreased in the order:rainfall intensity >slope gradient >substrate type;(2)in the case of bare slopes of iron tailings,rainfall intensity significantly affected runoff on the slope,and the runoff presented the increasing trend with the increase of rainfall intensity and slope gradient;as the rainfall intensity increased,its role as the dominant factor of slope runoff was prominent,and the phenomenon covering the effect of slope gradient on the runoff occurred;the sediment yield increased with the increase of rainfall intensity,the increase of sediment yield became larger when the slope gradient was greater,the influences of rainfall intensity and slope gradient on the sediment yield were significant;(3)under the condition of designed reclamation slope with 25°,in terms of the effect of runoff reduction,the patterns of runoff reduction among different substrates were similar,and the effects were little different;with the increase of rainfall intensity,the effect of runoff reduction gradually disappeared;considering the effect of sediment reduction only,the effects of sediment reduction on different reclamation slopes were different because of the different substrates;with respect to comprehensive consideration of sediment reduction effects under different rainfall intensities,it was the best choice to use the mixture of iron tailings and mushroom residues as the substrate for slope reclamation.The results can provide empirical references and reasonable suggestions for the prevention and control on erosion on bare iron tailing slope and the reclamation of iron tailing pond.