人工模拟降雨供水水质对坡面产流产沙的影响

Effects of Water Quality on Runoff and Sediment Yield in Rainfall Simulation

利用黄土高原2种典型的土壤类型(黄土和塿土),在2个降雨强度(45.5,95.5mm/h)和2个坡度(8.7%,25.9%)条件下进行了人工模拟降雨试验,研究了3种水质(去离子水、自来水、盐水)对坡面产流、产沙过程的影响。结果表明,2种土壤类型的产流过程差异显著,黄土条件下去离子水最先产流,但产流速率小于自来水与盐水;而塿土条件下去离子水的产流速率始终最大,自来水与盐水由于离子数量相当,产流速率差异较小。水质主要通过地表结皮的形成与发育影响径流,以总降水量45.5mm为例,径流深随供水电导率的增大而减少,与去离子水相比,黄土条件下自来水和盐水的径流分别减少了5.7 mm和1.5mm,而塿土条件下分别减少了7.2mm和9.8mm。受产流过程的影响,不同供水水质条件下产沙过程不一,产沙速率与产流速率变化同步。2种土质条件下产沙量均是去离子水最大,与去离子水相比,自来水和盐水分别减少了45.9%,35.8%(黄土)和65.6%,68.3%(塿土),结果显示模拟降雨水质会显著影响坡面产流产沙过程,为保证试验数据的准确性和可对比性,建议在进行人工降雨相关试验时均采用去离子水。

2typical soil in the Loess Plateau（Loess and Lou soil）,2different rainfall intensities（45.5mm/h and 95.5mm/h）and 2slope gradients（8.7% and 25.9%）were used to qualify the impact of 3water quality（deionized,tap and saline water）on runoff and soil erosion in rainfall simulation.The results showed that the runoff rate acted differently between 2types of soil.Tap water and saline water delayed the time of runoff yielding,but the runoff rate of deionized water grew more slowly than tap water and saline water under Loess.For Lou soil,deionized water always showed the highest runoff rate,while tap water and saline water were similar in salinity,and did not differ in runoff rate.Water quality influenced the runoff indirectly by the formation and development of crust.When precipitation was 45.5mm,runoff amount significantly decreased with the increasing electrical conductivity,tap and saline rainwater decreased runoff depth by 5.7 mm and1.5mm for Loess,and by 7.2 mm and 9.8 mm for Lou soil,compared with deionized rainwater.The sediment yielding rate had significantly difference under different rainwater conditions and it was closely related to the runoff rate.Deionized water had a maximum sediment yield,while tap and saline rainwater decreased runoff depth by 45.9% and 35.8% for Loess,and by 65.6% and 68.3% for Lou.It should be noted that runoff and erosion were significantly affected by the quality of water in simulated rainfall.Therefore,deionized water was recommended for rainfall simulation to improve the accuracy and comparability of results.