近地表土壤水分条件对坡面土壤侵蚀过程的影响

 采用人工模拟降雨实验,研究近地表土壤水分条件对安塞黄绵土和杨陵塿土土壤侵蚀过程的影响,尤其是土壤水分饱和条件下的土壤侵蚀过程。结果表明:土壤质地对入渗和径流过程有较大影响。对同一质地的供试土壤,随着前期近地表土壤含水量的增大,入渗量减少,而径流强度增大,坡面初始发生产流时间也越早。当前期近地表土壤含水量相近时,杨陵塿土的初始产流时间早于安塞黄绵土,坡面径流量和侵蚀产沙量也随前期近地表土壤水分含量的增加而增大。对于安塞黄绵土,当前期土壤含水量分别为饱和含水量的100%、75%和50%时,其径流量分别占饱和含水量的25%时的2.5、2.2和1.3倍,其侵蚀产沙量分别为50、25和1.3倍。而对于供试土壤为杨陵塿土,当前期土壤含水量分别为饱和土壤含水量的100%和50%时,其径流量分别是占饱和土壤含水量的25%时的1.1和1.0倍,其侵蚀产沙量分别为6.5和2.0倍。在降雨过程中,前期土壤含水量越大,片蚀发展为细沟侵蚀的时间越早,而且细沟侵蚀也越严重。

Effects of near-surface soil water conditions on soil erosion process

In this paper the effects of near-surface soil water conditions on soil erosion was studied, especially for water saturated soil, using rainfall simulation experiment. The results showed that difference of soil texture had great effects on soil infiltration, and runoff process. Under the same soil texture, as antecedent soil moisture increased, infiltration rate decreased and runoff intensity increased. With the increase of antecedent soil water content, the time of runoff occurrence brought forward, runoff discharge and soil loss increased. For Ansai Loess soil, runoff discharge from soil moisture saturated condition, 75 % of the saturated condition of soil moisture, and 50% of the saturated condition of soil moisture were 2.5, 2.2, and 1.3 times higher respectively, than that from 25 % of the saturated condition of soil moisture. As compared to 25 % of the saturated condition of soil of soil moisture, and moisture, soil loss from soil moisture saturated condition, 75 % of the saturated condition 50% of the saturated condition of soil moisture were 50, 25, and 1.3 times greater, respectively. For Yangling Loutu soil, runoff discharge from soil moisture saturated condition and 50% of the saturated condition of soil moisture were 1.1 and 1.0 times higher, than that from 25 % of the saturated condition of soil moisture. As compared to 25 % of the saturated condition of soil moisture, soil loss from soil moisture saturated condition and 50% of the saturated condition of soil moisture were 6.5 and 2.0 times greater, respectively. During rainfall process, as antecedent soil moisture increased, the time of rill erosion occurrence was earlier and rill erosion increased.