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在降雨条件下,对土壤侵蚀起作用的两个主要过程是降雨分散和径流冲刷。对于两种供试土壤,通常是坡度最陡径流含沙量(c)就最大,且c随坡度的降低而减少。在连续降雨和(或)径流条件下,c通常是随时间的推移而下降,最后达到平衡。在平衡条件下,土壤流失赖以产生的降雨分散和径流冲刷的相对重要性,取决于土壤类型和由坡度与水流共同作用产生的流动势。在黑土的流动势<0.1 W m~(-2)、盐土的<0.3W m~(-2)时,对c起最大作用的是降雨分散;而在较大的流动势时,对c起主要作用的是径流冲刷。在任何流动势下,降雨对结构脆弱的盐土的分散作用都大于对有良好团聚体结构的黑土。在流动势较低时,两个侵蚀过程相互作用所产生的c高于两者单独作用所产生的含沙量的总和。当流动势约高于0.5W m~(-2)时,降雨会抑制细沟发育而减少侵蚀产生的含沙量。 研究结果表明,径流冲刷和降雨分散可以从细沟间区域获得含沙量。
Under rainfall conditions, the two main processes that contribute to soil erosion are rainfall dispersion and runoff scouring. For both tested soils, it is usually the steepest runoff sediment concentration (c) that is greatest and c decreases with decreasing slope. Under continuous rainfall and / or runoff conditions, c usually declines over time and eventually reaches equilibrium. Under balanced conditions, the relative importance of rainfall dispersion and runoff scouring due to soil loss depends on the type of soil and the flow potential created by the combined effect of slope and water flow. When the flow potential of black soil is less than 0.1 W m -2 and the soil salt is less than 0.3 W m -2, the precipitation is the most important for c, while for a large flow potential, The main role is runoff erosion. Under any flow potential, precipitation is more diffusive to structurally weaker saline soils than to black soil with good aggregated structure. At low flow potential, the interaction between the two erosion processes produces higher c than the sum of the sediments produced by the two actions alone. When the flow potential is higher than 0.5W m -2, the rainfall will restrain the development of the rills and reduce the sediment concentration caused by erosion. The results show that runoff scouring and rainfall dispersal can obtain the sediment concentration from the area between the slender.