坡面径流侵蚀产沙动力机制比较研究

Comparisons of Dynamic Meachanics of Soil Erosion and Sediment Yield by Runoff on Loess Slope

分别利用坡面径流剪切力、坡面径流能耗和坡面径流单位水流功率理论对坡面土壤侵蚀发生过程进行了研究。研究结果表明,坡面径流平均输沙率与坡面径流平均剪切力之间均存在明显的线性关系,试验的土壤抗蚀性参数为178 5g/(Pa·min),径流临界剪切力为0 54Pa。根据径流能耗理论的计算结果表明,径流单宽输沙率和单宽径流能耗之间具有如下的线性关系式:Dr=14 61(ΔE-0 37),表明试验的土壤可蚀性参数为14 61g/J,临界单宽径流能耗为0 37J/(min·cm)。根据径流功率理论的计算结果,坡面径流功率与径流平均输沙率之间存在比较明显的线性关系,随着径流功率的增加,坡面径流输沙量明显增加,二者的线性关系为:Y=8942 2x-68 676。总体来说,3种理论在土壤侵蚀研究中的应用各有优势,其中坡面径流能耗理论相对简便并且误差较小,更利于对坡面土壤侵蚀过程进行描述。

In this research, soil erosion and sediment yield was calculated by runoff shear stress, runoff energy consumption and runoff power theory respectively. Results indicated that linear relationship was existed between average runoff shear stress and sediment yield, soil erodibility in the experiment was 178.5g/(Pa·min), and the critical shear stress value was 0.54 Pa. Results by energy consumption implied that there was also linear relation between sediment transportation and energy consumption of unit runoff width: Dr=14.61(ΔE-0.37), which indicated that soil erodibility was 14.61 g/J, with critical energy consumption of 0.37 J/(min·cm). Results by runoff power theory showed that sediment transportation increased with the increase of runoff power, and simple linear relation was also regressed: Y=8942.2x-68.676. Generally, these three theories showed its advantage in describing soil erosion process on slope, among which results from energy consumption theory was simpler and more accurate, and was more convenient in describing soil erosion on slope.