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在流域水文学研究与应用领域中 ,坡面水流占有十分重要的地位 ,但如何获取坡面水流的有效糙率是至关重要的一步。本文针对林地地表径流运动的形成过程和运动特点 ,建立了林地渗透坡面地表径流运动基本方程 ,通过讨论土壤水分运动和地表径流运动参数 ,将土壤水分运动简化为一维Smith Parlange模型 ,地表径流简化为运动波模型 ,采用一步Lax Wendroff有限差分格式进行数值模拟 ,以最小离差平方和为目标函数 ,通过叠代计算获取林地地表径流的有效糙率。根据人工模拟降雨地表径流过程实测资料计算了油松林、刺槐林、蒙古栎林 3种林分的有效糙率 ,计算结果表明 ,2 2a生刺槐林地的最大 ,在 0 1 93 1～ 0 2 1 3 1之间 ;其次为 3 0a生蒙古栎林地 ,为 0 1 70 1 ;2 0a生油松林地为 0 1 42 3。从参数寻优的结果来看 ,m值在2 76～ 3 0 90之间 ,接近层流时的m =3。为检验模型和参数的可靠性 ,用计算获得的林地坡面径流过程线与实测径流过程线进行了比较 ,结果表明采用此模型和数值模拟方法可以很好地模拟渗透坡面林地地表径流运动。
In the field of basin hydrology research and application, the slope water plays a very important role, but how to get the effective roughness of water flow is a crucial step. In this paper, based on the formation process and movement characteristics of the surface runoff in forest land, the basic equation of surface runoff on the slope surface is established. By discussing the parameters of soil moisture movement and surface runoff, the soil moisture movement is reduced to one-dimensional Smith Parlange model. The Lax Wendroff finite difference scheme is used to simulate the moving wave model. The objective function of the sum of squares of minimum deviations is used to obtain the effective roughness of surface runoff from the forest by iterative calculation. The effective roughness of three stands of Pinus tabulaeformis, Robinia pseudoacacia and Quercus mongolica forest was calculated based on the measured data of surface runoff simulated by artificial rainfall. The calculated results showed that the maximum value of woodland of 2 2 acacia locusts ranged from 0 1 93 1 to 0 2 1 3 1, followed by 30 years of Quercus mongolica forest land, 0 1 70 1; and 0 0 a Pinus tabulaeformis forest land 0 1 42 3. From the results of parameter optimization, m is between 76 and 30090, and close to the laminar flow m = 3. In order to test the reliability of the model and the parameters, the runoff curves of the runoff on the slope surface and the measured runoff curves were compared. The results show that this model and the numerical simulation method can simulate the surface runoff on the slope surface.