水力梯度影响下WEPP模型估计细沟侵蚀参数的可行性分析

发布时间：2018-06-29 06:03

  本文选题：侵蚀 + 径流　； 参考：《农业工程学报》2017年08期

【摘要】：为分析近地表水文条件影响下WEPP(Water Erosion Prediction Project)模型估计细沟可蚀性和临界剪切力的可行性,该研究选取长江中上游地区典型黄壤为研究对象,采用不同水力梯度值模拟饱和/渗流(水力梯度为0、0.71和1.43 m/m)和排水(水力梯度为?0.71和?1.43 m/m)2种近地表水文条件,并设置3个放水流量(0.55、1.58、2.51 L/min),利用"V"形试验土槽测定不同条件下细沟产流产沙,以WEPP模型估算的土壤可蚀性和临界剪切力为计算值。测定增大流量直到侵蚀开始并出现连续不断的土壤颗粒分离时所对应的流量,将基于此流量计算获得的临界剪切力作为实测值。比较临界剪切力计算值与实测值验证WEPP模型估算的可靠性。结果表明,在饱和/渗流条件下,土壤剥蚀率随着冲刷历时的增加逐渐减小;在排水条件下,放水流量为0.55 L/min的土壤剥蚀率随冲刷历时的增加快速减少并逐步稳定,而随着放水流量增大土壤剥蚀率波动的更为剧烈。5个水力梯度平均细沟可蚀性为2.51×10?2 s/m。饱和/渗流条件下细沟可蚀性为3.07×10?2 s/m,是排水条件的1.78倍。除水力梯度为?1.43 m/m时临界剪切力在WEPP模型中的计算值与实测值相符外,在?0.71~1.43 m/m范围内,临界剪切力的计算值均高估了实测值,平均高估了36.85%。临界剪切力实测值与计算值呈指数函数关系(R2=0.77,P0.01)。该研究可为黄壤的侵蚀防治及WEPP细沟侵蚀模型临界剪切力修正提供理论支持和科学指导。
[Abstract]:In order to analyze the feasibility of estimating the erodibility and critical shear stress of rill by WEPP (Water erosion Prediction Project) model under the influence of near-surface hydrological conditions, the typical yellow soil in the upper and middle reaches of the Yangtze River was selected as the research object. Two kinds of near-surface hydrological conditions are simulated by using different hydraulic gradient values (hydraulic gradient 0 0. 71 and 1. 43 m / m) and drainage (hydraulic gradient 0. 71 and 1. 43 m / m). At the same time, three water discharge rates (0.555 ~ 1.58 ~ 2.51 L / min) were used to measure sediment yield under different conditions. The soil erodibility and critical shear force estimated by WEPP model were calculated. The critical shear force calculated on the basis of the increasing flow rate until the erosion begins and the continuous soil particle separation occurs is taken as the measured value. The reliability of the WEPP model is verified by comparing the critical shear force calculation values with the measured values. The results showed that the soil erosion rate decreased gradually with the increase of erosion duration under saturated / percolation condition, and decreased rapidly with the increase of erosion duration when the discharge rate was 0.55 L / min. The erosion rate fluctuated more sharply with the increase of water discharge. The erodibility of the five hydraulic gradients was 2.51 脳 10 ~ (2) s / m. The erodibility of the rill under saturated / percolation is 3.07 脳 10 ~ (2) s / m, which is 1.78 times as much as the drainage condition. Except when the hydraulic gradient is 1.43 m / m, the calculated value of critical shear force in WEPP model is in agreement with the measured value. In the range of 0.71 ~ 1.43 m / m, the calculated value of critical shear force overestimates the measured value and the average value is 36.85%. The experimental value of critical shear force is exponentially related to the calculated value (R2 / 0.77 / P0.01). This study can provide theoretical support and scientific guidance for erosion control of yellow soil and revision of critical shear force of WEPP rill erosion model.
【作者单位】： 北京林业大学水土保持学院;北京林业大学重庆缙云山三峡库区森林生态系统国家定位观测研究站;
【基金】：北京高等学校青年英才计划资助(YETP0751) 国家自然科学基金项目(41401299)
【分类号】：S157.1
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本文编号：2081145