WEPP模型（坡面版）在紫色土区域高速公路边坡水土流失中的应用

发布时间：2018-01-21 09:24

本文关键词： 紫色土高速公路边坡 WEPP 水土流失　出处：《重庆大学》2015年硕士论文　论文类型：学位论文

【摘要】：土壤侵蚀预报模型的研究能够为水土保持监测点的布设以及水土保持方案制定和实施提供强有力的科学支撑。水蚀预测模型WEPP作为一种基于侵蚀过程的模型,是可以对土壤水蚀有关的过程进行具体、全面描述的程序,但目前WEPP模型在国内紫色土区域边坡的应用还较少,因此开展适合于紫色土区域高速公路边坡的侵蚀预报模型研究具有现实意义。本文基于水蚀预报模型WEPP坡面版,对紫色土区域高速公路边坡在降雨作用下的水土流失情况进行了研究,并利用模型有效性ME(Nash-Sutcliffe Model Efficiency)对该模型在紫色土区域的适用性进行了评价。最终将WEPP模型坡面版应用于梁平至忠县高速公路在建项目中,对径流量和产沙量进行预测,为水土流失监测点的布设和水土保持措施的制定提供参考。本研究的主要内容与成果包括:①开展土壤粒径分析、有机质测定、阳离子交换量测定等土壤参数的测定实验,得到紫色土区域梁平至忠县段紫色土壤的基本参数,土壤样品的石粒、砂粒、粉粒、粘粒百分比分别为5.70%、34.21%、56.73%、3.36%,有机质含量为2.448%,CEC为13.30meq/100g,通过公式计算得到WEPP模型运行所需的土壤模块参数:反照率为0.59,初始饱和度为52.25%,细沟侵蚀参数为0.0144s/m,临界剪切力为0.5683 Pa,有效水力传导系数6.3461 mm/l。②建立了运行WEPP模型所需要的气候文件、土壤文件、坡面文件及作物管理文件。以万州水土保持监测站15°边坡的径流小区20次降雨侵蚀的实测数据为基础,利用WEPP模型(坡面版)对紫色土区域15°坡度条件下裸露坡面次径流量、侵蚀量及多年径流量、侵蚀量分别进行了预测,坡面的径流量、产沙量的预测值与实测值的差异很小,基本分布在趋势线y=x两侧,径流结果的相对误差小于30%的占80.95%,产沙结果的相对误差小于30%的占42.84%,并利用模型有效性ME(Nash-Sutcliffe Model Efficiency)对模型在紫色土区域的适用性进行了评价,径流量、产沙量对应的模型有效性ME分别为0.9288、0.7862。可见,在预测紫色土休闲小区单次降雨产沙量时,WEPP模型的模拟精度要低于对径流量的模拟精度,但预测值与实测值仍能呈现出相同的变化趋势,能够在一定程度上反映单次降雨对径流小区造成的侵蚀作用。WEPP模型坡面版在紫色土区域具有一定的适用性。③利用WEPP模型对不同坡度、管理方式下坡面的单次径流量、单次产沙量以及多年径流量、多年产沙量进行预测,并对径流量、产沙量随坡度的变化规律进行分析。在单次降雨过程的参数保持不变的条件下,坡度对径流量影响不大。产沙量随坡度的增加呈现先增大后减小的变化趋势,临界坡度为55°,在15°~55°间产沙量逐渐增大,55°~70°间产沙量逐渐减少。产沙量增幅排序为:R5,10R10,15R15,20……R65,70。另外,坡面植被能够降低降雨对坡面的直接溅蚀,缓冲绿化带对径流携带的土壤颗粒有拦截作用,从而减小径流量和产沙量,起到水土保持的作用。对降雨过程的参数进行敏感性分析,得到敏感性排序:降雨量最大雨强降雨历时达到最大雨强的时间与降水总历时的比率(TP)。④将WEPP模型应用于梁平至忠县高速公路在建项目的50个边坡中,对各边坡水土流失预测,模拟结果显示,坡面XP29、XP35、XP44、XP50的径流量和产沙量均处于较高水平,应在施工过程中对其进行重点监测和防护,为水土流失监测点的布设、水土保持措施的制定提供参考。
[Abstract]:Study on soil erosion prediction model for layout of monitoring points and soil and water conservation plan and provide strong scientific support for the implementation of soil and water conservation. The water erosion prediction model WEPP as an erosion process model based on soil erosion can be associated with specific process, the comprehensive description of the program, but the application of WEPP model in China the purple soil slope area is less, so it has practical significance to research the erosion prediction model suitable for the purple soil region of highway slope. This slope water erosion prediction model based on WEPP version, in the effect of rainfall on Soil and water erosion in purple soil area of highway slope is studied, and the validity of the model by using ME (Nash-Sutcliffe Model Efficiency) evaluation of the applicability of the model in the purple soil area. The final version of the application of the WEPP model on Yu Liangping Zhi Zhong County highway construction projects, to forecast the runoff and sediment yield, soil erosion monitoring points and measures of soil and water conservation for reference. The main content of this research and achievements include: the soil particle size analysis, determination of organic matter, the experimental determination of cation exchange capacity and determination of soil parameters. The basic parameters of the purple soil region to Zhongxian Liangping purple soil, soil stone, sand, silt and clay percentages were 5.70%, 34.21%, 56.73%, 3.36%, organic matter content is 2.448%, CEC is 13.30meq/ 100g, the soil module parameters required to run the WEPP model by formula: albedo 0.59, the initial saturation is 52.25%, rill erosion parameter is 0.0144s/m, the critical shear stress for 0.5683 Pa, the effective hydraulic conductivity of 6.3461 mm/l. was established to run WEPP model to the soil climate file. A slope, documents and crop management documents. In Wanzhou soil and water conservation monitoring station runoff 15 degrees slope rainfall erosion 20 measured data as the basis, using the WEPP model (Hillslope Version) of the purple soil region 15 degrees slope under a bare slope runoff, erosion and runoff erosion years, respectively. The prediction of runoff, slope, sediment yield prediction value and the measured value of the difference is very small, the basic distribution on both sides of the trend line at y=x, the relative error of runoff results less than 30% accounted for 80.95% of the sediment and the relative error is less than 30% accounted for 42.84%, and the use of ME (Nash-Sutcliffe Model Efficiency model is valid) evaluation of the applicability of the model in the purple soil area of runoff, the effectiveness of the ME model corresponding to the sediment yield were 0.9288,0.7862. visible, in the prediction of purple soil fallow plot single rainfall sediment yield, simulation model of WEPP Is less than the simulation accuracy of runoff prediction, but still showed the same trend with the measured value, to a certain extent, reflect the rainfall caused by the runoff erosion on Hillslope Version.WEPP model has some applicability in the purple soil area. Using the WEPP model for different slope management the way downhill single single runoff, sediment yield and runoff for many years, years of sediment yield prediction, and the runoff and sediment variation of slope were analyzed. The same parameters in single rainfall, slope runoff on sediment yield is not affected. Increased first and then decreased with the increase of slope, critical slope of 55 degrees, gradually increased in the sediment yield of 15 ~55 degrees, the sediment yield of 55 degrees ~70 degrees gradually decreased. The sediment yield increase order: R5,10R10,15R15,20.R65,70. and slope The surface vegetation can reduce the rainfall on the slope of the direct splash, buffer green belts interception effect on soil particles in runoff, and runoff and sediment, play the function of soil and water conservation. The sensitivity analysis of the parameters of the rainfall process, get the sensitivity of sorting: rainfall maximum rainfall duration reached maximum rain rate the time and the total duration of precipitation (TP). The 50 slope WEPP model applied to Liangping Zhongxian Expressway in construction project, to predict the slope soil erosion, the simulation results show that the slope of XP29, XP35, XP44, XP50 of the runoff and sediment yield were at a high level, should be carried out focus on monitoring and protection of the construction process, soil erosion monitoring layout, soil and water conservation measures provide a reference.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.14;S157

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