断面法测量切沟体积精度分析

Accuracy Analysis of Section Method for Measuring Gully Volume

以吴起县退耕还林森林公园合沟小流域为研究区,选择11条典型切沟,借助激光测距仪、塔尺等工具,分别采用均匀间距断面法和非均匀间距断面法确定断面位置,测量断面形态参数,对比2种测量方法下切沟形态特征的差异;以3D激光扫描数据为基准,比较2种断面法测算切沟体积的精度,最后分析不同数据源对构建切沟体积估算模型的影响。结果表明:研究区切沟形状大多为V~U形,以非均匀间距断面法测量体积的相对误差略小于均匀间距断面法。实地测量时,断面形状呈U形的切沟,采用均匀间距断面法测算体积更为准确;断面形状呈V形的切沟,适宜采用非均匀间距断面法;断面形状呈V~U形时,若顶宽从沟头到沟口变化较大时,适宜采用非均匀间距断面法,当变化较小时适宜采用均匀间距断面法测算切沟体积。对研究区内切沟体积进行估算时,建议采用最适宜断面法测量的切沟面积(A)与体积(V)建立模型。该研究结果可为断面法准确测量切沟体积提供科学依据。

11 typical gullies were selected in Hegou watershed of the Forest Park in Wuqi County to determine the position of the section by using the uniform spacing section method and non-uniform spacing section method and measure the morphological parameters of the section with the help of tools such as laser rangefinder and tower ruler.The morphology characteristics differences of gully between the two measurement methods were compared.Using 3D laser scanning data as a benchmark,the accuracy of the two section methods to measure the gully volume were compared,and the influences of different data sources on the construction of the estimation model of the gully volume were finally analyzed.The results showed that most of the gullies in the area were V-U-shaped,and the volume’s relative error measured by the non-uniform spacing section method was slightly smaller than the relative error of the uniform section method.When measured in the field,for gullies of the section with U-shaped,the uniform spacing section method was more accurate to measure the volume.The non-uniform spacing section method was more suitable for V-shaped gullies.When the section shape was V-U,if the top width of gully changed greatly,the non-uniform spacing section method was appropriate.When the change was small,the uniform spacing section method was used to measure the gully volume.When estimating the gully volume in the area,it was recommended to use the area(A)and volume(V)of the gully measured by the most suitable section method to establish the model.The results of this study could provide the scientific basis for the accurate measurement of the gully volume by the section method.