按照制定的土壤侵蚀图成图系列，根据黄土丘陵沟壑区的特点，以地形结构特征图为主要控制，按地形一植被条件（或土地利用）一致性原则圈定图斑，用多层逐步判别归类法确定土壤侵蚀的相对等级，再运用试错迭代法并参照各小流域的实测土壤侵蚀资料把土壤侵蚀分级图转化为定量的土壤侵蚀强度图，完成了洪水沟流域的侵蚀等级的地面绝对定标，得到反映各侵蚀因子综合作用的且有充分的地面侵蚀实测数据支持的士壤侵蚀强度分布图。 According to the developed series of maps of soil erosion, according to the characteristics of loess hilly and gully area, the topographic structure map is taken as the main control, and the map is made according to the consistency of topography and vegetation condition (or land use) Class method to determine the relative level of soil erosion, and then use trial-and-error iteration method with reference to the measured soil erosion data of small watershed soil erosion classification map into a quantitative soil erosion intensity map to complete the erosion level of the flood ditch valley ground absolute Calibration, get the erosion of soil erosion intensity distribution map that reflects the comprehensive effect of each erosion factor and has sufficient ground erosion data.