Because change of volume reflected eroding process of watershed and surface change reflected change of topography surface, this model described relationship between watershed topograph and erosion.

• 由于相对体积变化反映了流域遭受侵蚀的过程，而表面积变化体现的是地形表面的变化，因而此关系模型同时表述了流域地形与侵蚀之间的关系。