Abstract

Hillslopes of the catchments in nature have three forms (convergent, divergent, parallel) in terms of plan shape and also in terms of floor curvature profile, they have three convex, concave, and straight shapes combining into complex hillslopes. Previous studies indicated the topography and geometry of complex hillslopes influence their hydrologic responses/attributes in both surface and subsurface flow. The three-dimensional shape and geometry of the hillslopes were introduced into Topmodel as the new parameters, and a complex Topmodel was presented that could check the saturation of different parts of complex hillslopes. The complex Topmodel model was linked to the landslide model “SINMAP”. Finally, the spatial–temporal variations of the saturation of the complex hillslopes and their stability rate were investigated using the Dynamic Topmodel. Results revealed that the influence of local slope, which is a function of curvature of the hillslopes, is more dominant than the saturation rate on the stability of the hillslopes. In contrast with convex hillslopes, the downstream in the concave hillslopes was more stable than upstream. Nevertheless, the upstream area in the concave hillslopes and downstream in the convex ones can be prioritized to implement artificial stabilization.