Assessing Terrain Stability in a GIS using SINMAP
SINMAP (Stability Index MAPping) is an ArcView GIS extension that facilitates the assessment of landslide potential at the watershed scale. SINMAP has as its theoretical basis the infinite plane slope stability model. Digital elevation model (DEM) methods are used to estimate the slope of the terrain as well as the potential soil moisture conditions as influenced by topographic flow convergence. Other parameters considered include soil friction & transmissivity, root cohesion, and water recharge. Some parameters may be uncertain and can therefore be characterized by uniform distributions between specified limits. These may be adjusted and calibrated for geographic strata based upon soil, vegetation or geologic data. The software enables an interactive visual calibration that adjusts parameters while referring to observed landslide distributions. Parameters can be adjusted so that the resulting stability map “captures” a high proportion of observed landslides in regions with low stability index, while minimizing the extent of low stability regions and consequent alienation of terrain to regions where landslides have not been observed. SINMAP is implemented as a software extension to the ArcView GIS from Environmental Systems Research Institute, Inc.