Survey of geological hazards by RS and the spatial distribution characteristics in Yanchi county

Yanchi county in the Ningxia Autonomous Region lies in the Loess Plateau, where ecological environment is weak and severe geological hazards frequently occur. Based on the RS data such as SPOT6, RapidEye, LandSat8 OLI and UAV, 125 landslides, 84 collapses, 19 debris-flows and 3 surface collapses are interpreted by examining the RS image characteristics and by building interpretation indication of geological hazards. According to regional geographical and geological environmental characteristics, the basic features of the geological hazard points are summarized. Seven concentrated distribution regions are divided and the spatial distribution characteristics of geological hazard points are characterized on the basis of the point density analysis by employing the GIS technology. This paper uses the spatial analysis function of GIS to discuss the relationship between the geological hazard spatial distribution and vegetation and topography. The results show that geological hazard points in the study area are characterized by small size, low hazard and such threat objects as village, farmland and country roads. Point density is high in the south and low in the north, suggesting that the hazard points are concentrated in the south and dispersed in the north, and the concentrated region is located in Mahuangshan-Xuejiapan. The strata, vegetation, slope and aspect are related to geological hazards.