Landslide susceptibility mapping and hotspot analysis using the analytical hierarchy process in the Teesta River Basin

Abstract

Landslides happen often and cause serious problems in the Teesta River Basin, threatening buildings, communities, and the environment. This study uses a mapping system called GIS combined with a decision-making method called AHP to evaluate where landslides are likely by combining different types of information into a risk map. The AHP method gives importance to ten factors that affect landslides: slope, rainfall, shape of the land, distance from roads, distance from streams, vegetation health (NDVI), stream power (SPI), direction the land faces, land use, and geology. Several spatial tests, like Nearest Neighbour Analysis, Moran’s I, and hotspot analysis, are used to study how landslide areas are spread out. The model’s accuracy is checked using a test called the ROC curve. The results show that slope, rainfall, and land shape are the most important factors, while land use and geology have less effect. The risk map divides the area into five zones: very low, low, moderate, high, and very high risk. About 18.6% and 7% of the area fall into high and very high risk zones, mostly in the south and west, where landslides often happen on steep slopes, high places, heavy rain, and little vegetation. The very low risk zone covers 36.8% of the area, and the moderate zone covers 18.3%. Targeted safety measures are needed in the high-risk zones. More than 63% of the area is in the low-risk category. The spatial tests confirm that landslides cluster in high-risk areas, shown by Moran’s Index (0.77) and Nearest Neighbour Analysis (0.30). Hotspot analysis points out exact high-risk spots, and the ROC test shows the model predicts landslides fairly well with a score of 0.71. These results offer useful information for managing landslide risks and planning infrastructure in the Teesta River Basin.