Comparative factors that influence landslide occurrence: application of gis and rainfall thresholds in landslide assessment in kenya

Abstract

Landslides are recurrent phenomena in Murang’a and Mt. Elgon Districts, causing loss of lives, property and fertile farmland. Despite the grievous danger posed, comparative studies of landslides in the two districts have neither been carried out nor has the use of state-of-the-art methods of landslide risk assessment been applied. In this review paper, the factors influencing the occurrence of landslides in Murang’a and Mt. Elgon Districts have been comparatively studied in order to review how these factors influence landslide occurrence. The four factors discussed in depth include geology, topography, rainfall distribution, and soil-sediment characteristics. In the two districts, the four factors play relatively a similar role as far as landslide occurrence is concerned. Therefore, such comparative studies can be used to predict landslide vulnerability in different areas. Two major techniques of landslide hazard assessment that is, application of GIS and rainfall thresholds, have been reviewed with an aim of boosting landslide research in the two districts. In the application of GIS in landslide assessment, creation of a standard GIS landslide database has been carried out in accordance with some successful GIS databases in the world. The database has been used to construct various landslide vulnerability maps for both Murang’a and Mt Elgon Districts. A comprehensive review of landslide assessment using rainfall thresholds has been carried out. However, this method cannot be accurately applied in the two districts due to limitations of rainfall data (hourly rainfall data) due to lack of relevant instruments such as pluviometers.