GIS Based Landslide Hazard Zonation Mapping (LHZM) for Rattota DS Division, Matale District, Sri Lanka

Landslides have become the most significant disaster and frequent phenomenon in Central Highland of Sri Lanka in recent decades. And also, the recent landslides have brought intense impacts to the communities living in landslide prone areas of Rattota, in Matale District. Thus, preparation of Landslide Hazard Zonation Maps (LHZ) has become an essential tool in the landslide risk reduction especially in this area. This study has been mainly focused on producing LHZ map as the beneficial to community as well as the relevant institutions. The LHZ map was prepared for the selected 8 GN Divisions from Rattota DS Division, based on the influence of different causative factors. These causative factors, including geology, landforms, land use, slope gradient, past landslide locations, and drainage density were considered for the generation of LHZ map. The data for the generation of LHZ map were obtained from several sources and then were integrated using GIS to the demonstration of map. GIS based bivariate statistical approach (Weighted Overlay Model) was adopted in this study. The map delineated the unstable hazard-prone areas in the study location. Based on the results from the hazard map, different levels were identified as follows, very high hazard, high hazard, moderate hazard, low hazard, and very low hazard. Most part of the study area was belonged to moderate to high hazard area. Very high hazard areas, and low hazard areas were found at lower level. High hazard areas of landslides widely existed in Bambarakiriella, Madakumbura, and Bodhikotuwa GN Divisions. Subsequently, Horagolla, Mousagolla and Welangahawatta Divisions were also resulted as high hazard with the lowest proportion. Accordingly, these results clearly emphasize that hazard level varied from division to division and some zones in the study area potentially dangerous for further development of habitation. There must be immediate implementation of proper mitigation works in the high hazard zones like Bodhikotuwa Division. Accordingly, effective utilization of this map would considerably reduce the damage potential and also facilitate the planning process in the study area.