Application of Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) in flood hazard analysis in the Rawa Pening Sub-Watershed, Indonesia

Abstract

The watershed is one of the ecological functional units in a region. The Rawa Pening Sub-Watershed, located in Semarang Regency and its surroundings, is the upper region of the Tuntang Watershed, which experiences periodic floods. Flood hazard disasters occur due to several contributing factors. This phenomenon significantly affects the residents in the Rawa Pening Sub-Watershed, particularly in the agricultural sector, specifically in the local paddy fields. With the development of Geographic Information Systems (GIS) in disaster management, it is possible to provide preliminary information on predicting flood hazard zones, particularly in the Rawa Pening Sub-Watershed. This study aimed to determine the most influential parameters and areas highly prone to flood hazards in the Rawa Pening Sub-Watershed. Nine parameters, including elevation, slope, curvature, precipitation, land use, soil type, distance to the river, Normalized Difference Vegetation Index, and Topographic Wetness Index, were analyzed based on their respective roles. The Analytical Hierarchy Process (AHP) and Ordered Weighted Averaging (OWA) techniques were employed to obtain the flood hazard map. The nine parameters were weighted according to a Forum Group Discussion. The results yielded a flood hazard map divided into five zones: very low (3451,64 Ha / 13,16%), low (5024,29 Ha / 19,16%), moderate (6049,35 Ha / 23,07%), high (7949,67 Ha / 30,31%), and very high (3750,93 Ha / 14,30%).