SPATIAL MODELLING OF LOCAL FLOODING FOR HAZARD MITIGATION IN SURAKARTA, INDONESIA

Floods are one of hazards that periodically occur in Surakarta, Indonesia. This flooding has caused damage to road infrastructure, disrupted socioeconomic activities of the community, and disturbed road traffic. However, there is no ongoing disaster management to minimize the risk. Mitigation activity is an important component in the disaster management that is needed to minimize the impact of flooding. Spatial analysis and modelling is part of disaster mitigation as it can be used to predict the spatial extent of floods. The purpose of this study is to develop a spatial model of flooding using the rational modification method. The stages in this research include creating flood evaluation model, model validation, and model visualization. This study used secondary data accompanied by field observations. The datasets consist of rainfall data, slope, vegetation cover, soil type, area, surface storage, water infiltration volume, and drainage capacity. All data was then analysed by descriptive quantitative techniques. For the flood modelling, Geographic Information System (GIS) technology was used with two scenarios namely A and B. Based on the results of scenario A with a rainfall intensity of 93.2 mm/hour, and scenario B with a rainfall intensity of 136.6 mm/hour, the flooding occurred throughout Surakarta. In addition, the results of the Focus Group Discussion with the Public Works and Spatial Planning Office of Surakarta City found that hydrological data modelling had not been utilized in making drainage channels for flood prevention, which eventually resulted in floods still occurring during the rainy season.