GIS-Based Multi-criteria Approach Towards Sustainability of Flood-Susceptible Areas in Giofiros River Basin, Greece

Abstract

This paper describes an approach for the identification of flood-susceptible areas contributing to the sustainability of these in the Giofiros river basin covering an area of 184 km2, located in Southern Greece. This basin is prone to flooding with devastating consequences on people, environment, and the economy. In this context, a geographic information system (GIS)–based multi-criteria decision analysis (MCDA) method for the identification of potential flood-prone areas at basin scale is initially presented. Upstream of the very high flood–susceptible areas of a simulated point is selected, which is the outlet of the created subbasin (169 km2). In this area, a hydrological analysis is conducted based on the unit hydrograph (UH) theory simulating the rainfall-runoff process. The UH is calculated by applying three different methods: the time-area diagram method into the GIS environment, the Soil Conservation Service (SCS) UH, and the Snyder synthetic UH. The results show that the two last methods underestimate the flood peak in relation to the results of the time-area diagram method. The hydrological analysis is completed through Hydrologic Modeling System (HEC-HMS) software from which three flood hydrographs are produced. The flood hydrograph calculated using the time-area diagram method is imported into the River Analysis System (HEC-RAS) software in order for a hydraulic simulation to be performed. The simulation output resulted in flood hazard mapping with the maximum depth and maximum velocity along the simulated section of the mainstream downstream of the simulated point. The results of this approach appear to be extremely useful for preventing flood disaster and making disaster mitigation plans.