Hazard maps for flash-floods in the Thriassion Plain

Περίληψη

A geohazard is defined as an environmental condition that has the possibility of growing into a critical event. Of all geohazards, flooding is the most common and costly. The Thriassion plain has been affected by several storm flood events, causing serious hazard to life and destruction of buildings and infrastructure. The purpose of this study is to develop a GIS-aided flood hazard zoning of the area of the Thriassion plain applying Multicriteria Decision Analysis (MCDA). The model incorporates four parameters: the distance to the stream channels, slope, cover type and soil type. The weight and rank values are assigned to the layers and to the classes of each layer respectively. The assignment of the weight/rank values and the analysis are realized by the application of two different decision models, namely Multi Attribute Utility Theory (MAUT) and Analytic Hierarchy Process (AHP) methods. A hazard map for each method is obtained using an algorithm that combines factors in weighted linear combinations. The flood hazard maps that prepared as outputs of these methods are found to be consistent with each other and show that the southwest part of the Thriassion plain and also the areas close to the streams have the highest flood hazard over an extended area as consequence of the conjunction of lowlands, with slopes under 2%, and the presence of stream channels. Finally a map including hazard map overlapped by the local infrastructures also was created.