Two-Dimensional Modelling for Dam Break Analysis and Flood Hazard Mapping: A Case Study of Papadia Dam, Northern Greece

Abstract

Dams are expensive technical constructions that ensure food production, sustain farmers’ income, and cover a large percentage of urban water supply demands. However, the threat of a dam break flood, which can be extremely dangerous for the local society, should be taken into account, and proactive mitigation measures should be planned. Towards this direction, dam break modelling and flood hazard assessment are essential for developing flood crisis management and evacuation plans. In this study, a hypothetical case of failure of the Papadia dam in the Florina Regional Unit in northern Greece is examined. Two scenarios of failure were considered: overtopping and piping. A two-dimensional numerical model for the two failure scenarios was used to simulate the dam break process and flood wave routing using HEC-RAS software. A sensitivity analysis of the mesh size and breach parameters was performed to better understand their impact on the critical outputs of the simulation model. Flood hazard maps were produced in GIS environment based on water depth and velocity criteria. Furthermore, two classification approaches were adopted to assess the flood hazard using the product of water depth and velocity. The results showed that the extent of the inundated area could affect most of the study area and could cause severe damage to agricultural activities.

Keywords

• dam break
• 2D HEC-RAS model
• overtopping
• piping
• flood hazard mapping
• sensitivity analysis