Comparison of two flood risk assessment methods in the case of the Turiec river, Slovakia

Abstract

Floods are the most common natural process causing damage to property and loss of life in our geographical area. Efforts to reduce the risk of flooding require methods for assessing the flood risk. Application and comparison of these methods in the same area allows us to describe the differences which could not be discovered only by studying the procedure of these methods. Two methods of flood risk assessment and their outputs were compared in one part of the Turiec River in Slovakia. Results of these methods are different flood risk maps while the key difference is the definition of risk. Risk is defined on the entire surface of the modelled scenarios in the case of the risk map based on Method I. In Method II, flood risk represents an area with unacceptable risk which means the risk where the threshold value has been exceeded. The two methods obtained similar results regarding areas subject to the greatest risk of flood damage. However, Method II appears to be more effective. It uses flood depth and flood velocity information and includes creation of a Flood danger map – a suitable tool for urban planning. The method focuses only on the localities where it is urgent to reduce the flood risk.

Keywords

• flood risk assessment
• flood hazard map
• flood risk map
• HEC-RAS
• Turiec