Predicting Flood Hazard Indices in Torrential or Flashy River Basins and Catchments

Davor Kvočka,Roger A Falconer,Reza Ahmadian

doi:10.1007/s11269-018-1932-6

Abstract

Flood hazard maps are one of the main components of any flood risk management strategy. It is predicted that the degree of flood risk is going to significantly increase in the future due to climatic and environmental changes, and hence it is increasingly important that state-of-the-art methods are implemented for assessing human stability in floodwaters. Therefore, this paper focuses on proposing more accurate and detailed guidelines for predicting flood hazard indices in small and steep river basins or catchments, prone to the occurrence of flash flooding. The results obtained in this study indicate that for river basins with an average bed gradient greater than 1% (i.e. torrential or flashy river basins or catchments), then the flood hazard indices should be predicted using criteria which are based on the physical interpretation of the processes that affect the human stability in floodwaters, i.e. mechanics based and experimentally calibrated flood hazard assessment methods.

Highlights

Flooding is the most commonly occurring natural disaster, which affects the largest number of people worldwide, and can lead to thousands of fatalities and enormous economic damage
This was as expected, since the formulae based on empirical or quasi-theoretical studies are as accurate as mechanics based criteria for flood events that are characterised with generally low velocities and a low Froude number (Kvočka et al 2016)
This confirms that the mechanics based approach can better adapt to higher or rapidly changing velocities, and can more realistically predict the flood hazard risk indices for flood events characterised by high-velocity and high-Froude number flows, such as flash floods

Summary

Introduction

Flooding is the most commonly occurring natural disaster, which affects the largest number of people worldwide, and can lead to thousands of fatalities and enormous economic damage. Most of the criteria used to assess the stability of people in floodwaters is derived from a mechanics based analysis linked with experiments (Abt et al 1989; Karvonen et al 2000; Jonkman and Penning-Rowsell 2008), or based on a simple empirical analysis of experimental data only (Keller and Mitsch 1993; Lind et al 2004; Ramsbottom et al 2006) These criteria are often based on excessive simplifications of the anatomical characteristics of a human body and the hydraulic characteristics of the flow, and are usually too dependent on the physical and psychological characteristics of the tested subjects (Xia et al 2014). This enables more accurate predictions to be made of the flood hazard indices, which is relevant for flood hazard assessment in areas prone to the occurrence of extreme flood events (Kvočka et al 2016)

Objectives

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Results

Conclusion