Unravelling the Complexity of Flood Hazards: A Comprehensive Review of Characteristics and Risk Assessment

Understanding the characteristics of flood hazards is crucial since it is one of the basic indicators for determining the risk of loss level. The elements of a hazard are often interpreted with varying connotations, especially flood hazards. In fact, the characteristics and scales that measure a flood hazard level also vary from one study to another. Therefore, the aim of this paper is to understand the characteristics of flood hazards and their influence on the risk of loss level by reviewing previous research. Generally, the flood hazard level can be determined according to certain characteristics, such as depth, velocity, duration, amount of discharge, flood flow force, flood intensity and energy head. Based on these characteristics, the flood hazard level can be classified into three or four levels: low, medium, high; or low, medium, high and extreme. From the aspect of depth, for example, floods with a height less than 0.5 meters and more than 1.5 meters are categorised as low and high hazard levels, respectively. In terms of frequency, floods that occur less than 6 times a year are considered as low hazard level, while those that occur more than 11 times a year are classified as extremely hazardous. The higher the flood hazard level in an area, the greater the risk of loss. Therefore, understanding the characteristics of a flood hazard will aid in determining or assessing the risk of loss in any particular area.