Flood risk assessment of river “Kelani Ganga” exceeding its threshold water level

Charith Dushyantha,Irina Ptuhina,S Kudriavtcev,V Murgul

doi:10.1051/e3sconf/202015702006

Charith Dushyantha, Irina Ptuhina + Show 2 more

Open Access

https://doi.org/10.1051/e3sconf/202015702006

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Abstract

Flood risk assessment curves were developed for a flood risk assessment carried out in Colombo, Sri Lanka. Annual maximum water levels at three gauging stations in Kelani Ganga were used as data to prepare the flood risk assessment. Information sources include the Ministry of Disaster Management, Irrigation department and Department of Metrology. Current approaches to risk assessment function development were improved by using the extreme value theory. The most suitable model from the extreme value theory was defined by the behaviour of the probabilistic density function. The probability of a threshold water level exceeding in a given year can be predicted by using the developed model. According to the results of the flood risk assessment at the three gauging stations along river Kelani Ganga, the Hanwella station is at an 89.3% high risk of inundating the area with the water level reaching up to 9.6m in 10 years of time. These results can be used to develop hazard maps for these areas as one of the criteria that must be taken into consideration when choosing the optimal site for construction.

Highlights

Floods are the most destructive form of natural hazards in both local and global contexts
Models for risk assessment of water level of river Kelani Ganga exceeding the threshold level were developed by using data about the annual water level at the three gauging stations Nagalagam, Hanwella and Glencourse
It is evident that risk assessments of the water level exceeding the threshold level in the shorter periods of time of five and ten years are most crucial for the responsible authorities to take necessary measures in order to minimize flood vulnerability in the relevant areas

Summary

Introduction

Floods are the most destructive form of natural hazards in both local and global contexts. This is true in terms of both loss of life and property damage. It is the most prevalent form of natural hazard. No country in the world, except the most arid, can be thought as entirely free from flooding. In certain regions flooding is more prevalent than others. Asian continent is found to be one of the most flood affected regions in the world. Having floods is more common than any natural hazard in Sri Lanka. People have taken some actions and have been prepared to minimize the flood risk in urban areas, the risk of the area being inundated is still there due to heavy rains of monsoons

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