AN INTEGRATED APPROACH FOR FLOOD MANAGEMENT: A CASE STUDY ON NILWALA RIVER BASIN

摘要

Flooding has been one of the most costly disasters in terms of both property damage andhuman casualties in Sri Lanka. Being the Nilwala a major fl ooding rivers in the country ,NilwalaGanaga Flood Management Project has been initiated to protect the area from frequent fl oodevents. Although it was planned to implement in 3 stages, the project has not been continuedfor third stage. At the third stage of the project , it was planned to take fl ood mitigationmeasures for protecting Matara city. This study is done to study the validity of river trainingproposal by way of improving river water fl ow by removing the elevated river bed to a suitableprofi le for a river section of 1.5 km from sea mouth.HEC-RAS river routing software was used.The results of the analysis shows that the Matara city is under threat of fl ooding even for 10year return period fl ood. With the river bed excavation, city is well protected against the fl oodof 10-50 return periods.