Flood Risk Assessment in Post Antiao River Control Project in Catbalogan City, Philippines
Flooding in cities of developing countries is common, primarily due to poor planning and project designing and execution. Factors causing floods are due to increase population, outdated and non-functional drainage system, heavily silted and reduced river size, poor waste management, no erosion control measures, reduced vegetative cover and the unusually heavier precipitation. In response to this flood problem, the local government asked help from the Department of Public Works and Highways which in turn developed a Flood Management and Drainage System Master Plan wherein a River Control Project which includes desilting of an almost 2km stretch of the river, and the construction of river walls. Using a hydrologic modeling system (HEC-HMS) version 4, river discharge was calculated for at least four extreme events. Results have shown that the project will not solve the flooding problem due to extreme precipitation. The river walls are more needed upstream than the downstream portion of the river while the disiltation of the river is not enough to carry storm water. There is, therefore, an urgent need to construct river walls in the upstream as well as other interventions specified in the master plan to manage the flooding problems in Catbalogan.