Author(s): B. S. K. De Silva, P. S. D. Aluwihare, J. Chandimala
Linked Author(s): Shriyangi Aluwihare
Keywords: Deduru Oya, Flood model, Flood maps, GIS, Non � structural solution
Abstract: Floods have become a major hazard to lives and infrastructure in Sri Lanka, but the management techniques adopted are extremely limited. This limitation is mainly due to the lack of knowledge in identification and assessment of flood risk in respective areas. The lower Deduru Oya basin in Sri Lanka is frequently affected by floods. A major flood disaster occurred in December 2014 and the damages were catastrophic in the lower reach of the Deduru Oya basin. This study focuses on introducing a flood management system for the Panawa area in Rasnayakapura DS division, situated at the lower reach of Deduru Oya river. The objective is achieved by developing a flood model for the study area using HEC-HMS hydrological model, HEC-RAS hydraulic model and HEC-GeoRAS in ArcGIS interface. The model has been calibrated and verified using actual flood levels observed during extreme flood events in 2014 and 2015 respectively. The water levels obtained as the output data of HEC-RAS were then exported to HEC-GeoRAS in ArcGIS interface, where the results of the hydraulic modelling could be visualized in the form of flood maps. The maximum flood map was subsequently superimposed on a Google Earth map which enabled the identification of flood vulnerable zones and safe zones in the study area. A comprehensive non-structural solution including a flood forecasting method, an early warning system and evacuation procedures has been proposed as the most sustainable solution to the flood problem in the selected study area
Year: 2017