An appraisal of cross section geometry resolution on predicted flood level using SFlood Model / Nor Ashidah Ishak

This report describes a study that conducted to determine the suitable cross section resolution for flood level prediction using SFlood Model (modified version of HEC-6 model). The flood risk model was test using the hydraulic and hydrological data from a study reach approximately 3km long at Pari River catchment area. Various cross section geometry resolutions such as 5m, 10m, 20m, 40m, 60m, 80m, and 100m intervals are derive by using interpolation and extrapolation techniques. Flood levels were predicted using the SFlood Model with different cross section resolutions as stated above. The predicted water levels then compared with 1997 Flood observed water level. It is evident that, the usage of high-resolution cross section geometry data yields water levels greater than the observed values. Water levels predicted with cross section geometry configuration with 20m to 60m intervals relatively agree to observe water levels. Beside that, there are fluctuations in water levels when SFlood Model is simulate as loose boundary and rigid boundary where the former always yields higher values in water levels. Design floods with ARI 50 and ARI 100 with rainfall duration 120 minutes also simulated to yield flood conditions for future land use conditions. The predicted results transformed into a flood risk map by using GIS to demonstrate the differences in flood extend when various geometry resolutions are applied.