Dynamic flood inundation model - a case study at Damansara catchment / Awang Nasrizal Awang Ali

Damansara Catchment is flood prone and major problem for the dense populated region is the damages received during flood. High intensity rainfall of 104 mm/day on 26th February 2006 had affected several areas to be heavily inundated with losses up to RM 45 millions. Thus, there is a need to conduct a study. This project presents a 3D (three-dimensional) hydrodynamic flood simulation that utilizes GIS (Geographic Information Systems). A DEM (Digital Elevation Model) for Damansara Catchment was developed and integrated into InfoWorks River Simulation (IWRS) program. The model was calibrated and validated using the 26th February 2006, 21st March 2007 and 15th October 2008 flood event. The parameters involved in calibration are the CN (Curve Number), Manning's Roughness Coefficient («) and River Profiles Extension. In model reliability analysis, the ratio of Linear Regression, R2 was found to be hard to be calibrated, probably due to changes in river profiles. MWLA (Maximum Water Level Analysis) and RMSE (Root Mean Square Error) both show error less than 9.09% and 0.90% respectively, and in Chi-Square Test, p>0.90, thus indicating that the difference between actual and simulated water level is not significant and that the model is satisfactory. Inundated areas such as TTDI Jaya are able to be identified from inundation map. An alternative natural retention pond, RPOOl is proposed at the upper catchment of Kampung Melayu Subang through the utilization of existing terrain 'bowl'. With improvement on the catchments' soil cover, RPOOl pond was simulated to be able to reduce both flood level and volume up to 2.90% and 4.10% respectively.