Flood forecasting model for Kelantan river basin, Malaysia using ifas and getflows

Abstract

The effectiveness of real time flood forecasting systems in reducing flood damage would depend upon how accurately the estimation of future stages or flow of incoming flood and its time sequence at selected points along the river could be predicted. Warning of the approaching floods provides sufficient time for authorities to evacuate the affected people to a safer place and to make intense patrolling of flood protection works such as embankments. The Kelantan river basin, located in the north east of Peninsular Malaysia is one of the biggest watersheds in Malaysia spreading over 12,000 km2, and has been damaged seriously by monsoon floods/inundations in many places along the river and its tributaries in midstream to downstream areas. Thus constructing a reliable system for early warning and evacuation, as well as making countermeasures for reducing the magnitude of damages, is crucial requirement here. Basically there are two types of flood modelling developed in this study; inundation modelling and whole watershed modelling. In inundation modelling, flow of runoff prediction using Integrated Flood Analysis System (IFAS) starting with the observed rainfall and discharge and setting and tuning of PWRI distributed parameter for rainfall-runoff model. IFAS then will simulate the rainfall-runoff simulation using projected precipitation. IFAS will execute on the hydrological part and river analysis from the data feed from INFOBANJIR to convert the rainfall into runoff. The IFAS runoff output will be the input into General-Purpose Terrestrial Fluid Flow Simulator (GETFLOWS) model for the inundation analysis. The time for calculation is up to 6 hours ahead by GETFLOWS is within 10 min/site. Including graphic processing, the results will become available within around 15 min. Where as in whole watershed modelling, GETFLOWS is used to generate runoff output (longer calculation time compared to IFAS). The time calculation is up to 6 hours. Including graphic processing, the results will be available within around 25 minutes.