Determination of forest water yield in Malaysian tropical watershed using calibrated satellite-based rainfall data

This study investigates the potential of the calibrated satellite-based rainfall estimates data product from Tropical Rainfall Measuring Mission (TRMM) satellites, known as TRMM 3B43 Version 6 or TRMM Multi-Satellites Precipitation Analysis (TMPA) water run-off modeling at tropical forested watershed scale in Peninsular Malaysia. The calibrated satellite-based rainfall is used as the main input in the Thornthwaite water balance equation to estimate the water run-off (yield) at monthly basis from 1998 to 2007. Four forested watershed which located in each main region in the Peninsular Malaysia are used as sample to evaluate the model performance. Preliminary assessment of the calibrated satellite-based rainfall at the selected forested watershed indicates good agreement with the ground rainfall measurement with average bias of ±43.35mm per month. The monthly estimated water run-off for all forested watershed in all region also shows good agreement and comparable with the simulated run-off using the rain gauged data. The average bias for the satellite-based derived water run-off for all forested watershed in all Peninsular Malaysia region is 22.7mm per month except for east region where higher values are recorded which reach 55.5mm per month.