Estimation of hydrological changes in a tropical watershed using multi-temporal land-use and dynamic modelling

The response of a watershed due to changes in its physical environment might result in floods, river erosions and siltations, subsequently affecting humans and biotas. Evaluating land-use changes is crucial for better assessment of hydrological conditions in a watershed system. The remote sensing imagery, field data collection, and land change modelling were used to produce the land-use maps of different spatiotemporal scale from 1989 to 2039. The generated maps are integrated into Hydrological Simulation Program-Fortran (HSPF) model, to evaluate the hydrological changes in Skudai River watershed in Malaysia. Total runoff is expected to account for 57% of the rainfall influx by 2039, a change of 2% from 1989 land-use, an indication of the low response of runoff to change in land-use. As built-up land increase by 3.39%, the average streamflow will increase by 0.05 m3/s. It will further reduce actual evapotranspiration (AET) by 0.39%, groundwater by 0.34% and change in storage by 0.38%. The sensitivity analysis of the hydrological elements to the land-use changes indicates that AET being the most sensitive then change in storage, and total runoff showing the lowest sensitivity. The result of the study provides information on the long-term impact of land-use on the hydrology of the tropical watershed, and it can be a useful tool in the planning and management of a watershed in a different perspective