Disentangling the effects of long-term changes in precipitation and land use on hydrological response in a monsoonal catchment

Abstract

This research aimed to quantify the effects of precipitation and land use changes on the hydrological response (peak discharge and runoff volume) in the River Kelantan catchment, Malaysia. Two periods were studied, involving the years 1988 (lower hydrological response) and 2004 (greater hydrological response). Rainfall and land use observed for the year 1988 was used in the calibrated and validated model for 1988, but also used in the calibrated 2004 runoff model to simulate the impact of changes in these two factors on runoff generation. For the upstream gauge, differences in peak discharge and runoff volume were affected more by land use change compared to climate-related changes (i.e. precipitation). However, changes in hydrologic response in the downstream catchment were much more associated with precipitation changes. From these findings, we suggest that both land use and climate changes (i.e. precipitation) contributed to changes in hydrologic response in the Kelantan monsoonal catchment, but that for the downstream catchment, which is more prone to flooding, with associated potential socio-economic impacts, precipitation change is the major driver. The results have clear implications for planning and management decision-making.