IMPACT OF CHANGES IN CLIMATE AND LAND USE ON THE FUTURE STREAMFLOW FLUCTUATION: CASE STUDY MERANGIN TEMBESI WATERSHED, JAMBI PROVINCE, INDONESIA

Abstract

Beside land use change, future climate change potentially alters streamflow fluctuation of a river basin in Indonesia. We investigated relative impact of changes in climate and land use on the streamflow fluctuation of a watershed in Jambi Province, Indonesia for future condition (2025). To account for the climate change, we simulated future rainfall and temperature scenarios using the downscaled rainfall and mean surface temperature of 24 CMIP5 GCM outputs with moderate scenario of RCP4.5. We used distributed hydrologic model (SWAT) to simulate relative impact of changes in climate and land use on the future streamflow fluctuation. The SWAT model performed well with the Nash-Sutcliff efficiency values of 0.80-0.85 (calibration) and 0.84-0.86 (validation). The results indicated that the climate change caused 32% decrease of the minimum discharge during dry season and 96% increase of the maximum peak discharge during rainy season. Meanwhile, the land use change led to 40% decrease of the minimum discharge in the dry season and 65% increase of the maximum peak discharge in wet season. Both changes indicated significant impact on the extreme events such as discharge and minimum discharge. The impact of the climate change on the increased peak discharge is more significant compared to that of the land use change. Meanwhile, the impact of the land use change on the minimum discharge is more significant compared to that of the climate change. The results of this study pointed out that both climate and land use changes potentially become crucial factors for the future discharge fluctuation in Indonesia.