Estimation of the Potential Trend Changes on the Streamflow with Climatic Responses Consideration

Abstract

Uncontrolled rapid development will create the negative effects especially to the unstable climate variability. In Malaysia, the huge impact to this trend changes can be examined during North-East monsoon. The most of rivers in the Eastern parts of Malaysia are exposed to the drastic and unexpected water level (WL) rises. The objective of this study was to estimate the potential changes on streamflow at Sg Yap with climate change impact. Sg Yap is a part of Pahang River basin and recorded as the worst affected area of flooding in year 2017. Thus, the integration of climate model (SDSM) considered the representative concentration pathway (RCPs) and rainfall-runoff model (IHACRES) were implemented. According to the results, the selected predictors for climate simulation were successfully to have good association with the local rainfall and temperature stations. High correlation (>0.79) and least of percentage error (<21.51%) as proved the accuracy and reliability of the findings. In the long term projection, the temperature was expected to decrease in average 6%. Meanwhile the long term rainfall trend was slightly similar to the historical trend with small percentage of decrement in the annual rainfall as -8.1% (RCP2.6), -10.2% (RCP4.5), -10.8% (RCP8.5). Thus, the long term streamflow at this region is expected to decrease with 20.9%, 22.1%, and 27.9% by RCP2.6, RCP4.5 and RCP8.5, respectively. Therefore, the relationship between rainfall-runoff can be estimated in the ratio of 1:3 (RCP2.6), and 1:2 (RCP4.5 and RCP8.5).