RELATING CLIMATE VARIABILITIES ON BASEFLOW INDEX IN WAY SEKAMPUNG RIVER AT KUNYIR STATION

Baseflow is very important for water resource management such as irrigation, hydropower generation as well as low-flow forecasting. Baseflow conditions and streamflow volume can be expressed in variability of Baseflow Index. Climate variability, i.e. seasonality and climate change such as El Nino may influence streamflow processes as well as baseflow. Therefore it is important to examine the effect of seasonality and El Nino on baseflow index. This study purposes to investigate the effect of seasonality, i.e. wet and dry seasons, and the effect of El Nino on baseflow index in Way Sekampung River at Kunyir Station. Observed discharge data recorded from the hydrometry station Kunyir is analysed using Recursive Digital Filter (RDF). The result shows that BFI during dry season is higher than that during wet season and BFI in dry seasons during El Nino years are higher than those during normal years. Thus the effect of climate variabilities such as seasonality and El Nino on baseflow index has proven in this study. However, the operation of Batutegi Dam located upstream of Kunyir Station since 2003 has alters baseflow index pattern which does not show the effect of El Nino on baseflow index during El Nino years