| Abstrak/Abstract |
Diffuse flow or baseflow of karst underground river is a dependable flow to recharge the
underground flow within dry season. This research is conducted in Gilap Cave, which is
located in the upper part of Bribin River. This location has a premeditated point for sustainable karst water along Bribin River. The main objective of this study is to separate the components
of Gilap underground river flow, with the intention of defining the proportion of baseflow
component during the period of measurement. A water level data logger is installed during the
period of one year to determine the variation of water level during dry season, rainy season and
when the prevalence of flood events. Subsequently, several times of discharge measurement at
the time of high, medium and low water level is carried out to define stage-discharge rating
curve. Then, baseflow separation is conducted using automated baseflow separation by digital
filtering method. Digital filter value is obtained from constant recession analysis of flood
events all over the year, which is correlated with Baseflow Value Maximum Indices (BFImax)
within karst aquifer. The result shows that during one year, 41 flood events occur in Gilap
Cave with digital filtering value of 0.996. In addition, the calculation of diffuse flow
percentage performs that the overall value of the ratio is close to a number of around 80%.
Meanwhile, the percentages within flood events vary with the range between 45-75%. From
these figures, it generally confirms that diffuse flow is still dominant to recharge dependable
flow within upper stream of Bribin River, especially in the dry season. |
