| Abstrak/Abstract |
This research was conducted in the Seropan underground river located in the Gunung Sewu karst area, Gunung Kidul Regency. The purpose of this study was to identify some of the flood hydrograph properties of the Seropan underground river to characterize the karst aquifer. A water level data logger is installed to detect underground river water level fluctuations during the recording period. In addition, time series discharge measurements at minimum, average and maximum flow are carried out to formulate a stage-discharge rating curve. Thus, the hydrograph of the underground river during the measurement period can be determined. After that, several flood hydrographs were selected to calculate the diffuse flow recession (Kb), fissure flow (Ki), conduit flow (Kc), time to peak (Tp) and time to base flow. The results of the analysis show that the Seropan underground river has a fairly fast response to rain events (Tp = 3.5 hours). Then, the calculation results show the value of the recession constant (Kb = 0.995; Ki = 0.863; Kc = 0.666) which means that the Seropan Cave underground river still has a large enough base flow deposit with a fairly slow release (Tb = 45.3 hours). This base flow deposit is reflected in the minimum discharge during the dry season above 300 ltr/second. |
