Prediksi Debit Aliran Masuk Ke Telaga Menjer Menggunakan Persamaan Neraca Air Dan Pemodelan Hec-HMS

Abstract

The Menjer lake is the main source for Hydroelectric Power Plant of the PLTA Garung. Information about the water balance and the potential of existing water resources in the Menjer Catchment Area (DTA) is needed to obtain an efficient operating pattern, the sustainability of the Garung hydropower plant, and good management of the Menjer Lake. The purpose of this study was to estimate the inflow of three main rivers in the Menjer catchment area using HEC-HMS hydrological and water balance approach. Simulated results of the HEC-HMS model shows that the average of total the inflows of three main rivers to the Menjer lake in 2017, 2018 and 2019 during rainy season are 0.954 m3/s, 0.944 m3/s, and 1.017 m3/s, and during dry season are 0.820 m3/s, 0.783 m3/s, and 0.80 m3/s, respectively. While the prediction results of the discharge with the equation of the water balance shows that the average of total river inflows to the Menjer lake during rainy season is 2017 is 1.628 m3/s, in 2018 it is 1.579 m3/s, and in 2019 it is 3.296 m3/s and during dry season is 1.893 m3/s in 2017, 1.176 m3/s tahun 2018, and 1.893 m3/s in 2019. These results indicate that the results of discharge modeling with HEC-HMS are smaller than those predicted by the water balance equation. The study concluded that HEC-HMS could be used to predict daily inflows. However, further calibration and validation need to be carried out by recommending installing a river flow monitoring station at each river outlet.Keywords: water balance HEC-HMS, inflow prediction

Calibration and Validation of CN Values for Watershed Hydrological Response

“…The small values of R 2 and NSE indicate that in the future it will be necessary to identify in more detail the parameters that influence watershed modeling in Indonesia, for example, the results of modeling and analysis of discharge generation with HMS-HEC in Menjer Lake, including the results of spatial analysis in ArcGIS the results are quite good because more detailed identification has been carried out, including more rational values for the physical characteristics of the sub-watershed such as the slope factor, CN value, and percentage of water tightness. In addition to a more detailed identification of the parameters, it is also necessary to note that there may be other parameters that affect the balance, such as lake outflow and groundwater flow [16]. In the future, it is necessary to identify more thoroughly the HEC-HMS parameter, then determine which will most affect the conversion of rain data into a runoff.…”