Abstract
A hydraulic characteristic analysis was conducted to support the plan to construct the
Cisangkuy River Weir in the Cikalong Hydroelectric Power Plant area, aiming to improve the
fulfilment of raw water needs entering the inlet system of the South Bandung Regional Water
Company. The main problem faced is the seasonal discharge fluctuations and watershed
degradation, which cause the intake discharge during the dry season to only reach 0.09 m3/s,
far below the minimum requirement of 0.7 m3/s. This study uses a research methodology
that includes hydrological data collection, river cross-section surveys, and hydraulic
modeling using HEC HMS and HEC-RAS 1D version 6.3.1 software. The simulation results
show that the construction of a weir height of 1 m and a width of 1.5 m with a sluice gate
system can significantly increase the intake flow rate. In dry conditions, the optimal flow rate
reaches 0.62 m3/s without downstream flow, if the hydroelectric power plant operates and
the gate is opened 0.1 m, the flow inlet conditions will be 0.55 m3/s with a downstream
inflow of 4.69 m3/s. In the rainy season, optimal conditions are achieved at a return period
of 2-5 years by fully opening the two weir gates so that the water surface elevation does not
exceed the peak of the hydroelectric power plant (+885.5 m) with an inflow discharge
between 0.51 and 1.20 m3/s. The integration of the weir with adaptive sluice gates has
proven effective in ensuring the sustainability of raw water supply while mitigating flood
risks.
Cisangkuy River Weir in the Cikalong Hydroelectric Power Plant area, aiming to improve the
fulfilment of raw water needs entering the inlet system of the South Bandung Regional Water
Company. The main problem faced is the seasonal discharge fluctuations and watershed
degradation, which cause the intake discharge during the dry season to only reach 0.09 m3/s,
far below the minimum requirement of 0.7 m3/s. This study uses a research methodology
that includes hydrological data collection, river cross-section surveys, and hydraulic
modeling using HEC HMS and HEC-RAS 1D version 6.3.1 software. The simulation results
show that the construction of a weir height of 1 m and a width of 1.5 m with a sluice gate
system can significantly increase the intake flow rate. In dry conditions, the optimal flow rate
reaches 0.62 m3/s without downstream flow, if the hydroelectric power plant operates and
the gate is opened 0.1 m, the flow inlet conditions will be 0.55 m3/s with a downstream
inflow of 4.69 m3/s. In the rainy season, optimal conditions are achieved at a return period
of 2-5 years by fully opening the two weir gates so that the water surface elevation does not
exceed the peak of the hydroelectric power plant (+885.5 m) with an inflow discharge
between 0.51 and 1.20 m3/s. The integration of the weir with adaptive sluice gates has
proven effective in ensuring the sustainability of raw water supply while mitigating flood
risks.
Keywords
Cisangkuy river
HEC-RAS 1D
Hydraulics
Water supply discharge
Weir.