Time and Cost Efficiency of Kedunglarangan River Normalization Using Channel Design Optimization

Flood often occurs in the downstream of Kedunglarangan River as a result of river's capacity reducing. Some efforts were conducted by normalization in a form of dredging, widening, and the making of river embankments. Physical activity in the field is still running now, but in this study simulation is conducted as scientific study to get design alternative which saves more in time and cost in the implementation. Specifically, the aims of this study are 1) doing hydraulic simulation to get alternative of normalization design with 2 year return periodic plan (Q2) of flood debit to know the river's condition. 2) determining work's volume after applying the design alternative, 3) determining the comparison between cost and time of the implementation based on the volume of normalization work before and after design alternative applied. The result of analysis of the water level profile using HEC-Ras shows that: 1) Alternative design is able to flow the debit with 2 year return period, 2) work volume after normalization design alternative applied for soil excavation using Ponton Excavator at the previous design is 922.402.19 m3 , meanwhile at the alternative design gest 826.577,32 m3 , 3) the amount of time and cost comparison for the implementation of previous normalization design with cost IDR 178,717,842,203.45 can be done in 21 months as the schedule in the contract plan, while using alternative design using cost IDR 163,335,103,433.64 can be done in 19 months