CAPACITY ANALYSIS CILIWUNG RIVER CROSS-SECTION OF THE BRIGDE KALIBATA UNTIL MANGGARAI WATER GATE AND DOOR OPENINGS TO DRAIN THE FLOOD DISCHARGE

Abstract

In 1900, the Ciliwung river is still in a comfortable condition, in 2007 and 2014, the Ciliwung river conditions are getting worse, it is because a river filled with a lot of hard inorganic waste is described and conversion are not running not walk. Sta 0+100 to with Sta.3+800 is thelocation Manggarai up to Kampung Melayu width of the river in this segment an average of approximately 15 meters, the depth of the groove main river this segmen is relatively shallow because the capasities of the groove that is lower than the discharge annual floods of the past sothat each year land and settlements along the roads were flooded when the season rain. Is this segment to anticipate the outburst flood, improving the capacity (to deepen and widen the groove then by retrofitting a cliff). Purpose of the study wanted to know how much of the cross section of the river on the existing condition of the bridge Kalibata up to Manggarai and to know the door openings to drain water discharge at a specific return period.

Stage calculation on hydrological analysis that begins with the collection of rainfall data were selected from these data, the calculation method thiesen, distributions received is along Pearson III and distribution Gumbel, then from the analysis of flood design in get debit return period of 50 yearsfor 366.94 m³/s using Nakayasu HSS. With 4.1 HECRAS program plan flood debit result in complications with the data cross –section of the river, the river cuts lengthwise (long section),and a map of the location of the long cross sectional shape and condition of Ciliwung river after an increase in Capacity.The results of simulation modeling in flood water level can comparison, followed by analyzing opening the floodgates with a program HECRAS 4.1 with few alternative door openings in the flood discharge drain.

Hydraulics analysis shows that the existing condition of the river is no longer able to accommodate the flood discharge. Of the analysis concluded that the increase in capacity it produces a decrease in the water level at 6,49 m, on the location Kalibata namely in Sta. 8+700 a decrease in speed of 3,8 m/s at Kalibata brigde location in Sta. 9+000, the average reduction in speed is 0,58 m/det. Q2th,Q5th,opened in openings Q10,Q20,Q25 years opened the door opening 6 meter.Because at these alternatives floodgates able to drain flood discharge design.For openings in the year theyoccur Q50 overflow level rise 6%, so the Q50 years in fully opened state of the door opening