Page - 549 - in Book of Full Papers - Symposium Hydro Engineering

Water Level Discharge H (cm) Q (m3/s) Normal < 80 < 90 Level III 80 - 150 90 - 276 Level II 150 - 200 276 - 442 Level I > 200 > 442 Flood Alert River Flow Conditions: a. Condition 1 : For low flow with discharge is smaller than tunnel capacity, water level in the beginning of tunnel is lower than or as same as the height of tunnel. Water flows with free flow condition inside the tunnel. b. Condition 2 The flood discharge exceeds the tunnel capacity, water will flow up but the level is still lower than spillway crest elevation. Water flows through the tunnel with pressured condition. c. Condition 3 The flood discharge exceeds the tunnel capacity, water will flow up and exceeds the spillway crest elevation. Water will flow through the tunnel with pressured condition and overflow through spillway crest. Considering the need for flood reduction, the concept of control on Ciawi Dam and Sukamahi Dam is as follows: a. Changing the flow pattern of streams that under existing conditions flow through the natural river channel with the average width of the river bottom 13- 15 meters, into a controlled flow by making the dam with the flow of water through the tunnel. b. As a result of the system, the outflow capacity through the tunnel will be smaller than the natural river, so the water flowing downstream is also smaller. c. Dam function in the above conditions is to hold the elevation of the rising water surface due to outflow outflow through the tunnel is smaller than inflow discharge. d. Dam is equipped with spillway, so if the flood discharge happened big enough, the water level of the reservoir rises and the water flows through the spillway. The discharge going downstream of the dam is the total discharge that flows through the tunnel and through the spillway. 2. EXISTING CONDITION OF CILIWUNG RIVER Water level on Katulampa Weir in the up stream of Ciliwung River currently use as flood reference for the down stream. The limits which are used as the standard of flood early warning are: Table 1 Katulampa Weir as Flood Alert 549