The Application of retention pond system to control flooding in Southern Pontianak City

Abstract

Southern Pontianak is generally situated on lowland area with elevation varies between –0,224 m and +1,959 m. Due to its low elevation, this area is strongly affected by tidal flow. Compared to the highest tide elevation observed by PT. Barunadri Engineering Consultant at +0,213 m, it is obvious that the area is also vulnerable to inundation. Worse situation occurs as there are two channel, Sungai Jawi channel and Sungai Raya Dalam channel, which are frequently flooded during high rainfall intensity. An integrated and sustainable water management is therefore required to mitigate the flooding. Started by identifying the channel capacity to deliver flood flow, the analysis is extended to estimation of series of retention pond to control the flood. The 1-D Duflow model is employed here to simulate the water surface profile along the channels reach and estimate the capacity of ponds. Based on the simulation results, the dimension of two retention ponds required at Sungai Jawi Channel and Sungai Raya Dalam Channel are 700x 700 x 4 m3 and 350 x 350 x 4 m3 respectively. These two retention ponds are designed to control 5 years flood with maximum amount of 1,750,650 m3 and 454,740 m3 under maximum tidal condition.