Effects of Nipa-Nipa Regulation Pond on Flood Control of Tallo River

Abstract

The Nipa-Nipa Regulation Ponds are a flood control building for Makassar City and its surroundings due to the overflow of Tallo River downstream with an operating system to accommodate air. Regulation pond is only able to accommodate part of the peak flood discharge which caused Tallo River to overflow. For this reason, an analysis is carried out on how the influence of the Nipa – Nipa Regulation Pond on flood control of the downstream Tallo River is carried out. The analytical method used is a hydraulic analysis with the help of the HEC-RAS application. Based on the results of the 2D HEC – RAS numerical simulation mapped for the downstream area of Nipa - Nipa Regulation Pond, it is obtained that regulation can reduce surface runoff due to the overflow of the Lower Tallo River for Q2 by 183.97 Ha (35.59 %), Q5 271 .85 Ha (37.19 %), Q10 was 249.35 Ha (28.50 %), Q20 was 291.63 Ha (28.18 %), and Q25 was 300.67 Ha (28.08%). From these results, it can also be seen that the current condition of the Nipa – Nipa Regulation Pond is the most effective way to deal with flooding downstream of Tallo River at the five-year return period (Q5).