Evaluasi Kapasitas Penampang Sungai Mencirim Kota Binjai terhadap Debit Banjir Menggunakan Metode HEC-RAS

Abstract

Flooding is a natural disaster that always comes in the rainy season. This disaster has had a huge impact on the population, especially on the river bank. One of the factors causing the flood was also triggered by the unwanted dumping of garbage. The purpose of this research is to find out the crossing capacity of the river and to find the correct flood control solution on the flow of river. In doing so, some analysis is needed, namely the analysis of maximum average rainfall, analysis of flood discharge, and a flood unit hydrograph. The analysis is done using the rainfall data of 3 rain stations and calculation analysis using the Nakayasu HSS Method. In determining the flood flow, rainfall analysis is carried out using the Thiessen Polygon Method and determines the spread of rainfalls data. Then a probability distribution test. The result of the analysis using the Nakayasu HSS method is the repeated discharge of the flood at the specified time. To determine the capacity of the river crossing using HEC-RAS 6.0. Based on the calculations with the Nakayasu HSS Method, the peak flood discharge was 8,285 m3/second with peak time at 1.62 hours. The result of the analysis of the plan's Flood Discharge with the HSS Nakayazu Method at 2 years, 5 years, 10 years, 25 years, 50 years, and 100 years in a row was 477,694 m3/s, 512,205 m3/s, 525,118 m3/s, 535,372 m3/s, 540,268 m3/s, and 543,670 m3/s. The results of the calculation of the crossing of the Mencirim River, which has a capacity of 17,023 m3/s and a flow speed of 0,806 m/sec, were obtained. Based on the analysis of the capability of the mencirim river, using HEC-RAS 6.0 with the flood discharge of the Nakayasu HSS plan on all the anniversary shows that the existing capacity is not meeting the plan