ANALISIS DEBIT BANJIR RENCANA PADA SUB DAS DELI MEDAN

Abstract

ABSTRACT

The Deli River Basin (DAS) is located in North Sumatra Province, specifically in the city of Medan. Flooding poses a significant risk to this area. This risk is caused by several factors, including the conversion of land around the watershed from a water catchment area to residential, commercial, and service areas. This land use change has drastically reduced the water-holding capacity of the Deli River Basin. Furthermore, the extreme climate that occurs in most parts of Indonesia and errors in the implementation of Medan's spatial planning have exacerbated this situation. Therefore, an in-depth analysis is needed to determine the potential flood discharge in the Deli Sub-watershed area. The analysis was conducted using rainfall data from 2013 to 2022. The method used was the Nakayasu Synthetic Unit Hydrograph (HSS), and simulations were conducted using HEC-HMS software. The results of the analysis of the planned flood discharge in the Deli Sub-watershed using the Nakayasu HSS method for return periods of 2, 5, 10, 25, 50, and 100 years are, respectively, 163.65 m³/second, 180.20 m³/second, 188.67 m³/second, 197.51 m³/second, 203.10 m³/second, and 208.00 m³/second. Meanwhile, the results of the analysis using the HEC-HMS simulation method for the same return period obtained the following results:306.9 m³/second, 344.6 m³/second, 361.0 m³/second, 378.0 m³/second, 388.8 m³/second, and 398.3 m³/second. The calculation results show a significant difference between the Nakayasu HSS method and the HEC-HMS simulation, illustrating the importance of selecting the appropriate method in flood control planning in the Deli Sub-watershed.