MANAJEMEN RUNOFF KOTA SENGKANG DENGAN PENERAPAN DRAINASE VERTIKAL DAN HORIZONTAL = Sengkang City Runoff Management with Vertical and Horizontal Drainage Applied

Flood events with a height of 0.5 to 1 m are a problem for Sengkang City, which is the business centre of Wajo City. This study aims to analyze the characteristics of flood the causes of existing inundation and how to counter measure. Taking topography data, channel dimension, channel elevation, rainfall data and land use as input data in SWMM simulation. The simulation runs on rainfall intensities in 5 and 10 years return periods. Vertical and horizontal drainage techniques are used as a counter measure plan. The results showed that the lack of capacity of the existing channel led to a flood volume of 131.209 m3 (45 inundation points) 5 years return periods (R5) and a flood volume of 204.586 m3 (58 inundation points) 10 years return periods (R10). The first phaseof mitigation planning is improved channel dimensions and adding new channels can reduce the flood volume of R5 amount 56.853 m3 (32 inundation points) with an effectiveness of 43,33% and R10 amount 83.547 m3 (35 inundation points) with an effectiveness of 40,84%. In the second phase, the infiltration wells can reduce the flood volume of R5 by 5.823 m3 (1 inundation point) with an effectiveness of 4,44% and R10 amount 9.027 m3 (0 inundation point) with an effectiveness of 4,41%. In the third phase, the addition of amount 10.000 m3 retention pond in primary channel A, and amount 10.000 m3 retention pond in primary channel B, amount 3.700 m3 detention pond downstream of channel C and amount 6.400 m3 detention pond downstream of channel A, can reduce the flood volume of R5 amount 68.533 m3 (12 inundation points) with an effectiveness of 52,23%, and R10 amount 112.012 m3 (23 inundation points) with an effectiveness of 54,75%.

Keywords : Sengkang City, runoff management