Eco-Hydraulic Cross-Section Engineering for Flood Management of Kinunang River in Likupang Priority Tourism Area, Indonesia

Introduction This study aimed to apply flood management at Kinunang River, focusing on evaluating and designing the most suitable river channel geometry that will effectively mitigate destruction due to moderate to extreme flood events. Kinunang is a river located within the Likupang Special Economic Zone for ecotourism. Consequently, the river area’s precondition is flood-free, and any developments herein should adhere to eco-friendly and aesthetic principles. Methods Hydrological analysis of local rainfall data was carried out using HEC-HMS to predict the amount of flood discharge. Hydraulic analysis using HEC-RAS was applied to predict channel storage capacity, to simulate flow profile, and to assess the flow speed with the intention of minimizing scouring. Eco-hydraulic property of the designed channel cross-section was examined by simulating the effect of placing 3 different plants along the channel. Results Re-dimensioning of the river cross-section resulted in a multi-stage trapezoid channel with an upper width (La), lower width (Lb), and depth (h) of 2 m, respectively. The use of vetiver grass was able to reduce the flow velocity by 29%. Discussion The multi-stage trapezoidal cross-section was selected because it can drain the design flood discharge and facilitate the use of plants to meet the eco-hydraulic property. Vetiver grass was chosen due to its maximum amount of velocity reduction. Conclusion The Kinunang River does indeed require channel re-dimensioning. A multi-stage trapezoid channel and the planting of vetiver grass will diminish the impact of the design flood, prevent river bank erosion, and display an attractive green river bank.