Structural flood control model based on Eco-hydraulic in small watersheds (Case study of the Akelaka-Halmahera river)

Abstract

Various factors, such as the physical condition of the area, nature, and humans, influence the phenomenon of flooding. Thus, the flood control application model will differ in each region. The application of flood control structurally lowers the flood water level significantly, but it changes the ecosystem around the river. The eco-hydraulic concept is a new paradigm in watershed management to reduce the impact of floods while still paying attention to river ecosystems. This study aims to integrate structural methods with eco-hydraulic concepts in flood control in small-scale watersheds. The locus is the Akelaka watershed on Halmahera Island. Watershed morphometric analysis using the ArcGIS application, hydrological analysis for five and 25-year return floods, and hydraulics testing using the HecRAS application are used. The application of this concept uses vegetation on river slopes after normalization. The results showed that flood control which combined normalization, eco-hydraulic and structural ideas in Akelaka village, showed excellent results. The potential for inundation is reduced by up to 93% for a five-year return period flood discharge and 89% for a 25-year return period flood discharge.