Study of inundation control on Kelayan Regional Inundation Handling Unit in Banjarmasin, South Borneo

Inundation occurred in high density urban areas is a major issue especially in low land because it potentially damage the affected infrastructure. In this research, a case was taken in Kelayan Regional Inundation Handling Unit in Banjarmasin City, South Borneo. The purpose of this study is to determine cause of the inundation and provide recommendation for reduced it. The hydrological analysis was calculated by using the rational method, using data from Sungai Tabuk Rain Station that 24 years long. From the discharge obtained, then the required channel dimensions could be calculated and compared with the existing channel dimensions. The hydraulic analysis was performed by HEC-RAS model with the discharge as boundary condition, and topographic data to determine channel elevation. As the results, the existing drainage channels can only cover 39.85 of the entire area, and almost all of these existing channels cannot drain the discharge that occurs, therefore it becomes an inundation. For example, channel number 4.C.14c the existing channel has 0.5m width and 0.7m depth, it caused inundation as high as 39cm upstream. After normalized the channel by increasing the dimensions to 2.1m width and 1.3m depth, the discharge does not overflow so there is no inundation.