Author(s): Joko Sujono, Muhammad Sulaiman, Rachmad Jayadi
Linked Author(s): Joko Sujono
Keywords: Retarding basin, retention basin, flood mitigation
Abstract: Flood events and magnitude of Belik River, which flows through Universitas Gadjah Mada (UGM) campus area, is expected to become more frequent in coming years. On December 30, 2012, there was a big flood causing a school dormitory wall at Sagan village to collapse. In 2013 alone, at least three times that flooding have occurred in the area. Floods due to overflowing Belik River inundate some villages located at downstream of the UGM area. For flood mitigation, efforts involving the managing and control of flood are required for reducing flood impacts. One possibility to be done is to build a new retention and detention ponds in the UGM area as an addition of the existing retention pond. In line with the UGM plans to become an educopolis campus, a multipurpose detention pond is more suitable, which also can serve as a means of learning, sports and recreation. Hydrologic analysis that consists of hydrograph inflow and routing through the pond at certain return periods were done by using HEC-HMS software. The analysis showed that the addition of an existing retention pond, a new detention pond is only able to reduce the 2 and 5 years flood return period up to 28. 4% and 22. 3%, respectively. The simulation result indicates that despite construction of both detention and retention ponds, flooding still occurs downstream due to small size of the ponds and small carrying capacity of the river. However, during dry season or low water flow, the retention and detention ponds may give additional advantages such as for raw water sources, recreation and sport as well as outdoor lectures
Year: 2017