Hydraulic model of dam bengoh for flood mitigation in Sarawak kiri river

• Main Author: Ryan, Hardin
• Format: Final Year Project Report
• Language: English; English
• Published: Universiti Malaysia Sarawak, UNIMAS 2010
• Subjects: T Technology (General); TD Environmental technology. Sanitary engineering
• Online Access: http://ir.unimas.my/id/eprint/7772/1/Hydraulic%20model%20of%20dam%20bengoh%20for%20flood%20mitigation%20in%20Sarawak%20kiri%20river%20%2824pgs%29.pdf; http://ir.unimas.my/id/eprint/7772/8/Ryan%20Hardin%20ft.pdf; http://ir.unimas.my/id/eprint/7772/
• Institution: Universiti Malaysia Sarawak

Sarawak Kiri River had experienced a disastrous flood event during 9th – 13th January 2009 while Bengoh dam is still under construction. The proposed Bengoh dam had been suggested as a water supply dam which also functions secondarily as flood mitigation measures to reduce the flooding effects along the Sarawak River. The proposed Bengoh dam is 3.25km upstream of Kampung Git, with crest level at 77.5m; it is designed to retain a significant volume of water from upstream, thus retaining flood water from discharging through Sg. Sarawak Kiri. The main purpose of this project was to review the ability of Bengoh dam to mitigate flood water by rerunning the January 2009 Flood event with the inclusion of Bengoh dam. Sarawak River and its floodplains were modelled using one-dimensional hydrodynamic modelling approach, by utilising the Wallingford Software model – InfoWorks River Simulation (RS), coupled with its embedded GIS applications, to obtain the flood hydrographs of the river and its floodplains in the extreme flooding condition of January 2009 flood. InfoWorks RS was applied at Sarawak River from upstream end of Sarawak River Kanan and Bengoh dam’s reservoir to downstream end at barrage. Results demonstrate that InfoWorks RS model is satisfactorily capable of providing a clear picture of the January 2009 fllod event being simulated, highlighting floods where the floodwater flows outside the river channel and its pattern of spread. Simulated locations at Batu Kawa, Sg. Maong and Grand Margarita Hotel were then used as comparison points of before and after inclusion of Bengoh dam for studying its effects. Modeling of Sg. Sarawak with Bengoh dam showed that it is able to retain floodwater and reduce discharges, thus reducing flood level.