River Flood Modelling Using SOBEK: A Case Study from Ciliwung Catchment, Indonesia

This case study presents flood management by diverting excess flood water to a neighbouring catchment which has a safe capacity to carry excess flood water. Floods in a river may be happen due to surface and sub-surface runoff during periods of extreme rainfall or cyclone. In this study it was shown that during extreme rainfall event Jakarta city which is located in Ciliwung catchment is vulnerable to flood. The Ciliwung River has been changed in the last 100 years due to unplanned city development and narrowing the flood plain of the river. Flood can be managed by diverting excess flood water to other catchment where it is feasible. In this case study, possible options to divert excess flood at Ciliwung River to a neighbouring catchment were assessed. SOBEK 1D Rural model is used for simulation river flood. From this simulation, different reliable outputs are obtained by analysing the sensitivity of the numerical and physical parameters. Every step of analysis some recommendation and opinions are made for further improvement of this project which included relocation of tunnel, using a weir, construction an open channel, build a seasonal dam etc. Further detail study is required to make a final decision, by assessing river morphology and considering socio-economic and ecological aspect of the catchment. Similar approach can be applied in other catchment to reduce flood vulnerability of that particular area.