Flood risk studies for Jakarta, Indonesia

• Main Author: Lee, Choon Long.
• Other Authors: Lo Yat-Man, Edmond
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Environmental engineering::Environmental protection
• Online Access: http://hdl.handle.net/10356/53841
• Institution: Nanyang Technological University

A 1D flood model was to be developed for Jakarta city using HEC-RAS 4.1 and ArcMap 10. Within the study, areas with no inundation terms as “gaps” were spotted in the inundation maps and the problem was identified to be caused by the cross section line used in ArcMap. A focused study on the overlapping effect of the cross sections was thus carried out. The finding showed that the effect of the cross section was most affected in the horizontal direction than the vertical direction (in between two cross sections) which will be further elaborated in the report. Evetually, the gaps were closed successfully which produced a full inundated map. Also, the effect of adjusting river cross section width with respect to the change in river depth and inundation map was studied. The cross sections data were modified in a way to mimic a smooth and natural shape of the river. A total of 3 extensions were made: 20m, 50m and 100m all evaluated using a 24 hour intensity rainfall event. Results showed that river water depths were not drastically affected throughout the 7 rainfall profiles (2-year, 5-year, 10-year, 25-year, 50-year, 100-year return period and 2007 Jakarta Flood). It was narrowed to two possibilities: water depth affected by the sea water level and high flow rate in the river. The inundation maps were also not representative of the actual flood in some areas due to the limitation of the 1D model which resulted in inundation at locations which were not supposed to be. This could be a major finding that highlights the limitation of 1D model.