Use of HEC-RAS 2D in flood extent mapping for a sub-basin in Jakarta
Cheah, Gerlyn Zhi Ning
Date of Issue2018
School of Civil and Environmental Engineering
Institute of Catastrophe Risk Management
A flood occurs when land that is usually dry gets substantially submerged by an overflow of water. Floods can be hazardous sweeping all in its pathway downstream. Due to climate change and urbanization, floods have been taking place globally with frightening regularity. To better model and plan for such flooding events, the HEC-RAS software is a River Analysis System developed by the U.S. Army Corps of Engineers that models hydraulic calculations for a full network of man-made and natural channels for water flow. In-depth exploration of the difference in HEC-RAS 1D and HEC-RAS 2D can greatly boost the development of a flood simulation model towards a fully integrated flood simulation to assess damage. In this study, HEC-RAS 1D and HEC-RAS 2D were used to map for steady and unsteady flow simulations that were benchmarked to the 2007 flood event in Jakarta, Indonesia, focusing on Sunter River. The effective use of levees in HEC-RAS 2D to correctly mimic the real-life situation in Jakarta, Indonesia was also used in the modelling. It is found that when comparing a steady flow simulation vs an unsteady flow simulation, as the unsteady flow simulation gives an advantage of being time dependent, it is more realistic to use an unsteady flow simulation. However, if the flood in question has a very short flood time, a steady flow simulation is sufficient. It is also concluded that comparing a 1D and 2D flood simulation, 2D gives a better understanding when mapping an urban landscape as features such as levees can be included. 2D also allows for a wider area to be mapped and is not limited to only the river channel. However, 1D model would be suitable if the flow maintains primarily uni-directional flow patterns and elevation data is available of only limited quality and/or quantity.
Final Year Project (FYP)
Nanyang Technological University