1D / 2D Flood Modelling of River Indus: Guddu – Sukkur Reach

Abstract

Floods are one of the worst natural hazards being face by mankind, bring infrastructure devastation and are also responsible for loss of human life. Pakistan, since its creation, has faced the challenge of floods. However, not much has been done in field of numerical modeling and predicting the flood extent / behavior. Basing on availability of good quality topographical data (10m DEM) and hydrological data the reach of Guddu- Sukkur is selected for modeling. In this study an attempt has been made to simulate the major flood event of 2010. Moreover, for the first time an effort is made to resolve a Tori Bund dispute scientifically (a controversy whether the Flood Protection Bund (FPB) i.e. Tori Bund was breached to safeguard interest of local feudal or the bund was overtopped). A 10m Digital Elevation Model (DEM) of the area with +0.5m vertical accuracy is used. The topographic data is used to construct river geometry using ArcGIS and HEC-GeoRAS. 1D steady model using HEC-RAS is run to simulate the flood. A tool in ArcGIS is also used to graphical represent the flood plain delineation including visualization of overtopping of the bund. Unsteady flow 1D & 2D models are run using Basic Simulation Environment (BASEMENT). The recorded water surface elevation (obtained from irrigation department) was then used to calibrate the model and in the course of this research, three GIS software namely ArcGIS, Global Mapper and Quantum GIS, three water resource software’s namely BASEMENT, HEC-RAS & Geo HAC-RAS and two processers’ i.e. BASEmesh and SMS10 are used. 2010 flood simulation on modeled reach of Guddu-Sukkur shows reduced height of bunds verses WSE particularly the downstream of mid reach. The methodology presented in study can be used to simulate flood events for other reaches / river provided that topographic and hydrological data is available.