Modelling of Flood Inundation due to Levee Breaches: Sensitivity of Flood Inundation against Breach Process Parameters

Abstract

This paper analyses the sensitivity of flood inundation due to river levee breach against breach process parameters using the 1996 Awash River levee breach case at Wonji, Ethiopia. A parametric levee breach model integrated into the 2D hydrodynamic numerical model Telemac-2D is used to simulate a levee breach flood event at Wonji, Ethiopia. Levee breach process parameters are systemically varied to find out their effect on the flood inundation. The analysis of the model results shows that the flood inundation is sensitive to the final breach dimensions and breach location. However, the parameters describing the levee breach development have negligible influence on the flood inundation. This implies that final breach dimension and breach location in an event of levee breach are the most important and decisive parameters affecting the resulting inundation of the flood plain, and as such should be given due consideration when creating flood inundation maps due to levee breach.

Uncertainty Assessment of Flood Hazard due to Levee Breaching

“…The 2D depth-averaged hydrodynamic model TELEMAC-2D, from the TELEMAC-MASCARET hydro-informatic system (www.opentelemac.org), is used to simulate freesurface flow using the finite element method on a triangular element mesh [40]. TE-LEMAC-2D has been widely applied for simulating flood propagation induced by levee breaching [28][29][30][31][32][33][34][35][36][37][38][39][40][41]. The mesh composed of 311,112 nodes is elaborated from breaklines so that topographic singularities (e.g.…”

“…Simplified models describe the levee breaching by making assumptions on the location, initiation, development, number, and shape of the levee breach, often based on engineering experience, and knowledge of historical events [28]. In the present study, breaches are initiated at pre-defined locations (Figure 1-(a)), identified from historical observations [46][47] and field survey.…”

“…The levee breach modelling ranges from simple empirical equations [26] to complex models solving coupled system of shallow water equations and sediment transport formula [27]. For practical modelling of flood inundations caused by overtopping flows induced levee breaching, parametric breach models are a suitable approach [28], describing the breach expansion by simplified equations. Since breach behavior is highly dependent on the geometrical and geotechnical characteristics of the levee, there are uncertainties with regards to the breach initiation and development processes [29].…”

Real-Time Flood Mapping on Client-Side Web Systems Using HAND Model

“…In this study, we evaluated the computational performance of client-side flood map generation using the HAND model and WebAssembly. We selected different DEM resolutions (1,5,10,25,50, and 100 m) and grid sizes (1,4,9,16, and 25 million cells) for evaluation. Based on the selected elevation data resolution and grid size, generated maps represent city, county, and state scale in coverage (Table 3).…”

“…Of natural disasters worldwide 40% are floods [2]. It is important to model and predict inundation extent of floods, which is critical information for flood mitigation [3,4], preparedness [5], and planning and response efforts [6]. Real-time and accurate predictions of flood inundation extent can facilitate understanding the potential flood risk and damage [7,8], and support flood mitigation and planning [9].…”