On the Simulation of Floods in a Narrow Bending Valley: The Malpasset Dam Break Case Study

Abstract

Abstract:In this paper, we investigate the performance of three-dimensional (3D) hydraulic modeling when dealing with river sinuosity and meander bends. In river bends, the flow is dominated by a secondary current, which has a key role on the flow redistribution. The secondary flow induces transverse components of the bed shear stress and increases the velocity in outward direction, thus generating local erosion and riverbed modifications. When in river bends, the 3D processes prevail, and a 3D computational fluid dynamics (CFD) model is required to correctly predict the flow structure. An accurate description of the different hydrodynamic processes in mildly and sharply curved bends find a relevant application in meanders migration modeling. The mechanisms that drive the velocity redistribution in meandering channels depend on the river's roughness, the flow depth (H), the radius curvature (R), the width (B) and the bathymetric variations. Here, the hydro-geomorphic characterization of sharp and mild meanders is performed by means of the ratios R/B, B/H, and R/H, and of the sinuosity index. As a case study, we selected the Malpasset dam break on the Reyran River Valley (FR), as it is perfectly suited for investigating performances and issues of a 3D model in simulating the inundation dynamics in a river channel with a varying curvature radius.

Small reservoirs for a sustainable water resources management

“…The georeferencing allows the identification of areas with the highest presence of small reservoirs to perform a first evaluation on the possible risk assessment and, consequently, to plan more detailed analysis, considering land use and morphological evolution of the territory with respect to the initial situation in which the reservoirs were built (back to over 50 years ago). The importance of having easily detectable data on the map led to the development of a WebGIS system, so the updating, analysis and spatial analysis of database can all be conducted in a high-performance way (Casadei et al, 2018), with the possibility of developing applications to quantify the water resource and risk.…”

Water Level Measurements from Drones: A Pilot Case Study at a Dam Site

“…The cause of lake decline can be due to changing climatic forces and to poor management of the water resources [19][20][21][22]. Among the causes of dam break, we can list extreme rainfall events, which sharply increase the water level in the reservoir (e.g., [23,24]); thus, proper management of the water level in dam reservoirs is of the utmost importance.…”

Experimental and Numerical Analysis of a Dam-Break Flow through Different Contraction Geometries of the Channel

“…Most of previous works simulated the dam-break flow through the Shallow Water Equations (SWEs) [2,[29][30][31][32]. The complete 3D Reynolds-Averaged Navier-Stokes (RANS) equations involving the turbulence modeling can more accurately describe the dam-break wave propagation over complex topography [27,28,33,34]. Recently, 3D VOF (Volume of Fluid) based CFD (Computational Fluid Dynamics) modeling software, such as FLOW-3D (Flow-Science Co, New Mexico, NM, USA) have been widely applied to the simulation of unsteady free-surface flows and also tested on dam-break flows [35][36][37][38][39][40].The present research focuses on the dam-break flood wave propagation over the downstream channel, characterized by abruptly varying cross-sections.…”