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CESI. IMPACT PROJECT Tous Flood Propagation Case Study CESI Numerical Modelling. 4 th Impact Project Workshop Zaragoza, Spain November 3-5, 2004. WP 3.1: Urban flood propagation WP 3.2: Flood propagation in natural topographies. Guido Testa David Zuccalà. CESI.
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CESI IMPACT PROJECTTous Flood Propagation Case StudyCESI Numerical Modelling 4th Impact Project Workshop Zaragoza, Spain November 3-5, 2004 WP 3.1: Urban flood propagation WP 3.2: Flood propagation in natural topographies Guido Testa David Zuccalà
CESI Tous Flood Propagation Test Case
CESI Topographic Data Building of 1982 DTM from CEDEX map
CESI Topographic Data Building of 1982 DTM DAM AREA After dam-break Before dam-break
CESI Topographic Data Building of 1982 DTM URBAN AREA
CESI Input data Mid hydrograph
CESI Input data Manning roughness coefficient (n=0,03 ms-1/3) Orange trees (n=0,1 ms-1/3) Urban area (n=0,2 ms-1/3)
CESI Input data Mesh generation 10 m X 10 m grid
CESI Numerical Model - 1 ONDA2D * - Finite Volume Model for Shallow-Water Equations * developed with the contribution of Ferrara University
and CESI Numerical Model - 1 Shallow water equation - conservative forms: with: F flux vectors; Eand GCartesian components. and with:
CESI ONDA2D - Finite volume method • Finite volume model : • High resolution Godunov-type method (HLLC Riemann solver); • Explicit scheme; • Second order accurate • - in time: Predictor-corrector scheme; • - in space: MUSCL-Surface gradients methods; • Satisfying the Total Variation Diminishing condition: slope limiter MINMOD; • Pointwise treatment of source terms • explicit approach for bottom slope source term; • semi-implicit approach for friction slope source term;
CESI ONDA2D - Application to Tous case
DTM Characteristics and Simulation features Calculation Step Very strong bottom slope Step front wave propagation over dry bed Anomalous results in some cells… Very small depth Mass and Momentum deficit Water depth and momentum is set zeroin such cells Very high flow velocity ONDA2D - Difficulties in the application to Tous case CESI
CESI Numerical Model - 2 FLOOD2D - Simplified Finite Differences Model for Shallow-Water Equations
CESI Numerical Model - 2 Shallow water equation – convective terms neglected:
CESI Numerical Model - 2 Water depth (m) Flooded area Velocity (m/s)
CESI Numerical Model - 2 Test points outside urban area
CESI Numerical Model - 2 Water depth in test points outside urban area
CESI Numerical Model - 2 Water depth in test points outside urban area
CESI Numerical Model - 2 Water depth in test points outside urban area