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A New Flood Inundation Modelling

A New Flood Inundation Modelling. Gareth Pender Institute for Infrastructure and Environment. Heriot Watt University . Contents. Introduction to rapid flood spreading modelling-prediction of flood depth and flood extent. A new conceptual model for maximum velocity prediction.

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A New Flood Inundation Modelling

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  1. A New Flood Inundation Modelling Gareth Pender Institute for Infrastructure and Environment Heriot Watt University

  2. Contents • Introduction to rapid flood spreading modelling-prediction of flood depth and flood extent. • A new conceptual model for maximum velocity prediction. • Illustration of application to case studies.

  3. 1.2: Requirements for an RFSM • Short time to run (Typically < 5s) • A good overall agreement of the final water depth and flood extent predictions between SWEM and RFSM. • A good overall agreement of the maximum velocity prediction over a flood cell between SWEM and RFSM. useful for application to catchment scale flood modelling and probabilistic flood risk analysis (e.g. Bayesian Analysis).

  4. Minimum Cell Plan area (Amin) Minimum Depth (Dmin) • 1.3 Basic RFSM algorithm RFSM flood cells DTM grid cells Real Floodplain • Pre-calculation An array of flood storage cells is constructed from DEM • Inundation A specified volume of flood water is distributed across the storage cells. An example of pre-calculation process Volume (cubm) Water level (m) An example of constant extra head (source: Krupka et al. 2007)

  5. Area 2 Area 1 = Area2 • 1.5 Our improved RFSM • Rules to provide accurate prediction: • Water will spread from high location to lower locations (one directional or multiple directional spilling algorithms) with merging process. • Dynamic Driving head based on inflow hydrograph • Floodplain area with a high roughness uses a high driving head discharge t Fig. Inflow Hydrograph

  6. 1.8 Compare RFSMs with ISIS2D Flood extent using ISIS2D after 10 hours Flood extent using MD-RFSM Flood extent using OD-RFSM Water depth of cross section comparison using ISIS2D and RFSMs

  7. 2.2 Performance Comparison of the conceptual model and ISIS2D Average Maximum velocity predictions for 17 regions using our proposed model Maximum velocity using ISIS2D Average Maximum velocity for 17 regions using ISIS2D The conceptual model parameter C was calibrated using one ISIS2D simulation with peak inflow value= 150cubm/s for inflow hydrograph.

  8. 2.4 Application to Thamesmead, London Thamesmead 2m resolution grid digital elevation data and inflow hydrograph.

  9. 2.5 Performance Comparison of the conceptual model and TUFLOW (a): Final water depth after 1hour using RFSM (b) : Final water depth after 1hour using TUFLOW (c): Region average maximum velocity prediction using the new conceptual model (d): Region average maximum velocity prediction using TUFLOW

  10. Future work (1) Test more locations. (2) Fast Rapid flood spreading Modelling using Cellular Automata. Thank you!

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