Rapid Flood Inundation Modelling - Heriot-Watt University

designpadAI and Robotics

Dec 1, 2013 (3 years and 6 months ago)

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Gareth Pender

Institute for Infrastructure and Environment

A New Flood Inundation
Modelling

Heriot Watt University




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.

Contents


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).


1.2: Requirements for an RFSM


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 constant extra head (source:
Krupka et al. 2007)

An example of pre
-
calculation process

Minimum
Depth
(Dmin)

Minimum
Cell Plan
area (Amin)

Water level (m)

Volume (cubm)

1.3 Basic RFSM algorithm

DTM grid
cells

RFSM
flood cells

Real
Floodplain


Rules to provide accurate prediction:

(1)
Water will spread from high location to lower locations (one directional
or multiple directional spilling algorithms) with merging process.

(2)
Dynamic Driving head based on inflow hydrograph

(3)
Floodplain area with a high roughness uses a high driving head


t

discharge

Area 1 =


Area2

Area 2

1.5 Our improved RFSM

Fig.

Inflow Hydrograph

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


1.8 Compare RFSMs with ISIS2D

Maximum velocity using
ISIS2D

Average Maximum velocity
for 17 regions using ISIS2D

Average Maximum velocity
predictions for 17 regions
using our proposed model

The conceptual model parameter
C was calibrated
using one
ISIS2D simulation with peak inflow value= 150cubm/s for
inflow hydrograph.

2.2 Performance Comparison of the conceptual
model and ISIS2D

2.4 Application to Thamesmead, London

Thamesmead 2m resolution grid digital elevation data and


inflow hydrograph.

(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


2.5 Performance Comparison of the conceptual model and TUFLOW

(1) Test more locations.

(2) Fast Rapid flood spreading Modelling using
Cellular
Automata.




Future work

Thank you!