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Flood Modelling

Summary of MIKE11/MIKE21/MIKE Flood Advantages and Suitability

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Flood Modelling

Advantages of 1D model (MIKE11) :

• Accurate hydraulic description in rivers/channels which behave pre-dominantly one-dimensional

• Less computational points than 2D model, ie. less CPU time

• Easy to overview and comprehend results

• Automatic access to sub-modules such as the advanced Structure

Operation module and Flood Forecasting module

Disadvantages of 1D model (MIKE11) :

• Flow paths must be known on beforehand in cases where floodplain branches and and link-channels are established

• Generally more effort needed in model schematization than a 2D model

• No detailed results (eg. velocity field) on flood plains

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Flood Modelling

MIKE 11 suitable for projects :

• Where flood duration, flood extent and storage volume are the important issues on the plains

• Where detailed flow pattern, depths and velocity on the plains are not important

• With many different and complicated structures

• Where other problems (water quality, sedimentation, Flood Forecasting) are to be addressed with the same model tool

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Flood Modelling

Advantages of 2D model (MIKE21) :

• 2-D flow simulated dynamically without pre-scribing flow patterns

• Relatively easy to schematise model

• Detailed information on velocity, depths etc. on flood plains

• Good for simulating embankment overtopping over long reaches

Disadvantages of 2D model (MIKE21) :

• Costly in computational time

• Requires fine grid nesting in river branches in order to match MIKE 11 capability (= increased computation time)

• At present some shortcomings on the computation of wave front celerity

• Only simple fixed structures can be simulated

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Flood Modelling

MIKE 21 suitable for projects :

• Where detailed velocity and depth pattern are important

• Where the flow paths are not well defined but of interest

• With significant two-dimensional flows and where a one-dimensional model can not address the problem

• Which deal with local problems

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Flood Modelling

Advantages of MIKE Flood (MIKE11 + MIKE21) :

• Contains basically the benefits from both MIKE11 and MIKE21

• Can be used to exchange information between a larger overall 1D model and a detailed local 2D model (at locations where no hydraulic data exist)

• New detailed 2D areas can easily be introduced and existing ones can be omitted

•Disadvantages of MIKE Flood :

• Two models must be maintained instead of one (but total work is app. the same)

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Flood Modelling

MIKE Flood suitable for projects :

• Where a 2D (MIKE21) description is needed in local areas and where the features of MIKE11 (eg. Advanced Structures, Flood Forecasting) are required elsewhere in the system

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Flood Modelling

MIKE 11

MIKE 21

MIKE Flood

Problem complexity

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Flood Modelling

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MIKE 21

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1D model ?2D model ?1D+2D model ?