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Quasidistributed modelling


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It is possible to create a distributed rainfall depth coverage to assign the rainfall depth to a grid in ModClark simulations?

How can I manage to create it?

We are using WMS 8.1.



Hi Rita!

You can certainly use WMS 8.1 to assign rainfall depths to a grid for MODClark. However, you don't do it using a coverage. As long as you've created a grid on your watershed and you've set up HMS to use a ModClark Transform (HEC-HMS | Edit Parameters), then you can go into the Meteorological Parameters dialog (HEC-HMS | Meteorological Parameters...) and set up a precipitation method of either "User Hyetograph" or "Gridded Precipitation." This is somewhat misleading because if you choose "user hyetograph" and enter a depth and temporal distribution, WMS will use that to create a ModClark rainfall grid. Choosing "Gridded Precipitation" lets you import radar rainfall grids.

If I were you, I would also run through the tutorial labeled "Using NEXRAD Rainfall data in HECHMS (MODClark) Model" in volume VI of the WMS 8.1 tutorials. This tutorial has you set up MODClark rainfall grids using both a user hyetograph and radar rainfall grids.

Good luck!


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Hi Clark.

We are trying to model some basins with ModClark method and we are having big troubles.

The first step we want to solve is the comparation between Clark and ModClark method.

We are trying to simulate the same basin with the same conditions (CN constant, same rainfall gages and depths...) and we are not able to obtain similar results with both methods.

Some questions about it:

1. We leave Impervious (%) =0 in the lumped model. Is it right?

2. We use routing method (Musking Kunge) with the lumped method. Do we have to use a routing method with the quasidistributed model or is it not neccesary?

3. Is possible used the quasidistributed model with subbassins?

Can you give us an example or tutorial where both methods are compared?

Thank you very much.


Edited by Rita
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  • 2 weeks later...

Hi Rita -

I'm sorry to hear you're having problems with your models. Unfortunately, we don't distribute any tutorials that compare the Clark method with the ModClark method. We could certainly help you answer your questions though, but now we're getting into actual modeling principles instead of general software support, which is what we provide through the forum. If you would like some consulting help, please let me know and I would more than happy to discuss it with you.

Thanks and good luck!

Clark Barlow


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