Author Topic: Initial surface elevation  (Read 1896 times)

Dan

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Initial surface elevation
« on: April 21, 2014, 09:43:17 am »
Hi~
Does anyone know exactly meaning of the initial (water) surface elevation in MIKE21?

i.e) Surface elevation ranges are between 30 and 75(el.m)

      1) I entered 0(el.m) for contant initial surface elevation. And then coupled with .mdb file in mike flood.
          As a result --> Occured abnormal terminated errors

      2) I entered 75(el.m) for contant initial surface elevation. And then coupled with .mdb file in mike flood.
          As a result --> Normally terminated, but too much H water depth

H water depth results seem to depend on the initial surface elevation.

Thanks.
Hello~
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Jonas Althage

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Re: Initial surface elevation
« Reply #1 on: May 06, 2014, 02:17:21 pm »
Hi Ordan,

If you put in 0 in your model as initial surface elevation, you'll get a starting point where you have no water depth, as 0 is lower than your bathymetry values.
If you put in 75, it means that the initial water level is located at +75 m. That gives you a maximum water depth of 45 m according to your setup (75 - 30 = 45).

You should chose 0 as surface elevation I believe, if you just want to get your model started (and not do a hot start). If you need to have water in some areas (e.g. lakes), then you need to define a custom initial water level file to use. You can do this by changing from constant to varying initial conditions.

There is probably something else wrong with your model though, the termination is not necessarily connected to the initial condition.

Best regards,
Jonas
DHI Sweden
Water Resources

MiguelSantos

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Re: Initial surface elevation
« Reply #2 on: May 04, 2016, 06:29:55 pm »
Hello Dan (this post is too old but i think it will answer to other people doubts - you have surely solve the question by now),

As you should always have wet boundaries, you should look into your H/Q curve in it.

In order not to let the boundary dry, you could manually add a permanent low depth in it, for instance set for level 30.1 the flow of zero m3/s and combine it with your upper (above 30.15m) H/Q rating curve at the boundary.

In this example, I would choose to start with the initial water elevation of 30.1 m.

This is why I add more terrain downstream and upstream to my "real" domain. That way this simple adjustments won't affect the results in the domain area where results are to be interpreted.

Best regards.