Posted Wed, 01 Oct 2014 23:55:22 GMT by Alireza Vahidi
I have a couple of Questions. I appreciate if some one can help me.
1-There is  an option in Hec ras (Levee)  which let designers to confine flow in specific part of river bed, Is there such option in Mike 11 as well? How can I model levee in Mike 11? (I have attached a screen shot from Hecras to make it more clear)
2-How can I adjust the number of iteration in MIke 11? what number of iteration do you normally choose?
3-Is there any way to remove all interpolated cross sections together?
Posted Thu, 02 Oct 2014 09:45:12 GMT by Mathieu Hellegouarch
Here is some information regarding your questions:
1. You can very easily apply marks in all cross-sections: mark 1 represents the left end of the active area, and mark 3 the right end of this area. So, the parts of the cross-section which are located to the left of mark 1 or the right of mark 3 are not used in the simulation (just like if there were very high vertical walls above these marks. This is very convenient if you need to exclude a part of a cross-section when you know it won't be flooded.

In case this side part of the cross-section is to be flooded at some point in time during the simulation (e.g. a storage area during a flood event), you therefore need to describe this additional area with another calculation point. You can for example use a link channel (describing an overbank spilling) with the storage area located downstream this link, or you can use a second branch to model the flow through the side part of the cross-section (this second solution is relevant if you need to model parallel flows, e.g. in the main riverbed and in the floodplain). In both options, you get two different calculation points for the same cross-section, which will give you different levels in the main part of the cross-section and in the side part.

2. I suppose the number of iterations you're looking for is the parameter 'NoIter', available in the 'Default values' tab in the *.hd11 file. The default value of 1, which means that MIKE 11 performs 1 additional iteration after the default calculation (or 1st iteration), is usually suitable.

3. There is no easy way to remove all interpolated cross-sections at the same time. If you have much more interpolated cross-sections than 'real' surveyed sections, you can consider doing the following: select the cross-sections you want to keep, export them to a text file (File > Export), delete the whole river branch, import the saved cross-sections (File > Import) again.
If you simply added the interpolated cross-sections to get a finer resolution (with additional computational points), you can simply use the 'Maximum dx' parameter instead. This parameter is defined in the branch properties, and defines the maximum distance between calculation points for each branch. The necessary additional computational points are added at run time only, and hence it is extremely easy to revert back to a coarser resolution if needed.

I hope this is clear, otherwise just let us know.

Best regards
Posted Mon, 06 Oct 2014 12:38:51 GMT by Alireza Vahidi
Hi Mayhieo,
Firstly I appreciate your complete response.
I have some more questions I appreciate that if you can answer my questions.

[b]Case 1[/b]

[b]1[/b]-If I have a river and a floodplain (Along each other) How can I use link channel to connect river and floodplain? (There is no structure separating  the river from the floodplain (Floodplain connected to river through natural terrain) and flood plain is perform as storage,I have attached the the jpeg file to make it clear).
I have done this procedure:
[b]1[/b]- First I established the river network and cross sections.( Just the main river without the floodplain)
[b]2-[/b] I made another branch with just two nodes (Change it to link channel in tabular view) and connect it to main branch with connect branch tool( Is it correct?)
[b]3[/b]- To define the linked channel  I chose spill elevation  as upstream bed level and floodplain first point elevation as down stream level. I chose the Width of terrain (High ground) which separate main river from floodplain(4 meters in this example)

[b]Question 1[/b]: Is there any limit for the length of linked channel? what if river and floodplain is divided with just 1 meter high ground?
[b]Q2[/b]: How can I insert linked channel geometry into the program? (I mean for irregular geometry (Natural terrain) there is no option for plotting the geometry!
[b]Q3[/b]- what should I do if floodplain stretch long distance along river side ? should I define multiple linked channels? or it is better to use mike flood?

[b]4[/b]-  Then I chose additional storage at the end of linked channel
[b]Question[/b] : where can I insert the storage elevation  curve in to mike11?


In case of existence of levee or vertical wall (Short width: less than 1 m) should I use weir(side structure with reservoir) ?
Is there any option to plot  weir( side structure) along the river? whenever I click plot option, it just plots upstream and down stream cross section!)
doesn't it t need to insert the end chainage of  side structure? Does mike 11 calculate it based on width which we have defined in geometry section (level-width)?

[b]Thanks in advance.


Posted Thu, 09 Oct 2014 16:20:22 GMT by Mathieu Hellegouarch

Regarding case 1 : the way you proceeded seems to be correct.
For question 1: there is no numerical limit for the length of link channel
Q2: I'm not sure what you refer to when you mention the link channel geometry. If you refer to the bank / spilling elevation: this is specified in the 'Cross section geometry' options, and describes the geometry of a weir describing the bank.
Q3: Yes you should define multiple link channels: that will allow for a better description of the spilling level along the river branch, and will also allow taking into account the water level changes along the river. You could use MIKE FLOOD instead, which will be usually better because it may use a fully 2D approach for the floodplain. Using MIKE FLOOD is also sometimes even easier than setting up a high number of link channels.
Q4: when applying a storage on a link channel: you have to add a cross-section at the location of the storage (upstream or downstream end of the link channel) and define the Level / Storage area in the processed data of this cross-section (by use of teh Additional Storage Area column). If you use the link channel to model the spilling over a single location, into a reservoir, it may be easier to use a side structure (weir type) with reservoir, which is easier to set up.

Case 2: using a side structure or a link channel is basically the same, except that when using a weir you can select which weir formula you want to use. And when using a side structure weir, the Plot button can only display the upstream and downstream cross-sections, even for a side structure!
The end chainage for a side struture will allows use a default value, so it's not based on the geometry.

Best regards,
Posted Sat, 11 Oct 2014 23:29:38 GMT by Alireza Vahidi
Hi Mathieu,
Firstly thanks for your response.
Then, I have more questions. I appreciate that if you take look at these.
In Mike 11 user’s  guide is mentioned that no cross sections are required  in link channel (page 64- Mike 11 user guide 2009)  instead  we can use [b]edit link channel parameters[/b] in tabular view and insert cross section geometry(depth-width table.) But I think you suggest that(If I am not wrong) defining a cross section at the beginning of link channel as the bank spilling elevation and cross section at the end of link channel to represent the storage.
I think (If I am not wrong) these link channels don't really exist (The river spills along it's bank not from specific points) we just assume these channel link to be able to model the spillage in 1d.  Now my question is that how can I find  the best link channel geometry? should it be rectangular? How long should be the width of link channel?  if I have to put a cross section at the beginning of link channel, should  it be the same as river bank longitudinal profile at that  chainage? (For example  river bank longitudinal profile  from chainage 5000 to 5005)what should be the bed resistance  and  head loss Coefficients?(There is no suggestion in user manual)
Best regards.

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