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 David Jud (Davidjud) posted on Wednesday, June 03, 2009 - 09:00 pm
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1) modelling in reach mode, how far to the left and to the right of the river should the DEM be available. is there a rule of thumb?
2) Do I need the bedrock file for reach mode?
3) Do I need a file with soil layers in reach mode?
4) Timestep and duration of input hydrology (and sediment): the intended simulation time is 10 years. does my input hydrology and sediment file have to cover all of the ten years (with 2 or 3 bed building flood events) which means 87'000 lines (if a timestep of 1 hour is chosen)?
Thanks for looking at my (beginner) questions!!! |
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Hi Dave,
1. Ok, it depends how wide you might expect the river to widen to... there is no rule of thumb, I tend to use the whole valley floor - up to say a terrace edge. You could for example go for 4-10 channel widths either side?
2. It depends - bedrock stops incision.. so if you want part of your reach not to erode (e.g. if its representing bank protection) then make the bedrock DEM the same elev as the main dem.
3. No - it will generate the soil layers with the size distributions that are in the sediment tab.
4. Yes! I think the downtimes (recovery times) can be as important as the flood times!
Hope that helps,
Tom |
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| David Jud (Davidjud) posted on Thursday, June 18, 2009 - 01:47 pm
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Hi
I have again a question to my q 4) above. I intend to simulate now 28 years because that's the timespan i have data from the past. So has anyone experience with using CAESAR with such a large amount of data (i use hourly discharge and sediment data, which gives a file with over 245'000 lines).
Is it possible to simulate the whole sequence or should i start with aggregating the data and using only the flood events.
Cheers
David |
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Well, you can use daily inputs - and in the hudrology tab there is a box for the input time step. This would cut down the size of your file.
Or yes - you use long files! As long as the PC has enough memory it will work...
Tom |
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| David Jud (Davidjud) posted on Thursday, June 25, 2009 - 08:49 am
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For the simulation of my self widening river, which lateral erosion method do i use best and how are the parameters set?
Thanks
David |
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OK, for now I would leave the lateral erosion - I'm working on this at the moment, and version 6.0 will be more straightforward (and lateral will be better represented).. Hoping to have this out within a week..
Tom |
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| David Jud (Davidjud) posted on Friday, July 10, 2009 - 02:11 pm
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Hello
As I am moving on to modelling the self-widening of the river now (until now I tried to calibrate the model with a known flood event in the channel, I have a few questions:
Bank material:
How ist he bank material (sediment) represented in the model? Should it be given in the grain data file? I’m still using V5.9c as I got more reasonable results using it (with Tao based on velocity). So which lateral erosion option do I choose? In what order of magnitude should my lateral erosion rate be (for gravel like material as bank material)?
vegetation:
How is vegetation being represented. Do I just give the modelt he criticial shear stress for my vegetation and it assumes the vegetation to be everywhere expect for bedrock? What if I have big trees the consolidate the sediment of the banks with their roots?
Would be great if you could (even shortly) answer my questions as I am in sort of a time pressure…
Thanks for any answers
David |
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Hi David.
Bank material will be the same as bed - same distribution of grainsizes. But this will only be a factor for vertical erosion and dep. At present lateral erosion is NOT changed by the constitution of thebank material. THerefore, you have to represent different bank material strengths through the lateral erosion constant... Of course if the bank material is coarse, when a cell is low enough (due to lateral erosion) to be eroded by vertical erosion and deposition then the removal rate of the bank material will be lower.
Similarly, vegetation only influences vertical erosion and deposition.
So, there are two ways the channel can widen. 1 through lateral erosion - and to alter this you change the lateral eroion constand or 2 if the water depths are great enough to inundate the bank cells (or cells at the edge of hte channel) then erosion will depend upon the bank material and the veg strenghts.
FOr some feedback, what were the differences between the old and new versions of the model?
Tom |
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| David Jud (Davidjud) posted on Monday, July 20, 2009 - 09:05 pm
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Hi
I got an error message when doing a simulation with the tao calculation method 2 (based on bedslope).
The error message says: "The index was outside of the array."
The following is all in German but I think you will understand what it may mean.
Informationen über das Aufrufen von JIT-Debuggen
anstelle dieses Dialogfelds finden Sie am Ende dieser Meldung.
************** Ausnahmetext **************
System.IndexOutOfRangeException: Der Index war außerhalb des Arraybereichs.
bei caesar1.Form1.erode_bedslope_tau2(Int32 x, Int32 y, Double depth, Double slope, Double slopesum)
bei caesar1.Form1.erode()
bei caesar1.Form1.erodedepo(Object sender, EventArgs e)
bei System.Windows.Forms.Timer.OnTick(EventArgs e)
bei System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
bei System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
************** Geladene Assemblys **************
mscorlib
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3082 (QFE.050727-3000).
CodeBase: file:///C:/WINDOWS/Microsoft.NET/Framework/v2.0.50727/mscorlib.dll.
----------------------------------------
CAESAR 6.0
Assembly-Version: 1.0.0.0.
Win32-Version: 1.0.0.0.
CodeBase: file://impuls-901/davidjud$/Diplomarbeit/Berechnung_2009-07-18_5/CAESAR%206.0.exe.
----------------------------------------
System.Windows.Forms
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3053 (netfxsp.050727-3000).
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Windows.Forms/2.0.0.0__b77a5c561934e089/System.Windows.Forms.dll.
----------------------------------------
System
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3053 (netfxsp.050727-3000).
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System/2.0.0.0__b77a5c561934e089/System.dll.
----------------------------------------
System.Drawing
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3053 (netfxsp.050727-3000).
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Drawing/2.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll.
----------------------------------------
System.Configuration
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3053 (netfxsp.050727-3000).
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Configuration/2.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll.
----------------------------------------
System.Xml
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3082 (QFE.050727-3000).
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Xml/2.0.0.0__b77a5c561934e089/System.Xml.dll.
----------------------------------------
mscorlib.resources
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3082 (QFE.050727-3000).
CodeBase: file:///C:/WINDOWS/Microsoft.NET/Framework/v2.0.50727/mscorlib.dll.
----------------------------------------
System.Windows.Forms.resources
Assembly-Version: 2.0.0.0.
Win32-Version: 2.0.50727.3053 (netfxsp.050727-3000).
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Windows.Forms.resources/2.0.0.0_de_b77a5c561934e089/System.Windows.Forms.resources.dll.
----------------------------------------
************** JIT-Debuggen **************
Um das JIT-Debuggen (Just-In-Time) zu aktivieren, muss in der
Konfigurationsdatei der Anwendung oder des Computers
(machine.config) der jitDebugging-Wert im Abschnitt system.windows.forms festgelegt werden.
Die Anwendung muss mit aktiviertem Debuggen kompiliert werden.
Zum Beispiel:
<configuration>
<system.windows.forms>
</configuration>
Wenn das JIT-Debuggen aktiviert ist, werden alle nicht behandelten
Ausnahmen an den JIT-Debugger gesendet, der auf dem
Computer registriert ist, und nicht in diesem Dialogfeld behandelt. |
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Thanks Dave,
I think this is the same error I found today after Jorge pointed it out.
Tom |
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| David Jud (Davidjud) posted on Thursday, July 23, 2009 - 05:26 pm
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Vegetation question again.
Hi
You wrote in your last post that vegetation influences vertical erosion and deposition.
How does it work?
1) Does the model assume grass cover all over the model except for the bedrock area?
2) If the calculated shear stress in one cell is lower than the value given in the vegetation tab, no erosion is taking place?
3) What's the deal with the grass maturity? Does it influence the growing of new grass during the simulation (there is also the "Grass now" button)?
Thanks
David
Here is a nice picture of my self-widening river:
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OK. The veg rules are:
1. Veg will grow anywhere were there is NOT Water. It will grow on 'bedrock' but that doesnt matter as bedrock cannot erode anyway..
2. It grows from 0 to 1 at the rate in the box on the veg tab.
3. Once the veg value is greater than 0.5 then it prevents erosion of sediment in that cell.
4. The veg value is reduced (in proportion to the shear stress) when the shear stress of the flow over the veg exceeds a threshold (set in the veg tab). So if veg is completely mature (value 1) it will 'erode' until less than 0.5 when you will start to get erosion of the sediment below.
5. Veg also has an elevation. So if it is buried, sediment ON TOP of the veg can be eroded down to the veg elevation. Also, if buried the veg will gradually grow back to the surface
6. But veg will also die back at a rate if buried - so if buried by alot of sediment (e.g. 0.5m) then it will die and re-grow on the surface.
7. Veg also dies back at a rate if it is under water (I think 2* the growth rate).
8. Finally, if veg is undercut (e.g. lateral erosion erodes a bank) then it will die - and then start to grow back again at the new cell elevation.
9. Finally again! then grass now button - when pressed sets the grass values to 1 and the grass elevation to the cell height for EVERY cell in the domain that does NOT have water on it. So you can run the model with a discharge that fills the channel - then press the button and it vegetates everywhere.
Hope that helps, and thanks for the picture. .. Is it working OK?
Tom |
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