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w2 error

Tue, 03/31/2015 - 12:59pm — Ashmita
Hi, I am getting the following errors- Fatal error - insufficient segments in branch 1 Julian day = 1.87 at iteration 2975 with water surface layer = 3 Minimum water surface located at segment 13 with bottom layer at 2 Any suggestions on where to find help or address these issues. Thanks Ashmita
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Tue, 03/31/2015 - 3:12pm — Amir

The segment gets dry. The outflow /inflow conditions is in the way that there is no water in this segment. check your inflow/outflows. add additional layers to the bottom of the segment with a very small width (e.g 5m) to prevent segment from drying. choose smaller time steps (DLTMAX) or smaller fraction of that (DLTF)
Wed, 04/01/2015 - 12:21pm — Ashmita

Thanks, Amir. i realized that a couple hours after I had posted. I have another question. I am building the model for a very shallow estuary- 1 m deep. The manual says the depth should be around 5 meters, will the model still be stable?
Wed, 04/01/2015 - 3:45pm — Amir

You are welcome Ashmita. It depends on water level fluctuations. If there is a rapid increase/decrease in flow, the water level will change rapidly. If the changes in water level elevation is more than two layers (in one time step) the model will crash. The problem with a shallow waterbody is that the layer thicknesses are small and it is more probable to have such a problem with rapid water level change. Choose small DLTMIN, DLTMAX and DLTF and you are safe. If with all these considerations the model crash in some point, then you need to make the segments lengths smaller.
Mon, 04/06/2015 - 1:23pm — Ashmita

Thanks again. This is really helpful. I did reduce the DLTMIN to 0.1, and the DLTMAX is now at 5 (reduced from 800). The model is still crashing at 2.240- seems the water surface elevation drops very rapidly (see output file below).

Model run at 12:17:12 on 04/06/15
JDAY DLT ELWS T2 U Q SRON EXT DEPTH WIDTH SHADE Gen1 EPI
1.040 5.00 140.53 9.00 0.00 0.36 0.00 0.45 138.41 38.90 1.00 0.000 10.000
1.140 5.00 126.17 8.98 0.03 124.27 0.00 0.45 124.05 38.90 1.00 0.100 9.900
1.240 5.00 114.72 8.93 0.03 111.40 0.00 0.45 112.60 38.90 1.00 0.198 9.802
1.340 5.00 101.03 8.81 0.03 97.59 0.00 0.45 98.91 38.90 1.00 0.293 9.704
1.440 5.00 90.18 8.67 0.03 78.57 87.56 0.45 88.06 38.90 1.00 0.386 9.608
1.540 5.00 80.69 8.51 0.03 76.13 155.96 0.45 78.57 38.90 1.00 0.474 9.512
1.640 5.00 71.22 8.35 0.03 76.14 83.06 0.45 69.10 38.90 1.00 0.557 9.418
1.740 5.00 61.88 8.16 0.04 78.93 0.00 0.45 59.76 38.90 1.00 0.632 9.324
1.840 5.00 51.91 7.94 0.05 78.15 0.00 0.45 49.79 38.90 1.00 0.697 9.231
1.940 5.00 42.24 7.68 0.06 79.03 0.00 0.45 40.12 38.90 1.00 0.750 9.139
2.040 5.00 32.61 7.36 0.08 78.47 0.00 0.45 30.49 38.90 1.00 0.785 9.048
2.140 5.00 22.73 6.93 0.13 79.59 0.00 0.45 20.61 38.90 1.00 0.789 8.958
2.240 5.00 12.80 6.28 0.29 79.70 0.00 0.45 10.68 38.90 1.00 0.740 8.869

Mon, 04/06/2015 - 2:52pm — Ashmita

Hi Amir, I got the model to run without crashing (had to switch off an external structure- outflow was too high). Now the ELWS seems to be increasing- goes from 140 to 359. Any suggestions on what to decrease/eliminate? Thank you again. Ashmita
Mon, 04/06/2015 - 4:37pm — Amir

You have many options to control the elevation. External Downstream Head is one way. Or if you know the discharge values you can use structures or pumps.
Tue, 04/14/2015 - 6:13pm — Ashmita

I am looking for a cdh_br1 sample file. I have 8 layers in the model, and I am looking to set the downstream concentrations for salinity and maybe DO. Thank you in advance.
Fri, 04/17/2015 - 1:47pm — Amir

Hi Ashmita. The sample file for cdh file is available in "Columbia Slough Estuary" folder in example "folder".
Tue, 07/28/2015 - 12:16pm — Elnaz

hi.my model reservoir has 3 branches with 2 water bodies. Branch 1 and branch 2 are in reservoir (first water body) and branch 3 relate to estuary below reservoir in the second water body. Branch 3 is just for defining spillway to model. At first model I had an unstable elevation of water surface . When I reduced [DLTMAX], [DLTF], run-time error has been occurred and I could not solve run-time error. What are your suggestions to solve these kinds of errors?
Tue, 07/28/2015 - 3:49pm — Amir

Hi Elnaz, I need more information to help but at the moment I can suggest you check the DLX lengths. I suppose you may have some very small DLXs in your bathymetry file. It is not good to have a small DLX in one segment and jump to a long one for the next segment. The bigger the DLX values the better. Also turn off the interpolation for inflow, structure and etc.