Problem to run software (water surface unstable)

Hi Chris, Maybe you don't remind me, but I am Nancy the girl that came from Canada to your last workshop in June. I have been working in the water quality modeling for the Athabasca River as my thesis project. I am just starting with the hydraulic calibration, but I am having some problems. I have done some research and trials to solve them without success; I hope you can help me. I've set up my river reach (aprox. 800 km) which doesn't have any structure in 4 water bodies and 10 branches (266 segments). Initially, I had the water surface elevation [ELWS] at a higher level than my grid. The pre-processor gave me no errors, but 4719 warnings. Most of the warnings were due to a high wind speed (> 20 m/s). However, there were others for the following reasons: Cell width [B(18,127)=3.100] < 5m which can cause stability problems Cell width [B(6,111)=5.480] < or > 1Ox width [B(6,112)=71.080] water surface elevation difference of 5.60 m between segment 3l and segment 34 I ignored these warnings because they were due to my raw data, and I tried to run the post-processor. However, it was stuck after some seconds (aprox. 1/2 of the progress line). I could observe that in the Branch flow, Branch temperature, Water surface elevation and Minimum deviation sections showed up a NaN value (not a number). I saw the w2.wrn file that was created and it had the following information: Water surface is above the top of layer 2 in segment 22 at day 200.000 Computational warning at Julian day = 200.000 at segment 2 timestep = 3457. 000 water surface deviation [z] = 57.198 m layer thickness = - 56. 288 m Negative surface layer thickness in segment 2 time step reduced to 1.000 s on day 200.000 at iteration O computational warning at Julian day = 200.000 timestep = 0.900 sec I read in the manual that this error can be due to an underestimation of outflows. I checked the pre.opt file, and it says in the water balance section that the total outflows for the water body 1 were zero. I used the Forum to find more information about this problem, but I couldn't solve it yet. However, I downloaded all the software updates available. Running my river model in the updated version gave me the same warnings in the pre-processor, but the w2.wrn file gave me this information: water surface is above the top of layer 2 in segment 2 at day 200.000 computational warning at Julian day = 200.000 spatial change = 0. 10622841E+06 m^3 temporal change — 0. 11155343E+06 m^3 volume error —-0. 53250155E+04 m^3 LAYER CHANGE: F sz -13. 3921318655743 -13. 3921318655743 -14.4776308439698 -14.4841298333502 -14.4 581287787906 -14. 6076279768859 -14. 5166270211914 -12.4821226271932 -12.4821182331952 -12. 4821138391970 -12. 48210944 51988 -12. 4821050512008 -12.4821006572026 -12.4820962632045 -12.4820918692064 -12.4820874752082 -12.4820830812101 -12.4820786872120 -12.4820742932139 -12.4820698992157 -12.4820655052175 -12.4820611112195 -12.4820567172213 -12.4820523232233 The list continues up to … 1. 19319193 5483871E-002 0. 790601500000000 1. 00000000000000 1. 00000000000000 1. 00000000000000 8. 79000000000000 QWD The manual says: "This message is to let the user now that the volume error is more than 1000 m3. This should not normally happen unless the user has incorrectly modified the code or the water surface elevation solution has become uastable. The message is more informational and does not require the user to do anything as the volume error is arbitrarily set to 1000 m3." I didn't modify the code, and I wasn't sure what could make the water surface unstable. I decided to change the water surface values [ELWS] because they were above the grid. I couldn't find criteria to set this parameter and I set this 2m (about two layers) below the Elev-top value of layer 1 for each segment. However, after this the pre-processor gave me 12 errors. These are: No active segments in branch 2 Water level too low in branch 2[CUS(JB)50] connected to branch 1 by downstream head No active segments in branch 3 Water level too low in branch 3[CUS(JB)59[ connected to branch 2 by downstream head No active segments in branch 4 Water level too low in branch 4[CUS(JB)69] connected to branch 3 by downstream head No active segments in branch 5 Water level too low in branch 5[CUS(JB)106] connected to branch 4 by downstream head Water level too low in branch 6[CUS(JB)127] connected to branch 5 by downstream head Water level too low in branch 9 [CUS (JB) 196] connected to branch 8 by downstream head No active segments in branch 10 Water level too low in branch 10[CUS(JB)266] connected to branch 9 by downstream head Once again, I confirmed that there is not outflow in the water body/branch 1. I have also tried to lower the initial water surface even more, and it didn't work. On the other hand, I tried setting all my branches as different water bodies, but it didn't help. I have no clue about what is causing this problem. I will appreciate any guidance and help to understand why there is not an outflow from my first branch?, what are the criteria to set up ELWS?, What is the advantage of setting all the branches as water bodies? Thank you so much! Best regards, Nancy Gutierrez