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Unstable water surface elevation

Sun, 03/08/2009 - 8:40am — m_elshemy
Dear all, please I need your help. I have used W2 to simulate a part of a huge reservoir. I have finished the calibration and it was OK. Now I'm trying to validate the model using a new data set (High discharge and water levels), the model gives a runtime-error as follows: Unstable water surface elevation on day 37.714 negative surface layer thickness using minimum timestep at iteration 49607 Segment, Surface layer thickness, m 199 -0.52 200 -0.52 201 -0.52 I tried to reduce DLTMIN, DLTMAX,and DLTF but no way, the segments and the values of the error may change but the model still stops and gives the same error. Are there Any suggestions? Thanks Mohamed
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Hydrodynamics
Mon, 03/09/2009 - 2:21pm — Qasem Abdelal

Mohamed, High flow values may be causing your instabilities, check the inflow file for high jumps around day 36-37. If indeed you have a high gush of water due to a storm try to gradually reduce the peak and spread the inflow over a longer period. Also check the bathymetry of higher layers, try to smooth it if necessary. Hope this helps.
Tue, 03/10/2009 - 9:23am — m_elshemy

Qasem, Thank you very much for your help and your reply. Really I tried to modify the discharge and the bathymetry but it doesn't work. Finally I found the problem, it was in Branch interpolation I turned it OFF and now it is working. Thanks again Mohamed