XPSWMM - Neagtive 1D Max water level

[jaypappa]

Hi,

I am wondering if anyone is able to explain why XPSWMM would return negative max water level values in a 1D/2D intergrated model, I have checked the US & DS links and it only relates to indiviual links.

Cheers

[swmmer]

This message means basically that the flow out of a cell exceeded that of the cell volume and the inflow to the cell. So this is a negative volume which is not possible. If this happens a lot the model will stop as it has become unstable. Typically in the Classic solution the fix is to use a smaller time step. If that does not remove the issue then inspect the terrain and the initialization of the model in that area.