Boundary conditions

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Erik Leemreijze

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Mar 28, 2025, 5:38:34 AMMar 28

to Itzï

Hello everyone,

I am fairly new to using Itzï. At the moment, I am using it to simulate the effects of extreme rainfall in a neigborhood. So far, the results look very good.

Right now, I am having some trouble setting up the boundary conditions. In my analysis, the area is a neighborhood in the middle of an urban region, with no river or other open water present. I want the water to leave the model at the edges of the region. As far as I understand, this corresponds to Boundary Type 2. However, I am unsure how to incorporate this into the raster. Should just one cell of the bctype raster have the value 2, should all outermost cells have the value 2, or should all cells in the bctype raster have the value 2?

My next question is whether a bcvalue also needs to be defined in this case, or can it be completely omitted?

Erik

Erik Leemreijze

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Mar 28, 2025, 9:08:44 AMMar 28

to Itzï

I tried the option with the outermost cells of the raster have the value/setting 2. Itzï started the simulation, but after a few minutes I got the following error and Itzï stopped.

WARNING: Error during execution: itzi.itzi_error.DtError: 'dt must be positive (0.0)'