WRF-Hydro negative streamflow

[Jana Corominas]

Hello everyone,

I have run many times wrf-hydro, but recently I'm modeling a new basin and found a strange behaviour in the streamflow values. In the attached image you can see the channel grid with streamflow values. Yellow cells correspond to negative streamflow! This behaviour is repeated in many stream connections from tributary rivers to the main ones, and also in random cells in the middle (but not so frequent). 

Has anyone encountered this problem too? How can I solve it?

I used a burned DEM (negative values in the channel grid) as input data to the GIS preprocessing tool to achieve a better definition of the channel grid (which looks fine). 

Thanks a lot!

[aubrey]

Hi Jana:

Negative flow (backwater) is possible in the diffusive wave gridded channel configuration. If it is occurring when/where not expected, you might check your routing timesteps to make sure they are reasonable for your grid spacing. There is guidance for these settings in the user guide.

Thanks!

Aubrey

[Jana Corominas]

Hello,

I'm working with a 5 km input meteorological model and DXRT=200 m. It is quite a large basin so I don't need to reduce the grid spacing much. I am using DTRT_CH = DTRT_TER = 12 seconds, is it appropriate? I am not sure how to configure these two timesteps accordingly, any advice would be appreciated.

Thanks