[HCL27]

I took a look in RAS Mapper and I did not notice any abnormalities in the maximum extents of the velocity or depths.

I was using a warm up time and ramp up percentage. I turned that off and re-ran the model but the results were the same. I don’t think this is causing the issue but should I avoid ramp up periods in future models? Is there issues with this? I have used them before and have not noticed any issues.

This issue is only occurring in the drainage with the inflow hydrograph. The other drainages in the 2D area with precipitation only, have normal looking hydrographs.

I think the issue is cell size or cell volume related? A smaller size reduces the dip in the hydrograph but the dip is still there. Also when looking at hydrographs in areas with a wider floodplain and smaller depths the hydrograph does not dip as much.

Here are hydrographs taken 1/2 mi apart. The first in a narrow area with large depths and the second in a wider area with shallower depths. You can see a sharp dip in the first plot but not in the second.

[HCL27]

The Percent Error is 0.03992.

Its strange because the hydrograph drops right when the first drop of precipitation falls at 11:30. And the drop is consistently at this time when I check the flow hydrograph at other places along the main channel that has the baseflow.

Here is a hydrograph of a profile line at the upper end of the model.

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