[Anuga-user] Problem with unrealistically high stage

[Kyle A W. <kyl...@ut...>]

Hi all,

I've been getting very unrealistically high depth/stage values in the
upstream end of my model domain, and I'm not sure how to figure out what is
causing it.

Currently, my model is a river delta with one upstream channel (constant
discharge inlet + reflective BC inside an upstream lake) and a downstream
bay with a constant tidal water level set by a nearby tide gauge (Dirichlet
BC). Even for flows significantly lower than bankfull discharge, the water
is spilling out of the channel and flooding the surrounding landscape in
places that definitely do not normally flood. This happens even if I make
the bed completely frictionless, increase the grid resolution, or start
with different initial conditions.

Is this something anybody else has experienced, and do you have any ideas
for how I might fix it?

The only ideas I have left are that it is perhaps related to (1) the datum
(I am using NAVD88 in the vertical, which I believe differs from the one
assumed by the model, but I wouldn't expect that to matter much over a few
km), (2) slope limiting (which I don't understand well, but it is a very
flat landscape), or (3) the flow algorithm (too diffusive?).

I've attached pictures of the depth and a quiver plot of the flow
velocities for context. Happy to send the code if helpful.

Thanks & best regards,
-- Kyle

*----------------------------------------------------------------------------------------*
*Kyle Wright*
The University of Texas at Austin
Department of Environmental & Water Resources Engineering