Dear HEC-RAS Community,
for my thesis I am modelling embankment dam breaches at canals (commercial inland waterways) for different study cases to generate hazard maps and compare the results of HN-modeling with the results of provisional risk assessments.
The models are built quite simple:
– 2D-Area for the canal as reservoir (“canal”)
– 2D-Area for expected inundation area (“area”)
– SA/2D Connector as Weir with Breach Plan
– DEM with integrated buildings (+3 m) and the canal (- x; calculated from Volume/area relation); 1m Grid resolution
– Landuse as shapefile with ~20 different groups
Initial Conditions for Unsteady Flow:
– “canal” was set with an initial water level at around 3.70 m
– “area” with water level 0
After solving some instability problems and finishing the model run, I experienced something strange: The water level in “canal” was rising during the model while also some flow into “area” took place. At the end of the 23 hours simulation time the result map shows the water level for the canal at 4.90 m.
As I’ve set no boundary conditions since I look at the “canal” as just a reservoir (due to locks there is almost no in/outflow happening) this basically means, that the model produced water out of nowhere.
What could possible reasons for this behavior be? Only “error” during computation was has a weir breach lower than the cells they are connected to for 2D Area “area”. But I’d expect that in this case some water will remain in the canal as soon as the water level will be equal to the cells.
Help, hints and tipps are much appreciated, since I’m getting closer to the deadline for my thesis.
Cheers
