2D Modeling of Urban Flooding


 Product(s):CivilStorm, SewerGEMS
 Version(s):CONNECT Edition
 Area:Modeling

Problem

How can I model a "2D simulation", showing the extent of flooding / overflow above the road curb? For example when overflow spills over a gutter and into the surrounding area, I want to see how far the flooding extends.

Can we see this urban flood map in 3D to know the "spread" of runoff extending beyond the road?

Solution - 2D Modeling in SewerGEMS and CivilStorm

Starting with CONNECT Edition Update 4, 2D Modeling is available directly inside SewerGEMS and CivilStorm, at no extra cost for subscribers. This enables a tight integration of the FLOOD solver so that you can perform 2D and coupled 1D + 2D simulations without having to use multiple software packages. See more here: 2D Modeling in SewerGEMS and CivilStorm

Solution - FLOOD Integration

For those who do not have access to CONNECT Edition Update 4, a 2D simulation can also be accomplished with OpenFlows FLOOD (formerly known as MOHID Studio from ACTION Modulers - does not use Bentley licensing, contact Support for a license key). Existing SewerGEMS/CivilStorm models can be imported and combined with a terrain surface to perform a 2D simulation of a hydraulic model. A separate article with details will be available soon. If you are interested in OpenFlows FLOOD, please contact your Bentley Account Manager. See more details here: Integrating SewerGEMS or CivilStorm with OpenFlows Flood for 2D simulations

For typical SewerGEMS or CivilStorm simulations, usually this level of detail is not needed, as you would typically want to be alerted to cases where the top of the gutter is exceeded and then address the problem accordingly. You can check to see (using a query or color coding for example) if the calculated gutter depth exceeds the depth over which water would reach the top of the gutter (or middle of road) and "spill" over to the other side. If the depth reaches this value, you would likely need to take some action, or note that it is a problem area in your drainage system.

Within SewerGEMS or CivilStorm, you can also perform quasi-2D modeling using a network of 1D channels and/or ponds. The downstream trace query can show you where overflows would flow on a terrain model. Once you know that you can set up channels along the flow paths to analyse the flows. 

Another approach, for catchbasin overflow, would be to use the Ponded Area option for the catchbasins' "Surface Storage" option. However, this can be challenging for the numerical solver. Some of these challenges are described here: Modeling surface ponding for overflow above multiple inlets

See Also

Integrating SewerGEMS or CivilStorm with OpenFlows Flood for 2D simulations

Flood Modelling using SewerGEMS

Digital Terrain Models and Downstream Trace

Modeling surface ponding for overflow above multiple inlets