# How is ponded depth calculated when an inlet has a local depression

How is ponded depth calculated when an inlet has a local depression

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• Christian, based on your recent product usage I assume you are asking about OpenRoads Designer. When you say "ponded depth" are you referring to the use of the surface storage option with the Implicit or Explicit (SWMM) dynamic solver when using a CivilStorm or SewerGEMS license, or are you referring to the gutter depth result when using inlets with the GVF-Rational (StormCAD) solver?

For the former (surface storage), see the following articles which explain that the flooding depth result is measured from the catchbasin rim elevation:

For the latter (StormCAD/gutter depth), the following article explains that the gutter depth result is measured from the bottom of the local depression (but not for FlowMaster): Where is the Gutter Depth measured from?

As Karl mentioned, the way that the depth is calculated is documented in the HEC-22 equations and in the help documentation. We also have several wiki articles for certain situations (combinations of inlet type and other factor) that explain more about the calculations.

Regards,

Jesse Dringoli
Technical Support Manager, OpenFlows
Bentley Systems, Inc.

• Christian, based on your recent product usage I assume you are asking about OpenRoads Designer. When you say "ponded depth" are you referring to the use of the surface storage option with the Implicit or Explicit (SWMM) dynamic solver when using a CivilStorm or SewerGEMS license, or are you referring to the gutter depth result when using inlets with the GVF-Rational (StormCAD) solver?

For the former (surface storage), see the following articles which explain that the flooding depth result is measured from the catchbasin rim elevation:

For the latter (StormCAD/gutter depth), the following article explains that the gutter depth result is measured from the bottom of the local depression (but not for FlowMaster): Where is the Gutter Depth measured from?

As Karl mentioned, the way that the depth is calculated is documented in the HEC-22 equations and in the help documentation. We also have several wiki articles for certain situations (combinations of inlet type and other factor) that explain more about the calculations.

Regards,

Jesse Dringoli
Technical Support Manager, OpenFlows