HydroCAD Stormwater Modeling - Since 1986

Agency Acceptance of HydroCAD

HydroCAD provides a range of widely accepted hydrology and hydraulics calculations including:

* SCS Unit Hydrograph runoff (as in TR-20)
* Santa Barbara Urban Hydrograph (SBUH)
* Rational method
* TR-55 Tc calculation procedures
* Storage-Indication pond routing
* Standard hydraulics calculations
* Muskingum-Cunge reach routing

By employing these industry-standard techniques, HydroCAD is well suited for most applications where the SCS TR-20 or TR-55 methods would normally be used.  Please see the comparison table for details.  Given the same input data (along with the selection of the same calculation methods) HydroCAD can be expected to produce similar results to the SCS/NRCS programs.

Due to this consistency of method, design and analysis, work performed with HydroCAD is commonly accepted by any agency or reviewer that would normally accept a study performed with TR-20 or TR-55. Since its introduction in 1986, HydroCAD has met with wide acceptance by reviewers that understand and accept these techniques, and a growing number of localities, like Saint Paul Minnesota, and Santa Barbara County (Letter of acceptanceare using HydroCAD to review all project submissions. 

Only a few agencies have a specific review process for hydrology software.  The Saint John's River Water Management District (Florida) is one example of an agency that has specifically reviewed and accepted HydroCAD.  You may view their letter of acceptance and list of accepted software in PDF format.  Other agencies that have accepted/approved/endorsed HydroCAD include Delaware DNREC, and Plymouth, MN.

Most agencies take the alternate approach of considering each application on its merits, rather than performing a separate evaluation of the software.  To our knowledge, there have been no cases where an agency that accepts that underlying methodology has refused an application simply because it was prepared with HydroCAD.

As a general rule, project acceptance or rejection is dependent on the work of the submitting engineer, rather than on the choice of software tools.  However, many customers have reported that the clarity of the HydroCAD reports have been a great aid in the acceptance of their proposals.

For further information on who uses HydroCAD, we have prepared a representative customer list and links to select customer web sites.

FEMA Acceptance

The Federal Emergency Management Agency (FEMA), accepts only calculations that are performed with programs it has specifically reviewed and accepted, such as TR-20, HEC-1 and HEC-2.  Although HydroCAD employs most of the same techniques as the accepted TR-20 model, and produces comparable results, FEMA requires a separate review of any program that does not use the actual code of an accepted model.

Unfortunately, current FEMA policy (as of August 2004) is that FEMA is no longer conducting reviews of any commercial software product.  Although we will continue to work with FEMA and other agencies to gain formal acceptance, the new policies appear to prevent the acceptance of "new" programs, regardless of merit.

Although we do have many customers who have used HydroCAD in projects requiring FEMA approval, the use of HydroCAD has been limited to portions of the project where "non-approved" techniques were permitted.

Another option has been to employ HydroCAD for general modeling of a project, and then utilize an "approved" model (such as HEC-2) for the preparation of the actual submission. Despite the duplicate calculations, this approach can still be less time-consuming than having to do the entire project without the time-saving benefits of HydroCAD.


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