SWMM does provide the ability to model specific LIDs, but it depends on what kinds of LIDs you want to model. In my experience, SWMM hydrology is often the biggest hurdle to obtaining client buy off for standard SWMM, but it doesn't have to be a hurdle. Will they require you use one method vs the other? How much additional work will it be to change the hydrologic approach? Is the change worth the hassle? I would recommend that you have a thorough understanding of both approaches so you can advocate for your clients' best interest here. PCSWMM does now provide the ability to model unit hydrograph methods like the SCS method, but they are not provided within the SWMM engine itself.

SWMM uses a Kinematic Wave method for basin runoff that is not as well known by most local US agencies. I'm also interested in hearing about any studies where both models have been used, and how they might compare, particularly with respect to peak flow estimations.ДЇor your discussion with the client about the use of SWMM vs HydroCAD, I would separate out the comparison between hydrology and hydraulics.ДЇor the hydrology discussion, the HydroCAD model would likely use the SCS CN loss method with unit hydrographs. SWMM includes the dynamic wave routing method and can more accurately simulate conduit storage, backwater, flow reversal, and pressurized flow SWMM offers more flexibility in simulating infiltration, etc.), I'm curious to see if others have opinions regarding the use of SWMM vs. However, questions are being raised as to why we are not sticking with HydroCAD, and what makes SWMM the more 'appropriate' model over HydroCAD for this application.Д«esides the obvious answers (i.e.

Previous work by others included the use of HydroCAD to simulate flows, but I've created an updated model using PCSWMM, thinking SWMM is much better suited to model flood flows through the existing drainage network. The plan is to identify potential GSI retrofits throughout the basin, with the goal of reducing peak flows discharging to a degrading channel. I'm currently working on a project that involves a storm drainage network with open swales leading to closed conduit piping, in a semi-urban setting.

Pcswmm vs epa swmm