Problem

How can I model evaporation from a pond in SewerGEMS and CIvilStorm?

Solution

With PondPack or the Implicit dynamic solver in SewerGEMS or CivilStorm, this can be done by using one of the available infiltration methods in the pond properties.

With the Explicit dynamic (SWMM) solver in SewerGEMS or CivilStorm, the climatology options can be used to account for evaporation. First, you have to specify the evaporation loss under SWMM Extension, which is found by going to Components > Other > SWMM Extensions > Climatology. Next, go to the Evaporation tab. There, select the Evaporation Type from the pulldown menu.

Next, go to the Pond properties and specify the actual evaporation / potential evaporation. If you want to test the system with the full effect of evaporation choose this factor as 1. If only a part of the potential evaporation is accounted for in the evaporation loss specify the factor based on the percentage; i.e. if 50% then 0.5.

When you run the analysis using the EPA-SWMM runoff method (where this evaporation factor is supported) check the Calculation Summary under the "Storage" tab. You will see the percentage of evaporation compared to the total volume. This can give you an idea of the evaporation loss from the pond.

In CivilStorm or SewerGEMS, go to Help > Loading > Pond Flow Loss and review the material there for reference.

See Also

Using the Average Infiltration (Seepage) method for ponds

How Infiltration is calculated when using the "Infiltration Head / Depth" method

How to model aquifers in SewerGEMS and CivilStorm using the SWMM solver