You can model the pond infiltration indirectly by using either:
1. a Pump Type 4 (the classic SWMM 4 solution to this matter), in which the Pump simulates the pond depth - infiltration rate function,
2. alter the SWMM 5 Evap Factor for a pond so that you have seasonal or monthly variation in your infiltration loss simulated as an increase in Pan Evaporation or
3. You can use the newer SWMM 5 Outlet structure and use either a functional or tabular relationship to simulate the infiltration loss as a function of pond depth.
If you search the CHI Knowledge database you can also find some suggestions from Mike Gregory (and others) about modeling infiltration loss from a pond. I would recommend items 2 and 3 because "An outlet curve in SWMM 5 has the same functionality as a SWMM 4 Depth related pump ( Flow versus Depth) but it has the great advantage of being explicitly designed to have multiple functions; does not have the appearance of being an ad hoc solution (as a pump simulating infiltration would be to the casual viewer) and has many wonderful other features (added by Lewis Rossman) that you would not get with a strict pump link."
Here's the expanded version with emojis:
### SWMM 5 Pond Infiltration 🌊💧
You can model the pond infiltration indirectly by using either: 🤔
1\. a Pump Type 4 (the classic SWMM 4 solution to this matter), in which the Pump simulates the pond depth - infiltration rate function, 🆚
2\. alter the SWMM 5 Evap Factor for a pond so that you have seasonal or monthly variation in your infiltration loss simulated as an increase in Pan Evaporation 🌞 or
3\. You can use the newer SWMM 5 Outlet structure and use either a functional or tabular relationship to simulate the infiltration loss as a function of pond depth. 🔬
If you search the CHI Knowledge database 🔍 you can also find some suggestions from Mike Gregory (and others) about modeling infiltration loss from a pond. I would recommend items 2 and 3 because "An outlet curve in SWMM 5 has the same functionality as a SWMM 4 Depth related pump ( Flow versus Depth) but it has the great advantage of being explicitly designed to have multiple functions; does not have the appearance of being an ad hoc solution (as a pump simulating infiltration would be to the casual viewer) and has many wonderful other features (added by Lewis Rossman) that you would not get with a strict pump link." 👌
