Sewer areas

Arcadis2 27

Dear Tygron support,

I am trying to properly model the sewer system in my area. I selected the multiple option in sewer areas, to use all sewer areas available. I know the storage in the sewer system is 21.6 mm and manually changed this for all sewer areas to ensure the sewers would portray an accurate storage capacity, and double checked if the total sewer storage capacity presented in Tygron is correct. To check if the model worked sufficiently, I simulated a rainfall of 20 mm/hour in the rainfall overlay. As such storm leads to less water in the area than the volume that can be stored in the sewers (considering the sewer storage capacity reported by Tygron), there should be almost no water on the streets (regardless of some small puddles) as the storage capacity of the sewers is greater than the total amount of rainfall. However, there still occur a lot of puddles over 10 cm deep. Could you explain why this happens and how I can fix this problem?

Keen to hear from you!

Kind regards,

Laura

RudolfNL

Hi Laura,

You can find more details about how the sewer model operates here:

https://support.tygron.com/wiki/Sewer_model_(Water_Overlay)

There are 2 important things to take into account:

The sewer storage capacity is computed only for the overlap between sewered constructions and sewer areas. Unless your entire sewer area is entirely covered by constructions which are connected to the sewer, the average storage capacity for the sewer area will compute to be lower than 21.6mm. Rather than, for example 100m² x 21.6mm = 2.16m³, it may be that only 50m² is connected to the sewer, resulting in 50m² x 21.6mm = 1.08m³ of water storage.

The sewer will only allow water to flow in in the locations where a construction is connected to the sewer. If your water collects in a location where no sewered construction exists, it will not have access to the sewer and can ony flow away through other means, such as surface flow or evaporation.

Regards!