Quantification of uncertainties have been implemented regarding stormwater flows and required flow detention volume and pollution transport (concentration and quantity) of various pollutants from existing and planned areas before and after different types of treatment and detention measures.

There is a large demand to get further knowledge about the uncertainties in different parameters of indata and of the modelled results. This quantification of uncertainty would provide an improvement and extension of the tool and be of benefit to the action work in accordance with the Water Directive.

Each part where there are inputs and outputs of uncertainties is based on data from literature studies and selected methods are generally scientifically accepted.
The uncertainties are specified as input fields in the form of relative percent uncertainties (recommended default and interval values that can be changed by the user).

Results are presented in the results report R as absolute uncertainties (+/-) for the following parameters:
– stormwater flow (l/s)
– base flow (l/s)
– groundwater and base flow concentration (µg/l)
– total content before and after treatment (µg/l)
– total load before and after treatment (kg/year)
– design flow (l/s)
– required detention volume (m3)

There will be continuous further development around this quantification of uncertainty in the form of scientific papers in collaboration with Luleå University of Technology.