New publication on the impact of the runoff coefficient on rain duration and intensity

In the latest issue of “Tidskriften VATTEN”, Thomas Larm and Anna Wahlsten from StormTac have together with Tyréns and Luleå tehnical University written the publication: “Effects of green areas and design rains on runoff coefficients for design of stormwater facilities”.

The publication contains information and recommendations regarding how to calculate adapted runoff coefficients for calculated design flows and required detention volume, which are not static according to tables in P110 but are adapted according to the following factors:

– Design rain duration, which affects the degree of soil saturation and the infiltration, and thus the runoff coefficient to be used in the calculations.
– Design rain intensity for design rain duration, where higher intensity gives a higher runoff coefficient.

Proposed functions and reported diagrams can be used to obtain a more adapted runoff coefficient for your calculations, which can be manually entered as new input data in the model until further notice, but which we will implement in the model as an option.

The publication also shows how various factors, such as climate factors and the effect of green areas, affect the dsign flow and the required detention volume. This can provide increased understanding of how sensitive different factors are in the calculations so you know which are the most important to investigate more closely and how much they can affect the results.

Read more in the latest publication of “Tidskriften Vatten nr 4 2023” Link: https://lnkd.in/d5wt8zFv