Quantification of uncertainties for stormwater calculations of pollution, reduction, flow and detention

Purpose and goal

The purpose is to develop a methodology for quantifying uncertainty in calculations regarding flows, flow detention and pollutions in stormwater and base flow, and for use in the Water Directive´s action work. The goal is also to implement the methodology in the StormTac Web model for national and international spreading. The goal has been met by establishing a document as a basis for scientific articles and by implementing the method in StormTac Web. The method thus comes into direct use in projects, research and education.

Expected results and effects

The project has resulted in identification of the most appropriate methods for quantifying uncertainties for stormwater calculations and in values of estimated uncertainties for the most significant input data. The uncertainties for the estimated results have also been calculated by accepted methodology. The implementation in StormTac Web is complete and available. Methodology and results are documented as a draft for planned articles. Individuals who will participate in continued article writing have been determined, as well as continued contacts have been identified.

Planned approach and implementation

A methodology has been developed through literature studies for quantifying the uncertainty in input data (runoff coefficients, precipitation, size of catchment area and concentrations) and calculation results (total concentrations and amounts of pollutants in the discharges to the recipient before and after treatment as well as flows and required flow detention). The methodology has been implemented in the stormwater and recipient model StormTac Web. The most important methods have been identified, as well as what input and output are included. Continued work has been planned.