SuDS performance evaluation tool (StopUP)

The SuDS performance evaluation tool was built by HR Wallingford as part of the EC StopUP project. The tool is a simple volume balancing tool. The SuDS are represented as simple storage reservoirs which use up to three storage layers (‘drainage’, ‘soil’ and ‘surface’) and transfer water between the layers using simple rules. Unlike more complex drainage software, the routing through the SuDS and connecting pipework are not fully represented, but it does include a simplified approach to reflect the hydraulic influence of downstream SuDS. The water quality model is not physically based but uses a pollutant wash-off model combined with average event mean concentrations reflective of different land use types. The efficiency of SuDS to remove pollutants reflects observed removal rates for typical components (based on measured influent and effluent concentrations published in summaries of data held within the BMP database. 

SuDS best practice is to manage rainwater on or close to the surface and as close to the source of the runoff as possible, as well as to treat rainwater as a valuable resource and ensure pollution is managed at source. This tool provides a thorough evaluation of a SuDS scheme against these best practice principles, notably whether the SuDS scheme meets interception criteria, where surface water goes throughout the year and by how much pollution might be reduced by the system. The tool is useful throughout the design stage to facilitate good SuDS design.

The surface water storage volume design tool is a simple online tool. The tool is currently hosted on the EC StopUP website (where it is labelled the “StopUP SuDS Tool”) and therefore users will need to register separately. 

To use the tool, you will need to follow these steps:

1. Build your scheme by defining each of your SuDS components (over a background map/image if you prefer)
2. Link your SuDS components together into a network
3. Add contributing urban areas
4. Define a suitable outfall
5. Select or input the rainfall you would like to use
6. Edit the runoff, evapotranspiration and pollutant values if you wish
7. Define any site information you would like to be displayed on the PDF reports
8. Run the model
9. Explore the results!

The SuDS performance evaluation tool can evaluate the system for both extreme events and everyday rainfall. The tool provides an evaluation of the system in terms of peak flow rate and flooding from the drainage system for design storms, and an evaluation of the system in terms of interception, where surface water goes throughout the year (reuse, evapotranspiration, infiltration, outfall) and by how much pollution might be reduced by the system for time series rainfall. 

A report of all input data and results can be saved to form part of a drainage strategy or planning application. The tool also provides an evaluation of the system design for the following criteria: runoff destination, interception, flow control, water quality, amenity and biodiversity.