One of the aspects we love about UDM events is the deep discussion fostered by inspirational topics. We’ve set aside time in the conference program for you to join in these discussions during 1-hr Special Sessions and Workshops. Look for these topics in the conference program: 

  • Performance Metrics for Green Stormwater Infrastructure 
  • Community-driven Open-source SWMM, Where Next? 

Scroll through this page for a description of each session. 

Workshop: Performance Metrics for Green Stormwater Infrastructure

Convenor: Prof. Virginia Stovin, University of Sheffield 

In most jurisdictions, conventional stormwater infrastructure for runoff quantity control (i.e. underground pipes and tanks) is designed based on idealized high return period design storms.  Often the system is assumed to be ‘empty’ prior to the start of rainfall. There are several reasons why this approach may be inappropriate for the design and approval of SuDS/LIDs: 

  • SuDS/LID devices are typically reliant on natural hydrological processes (infiltration and/or evapotranspiration) to restore their retention capacity.  These may occur more slowly compared with drain-down times associated with conventional drainage systems, such that the SuDS/LID will not always be at full retention capacity when the next storm occurs. Depending on assumption made (0-100% capacity available), the system will be over-or under-designed respectively. 
  • A focus on high return period events may rule out SuDS/LID options unable to achieve such stringent requirements, whilst ignoring multiple other hydromorphological and water quality benefits that could be achieved through the effective management of routine events.  

The aim of this workshop is to consider alternative approaches to setting performance targets.  It is expected that suitable metrics would be derived from simulated responses to long duration (10 yr+) high temporal resolution (5 min) continuous rainfall inputs.  What are the right metrics to use in a drainage design/regulatory context? These could include probabilistic performance targets based on flow duration curves, or multiple metrics aimed at characterizing runoff volumes and runoff rates for events with lower return periods (e.g. annual) (Stovin et al., 2017; Quinn et al.,2021).  We expect the discussion to focus mainly on stormwater runoff quantity, but implications for water quality and other (multiple) benefits should be noted. While continuous simulation is feasible at the device/development scale, its computational expense prevents such approaches being applied at the city/catchment scale.  Simplified/surrogate modelling techniques are potentially useful in this context.  

The format of the workshop will be a brief introductory presentation followed by an open discussion. It is anticipated that the workshop discussions will lead to a position paper being submitted to a relevant academic journal. 

Workshop: Community-driven Open-source SWMM, Where Next? 

Convenor: Prof. Ben Hodges, University of Texas at Austin 

This workshop aims to gain insight into the community perceptions on the future development of open-source SWMM. Although EPA-SWMM is formally maintained and distributed by the US EPA, it is (and always has been) a public-domain open-source model. The new development of SWMM5+ and the establishment of the Center for Infrastructure Modelling and Management (CIMM) as a US-based 501c(3) non-profit (charitable) organization has the potential to jump-start community involvement in improving the SWMM code. This objective of this workshop is to establish whether or not the community is interested in participating in open-source code development for SWMM.  The end product of the workshop will be a short paper that provides a discussion of community perceptions, consensus, and disagreements.  

Of particular interest are opinions on:  

  1. What new capabilities are needed in SWMM?  
  2. What people/organizations are interested in making open-source contributions?  
  3. What are some of the funding sources that the community might look to?  
  4. What are recommended “best practices” for integrating the community product with EPA?   

The workshop is looking to document diverse opinions rather than establish a consensus on such complex topics. The work product of the workshop will be a short paper. The draft paper prepared by the convenors and reported out at the close of the conference to all participants. The convenors will circulate the draft for comments among all conference participants and prepare a final version incorporating feedback within 30 days of the conference completion.