Performance and Effectiveness of Urban Green Infrastructure: Maximizing Benefits at the Subwatershed Scale through Measurement, Modeling, and Community-Based Implementation

PIs: Arthur E. McGarity (Lead PI, Swarthmore College), Megan Heckert (Westchester University), Benjamin Hobbs (The Johns Hopkins Univrsity), Christina Rosan (Temple University), and Claire Welty (UMBC)

Funding Source: US EPA STAR Program (9/1/13 - 8/31/17)

SUMMARY

Objectives
The objectives of this project are to:
(1) Evaluate selected Green Infrastructure (GI) demonstration projects in the Philadelphia Combined Sewer Overflow (CSO) area to measure and model technical performance;
(2) Develop a methodology for creating zones of green infrastructure (ZGIs) that encompass attributes influencing performance, benefits, and costs of GI practices, in the context of community-based adaptive implementation;
(3) Develop quantitative GI benefit-investment functions for each zone for maximization of benefits and minimization of costs through evaluation of multiple benefits;
(4) Incorporate benefit functions into tools for evaluation, optimization, and adaptive implementation of GI practices to facilitate transfer of this project’s results to other urban centers; and
(5) Incorporate STEM learning at multiple levels in all phases of the project.

Experimental Approach
The experimental approach includes the following components:
(1) Select three sites where high-performing next-generation GI practices will be installed in the CSO area to evaluate individual GI practice performance and combined effectiveness at the subwatershed level and calibrate a subsurface flow model to observational data;
(2) Conduct interactive community-based research engaging our community and municipal partners who will bring local experience with the Philadelphia Water Department’s Green City, Clean Waters program related to the effectiveness of GI investments;
(3) Use simulation models, evolutionary optimization, and spatial statistics to develop mathematical benefit functions that estimate GI costs and predict benefits (e.g., runoff reductions, improvements in ecosystem services, and ancillary community benefits); and
(4) Quantify uncertainties in benefit functions and include them in an adaptive management process incorporating multiple objectives by extending the StormWISE framework for systematic evaluation of trade-offs among different benefits.

Expected Results
Outputs will be refined methodologies for accurate life-cycle performance assessment of GI practices and for evaluation of cost-effective, adaptive GI implementation strategies at the subwatershed scale. Project outcomes are expected to increase national capabilities for assessing and implementing cost-effective GI practices for urban stormwater management at the subwatershed level, especially in cities with combined sewers.