Green infrastructure (GI) has been identified as a cost-effective, environmentally friendly, and socially pleasingsolution to stormwater management issues in these shrinkingcities. As an example, bioswales are added to existingimpervious surfaces where rainwater is directed into smallvegetated basins in an effort to capture it for floodprevention and other ecosystem services. However, oncethese retrofits are made, they are left to their own devices;little is known about how the ecohydrology might influencethe function of these bioswales and their potential forstormwater management and ecosystem services.

1. Rationale

8. Acknowledgments

Emily Seifert1*, Steven J. Kopeck1,2*, Kyotaek Hwang,1 and Shirley A. Papuga1* (shirley.papuga@wayne.edu)1Dept of Geology, WSU,2Dept of Civil & Environmental Engineering, WSU, *undergraduate student

Ecohydrology of Green Infrastructure Retrofitting for Stormwater Management: A Case Study in Detroit, MI

Stormwater management is an increasingly pressing andcomplex urban problem. This is especially true for shrinkingcities with aging and outdated gray stormwaterinfrastructure, where economies may not be able to supportcostly upgrades. That infrastructure often includes acombined sewer system that collects and treats rainwaterrunoff, domestic sewage, and industrial waste-water alltogether. During heavy rain events these systems can getoverloaded and dump sewage into the local waterways,leading to a multitude of environmental consequences.

We are grateful to Richard Barber and his Interdisciplinary Research Programfor enabling this research. This research is also supported by NSF CNHaward 1518376 and NSF SRN award 1444758. We also note help frommultiple field assistants including Alex Eklund, Natalie Lyon, Adam Pruett,Isidore Harris, Orlando Rios, Oluwafemi Aregbesola. Kennadi Rankin,Connor Socarates, Elana Chan, and Amy Leslie..

7. Take Home Points

https://clu-in.org/issues/default.focus/sec/vapor_intrusion/cat/site_investigation_tools/

3. Ecohydrological Quandary

4. Instrumentation and Sampling

Unlike arid regions where high WUE isdesirable, we hypothesize that in thisregion, the most successful GI willneed to include plants with high wateruse per carbon uptake (low WUE).

5. Time Series (7 day)

Installed 2017 Planted 2018 Total area 43,737 ft2

Impervious 40,425 ft2

Bioswale 3,313 ft2

Drains to underground network of pipes.

WSU Bioswale Parking Lot Retrofit

Federal and State regulations require Detroit Water and Sewerage Department (DWSD) toinvest over $1 billion to help prevent untreated overflows into the Detroit and Rouge rivers.

Water Use Efficiency (WUE): Ratioof plant biomass produced to water lostvia transpiration

In Detroit, we need to getrid of a lot of water, fast.

2. Bioswale Water BudgetInputs: Precipitation Inflow from lot

Outputs: Evapotranspiration Outflow from pipes

Storage: Soil Moisture

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Some of our native plants.

Beginning in Spring 2018: 2 phenocams (greenness) 10 I-buttons at 10 cm (temp/humidity) weekly soil moisture measurements new rooftop campus weather station

Beginning Summer 2018: pressure transducers (inflow/outflow) leaf porometers (plant water use)

North Drain TransducerNorth Inlet Transducer

Region of Interest

Pixels don’t become more green, but instead became less blue & red, i.e. (Richardson et al. 2007):

Greenness = (G – R) + (G – B)

Real time data and pics from our weather station

@weatheratwayne

6. Regressions (7 day)

2018

Air temperature in center is less responsive than air temperature at either end

Rain occurs all year, with some wetter (late Sept; early Oct) and some drier (mid July) periods

Soil moisture higher at ends than in the center

Greenness reveals a typical growing season with plants at north end possibly more sensitive to rainfall

Species differ in their stomatal response to moisture

Stomatal conductance appears to generally increase and decrease in parallel with greenness

Air temp seems to be a stronger driver for greenness than soil moisture WUE is species-specific, with none having high WUE; Lanceleaf has

low WUE; the other two falling to the right in our conceptual figure

Plant species matter in designing bioswales; in wetter environments plants without ahigh WUE may be more appropriate for success

Bioswales can handle both small and large storms; however as an increase in largerstorms threatens our region, our GI may need to be adapted to handle the additionalstormwater inputs

2019