For a week in October 2016, I had over 38,000 twitter followers as I took a turn hosting the @realscientists account. Of course, I spent a bunch of my time preaching the gospel of stormwater management. Here are tweets over two days synopsizing its history in 140 character bites. (Please note that the account is hosted by a different scientist each week. The image attached to these tweets is that of the current @realscientists host, not a crazy makeover of Anne.)
A major focus for the Watershed Hydrology lab this fall has been preparing for the Kent State University Water and Land Symposium. Anne Jefferson was the symposium co-chair (with lots of help from Biology’s Chris Blackwood), and all of the lab members were involved in some way. Pedro, Laura, Hayley, and Cody presented posters. Caytie and Garrett helped with set up and were on tweeting duty. The symposium had about 400 attendees from universities, agencies, cities, non-profits, and the general public from throughout northeast Ohio. If you missed the event live or on twitter, here’s how it went down.
This year’s symposium occurred on October 5-6, 2016, and featured the theme of “Sustainability and Resilience on the Land-Water Continuum.”
Today in my flvuial processes class, we’re going to discuss a great paper by Gran et al. on “Landscape evolution, valley excavation, and terrace development following abrupt postglacial baselevel fall.” The paper is set in a landscape I know well – southern Minnesota’s Minnesota River Basin. For my students in northeastern Ohio, this landscape would feel somewhat similar to the area around here, but not quite. Similarly, the glacial history has some degree of overlap (glaciers covering the region and retreating about ~14,000 years ago), but there are some unique elements of each place. Fortunately, I found a series of short video clips that do a nice job of setting the Minnesota River story in its context.
The tributaries to the Minnesota River are still relaxing after all of this geologic excitement. As a result, many of the tributaries exhibit knickpoints or knick zones – steepened areas on the channel profile.
You don’t have to go to the primary literature to learn about the knickpoints and what’s going on in the Minnesota tributaries, thanks to a nice short discussion by Karen Gran. There’s even a huge knickpoint left on the Mississippi River in Minneapolis as a result of the Glacial River Warren and draining of Lake Agassiz. You can read about that one here.
For a great discussion of fixed versus mobile knickpoints, check out this essay by Ben Crosby, who did his PhD work on a particularly knickpoint rich landscape in New Zealand. More good discussion of knickpoint mobility can be found in this blog post by Chuck Bailey. Finally, Steven Schimmrich has a nice series of blog posts on knickpoint retreat at Niagara Falls.
If that’s not enough, knickpoint retreat is often associated with the formation of terraces. There are two types of terraces to come to terms with. Cut-and-fill terraces, where the unconsolidated sediments are actually alluvium, show that the river has had periods of both aggradation and incision (and lateral planation of the valley bottom). In rivers with strath terraces, aggradational periods are either relatively minor or non-existent and the terraces represent alternating periods of incision and lateral planation. Callan Bentley has illustrated each type of terrace below, and you should see his post and comments for good discussion of the intricacies of naming and describing these features.
Congratulations to long-time collaborator and newly minted Ph.D., Dr. Colin D. Bell. Colin has been working on monitoring and modeling the downstream effects of stormwater ponds and wetlands in Charlotte, NC since he started graduate school there in 2011. Five years later, he’s defended his Ph.D. on June 30, 2016 at Purdue University under the mentorship of Dr. Sara McMillan. Colin’s PhD dissertation title was “INFLUENCE OF STORMWATER CONTROL MEASURES ON WATERSHED HYDROLOGY AND BIOGEOCHEMICAL CYCLING.”
Colin was a key contributor to a 2015 paper on using isotope hydrograph separation to understand the contribution of stormwater ponds to urban headwater streamflow. He’s currently got two first author papers in review and much more still left to turn from dissertation to manuscript, so we’ll be seeing more good things coming out of his PhD work for the next several years.
Colin’s next stop is a postdoc with Dr. Terri Hogue at the Colorado School of Mines.
I was asked to submit an abstract for the Water Management Association of Ohio conference in November. I’m going to try to sum up 4 years worth of work on the green infrastructure retrofit we’ve been studying in Parma, and I’m looking forward to learning about from the other presenters at this very applied conference.
A Neighborhood-Scale Green Infrastructure Retrofit: Experimental Results, Model Simulations, and Resident Perspectives
Anne J. Jefferson, Pedro M. Avellaneda, Kimberly M. Jarden, V. Kelly Turner, Jennifer M. Grieser
There is growing interest in distributed green infrastructure approaches to stormwater management that can be retrofit into existing development, but there are relatively few studies that demonstrate effectiveness of these approaches at the neighborhood scale. In suburban northeastern Ohio, homeowners on a residential street with 55% impervious surface were given the opportunity to receive free rain barrels, rain gardens, and bioretention cells. Of 163 parcels, only 22 owners (13.5%) chose to participate, despite intense outreach efforts. After pre-treatment monitoring, 37 rain barrels, 7 rain gardens, and 16 street-side bioretention cells were installed in 2013-2014. The monitoring results indicate that the green infrastructure succeeded in reducing peak flows by up to 33% and total runoff volume by up to 40% per storm. The lag time between precipitation and stormflow also increased. A calibrated and validated SWMM model was built to explore the long-term effectiveness of the green infrastructure under 20 years of historical precipitation data. Model results confirm that green infrastructure reduced surface runoff and increased infiltration and evaporation. The model shows that the green infrastructure is capable of reducing flows by >40% at the 1, 2, and 5 year return period, and that, in this project, more benefit is derived from the street-side bioretention cells than from the rain barrels and gardens that treat rooftop runoff. Surveys indicate that many residents viewed stormwater as the city’s problem and had negative perceptions of green infrastructure, despite slightly pro-environment values generally. Substantial hydrological gains were achieved despite low homeowner participation. The project showcases the value of careful experimental design and monitoring to quantify the effects of a green infrastructure project. Finally, the calibrated model allows us to explore a wider range of hydrologic dynamics than can be captured by a monitoring program.
Graduate student Laura Sugano will be representing the Watershed Hydrology lab at this year’s Geological Society of America conference in September. Even though this summer has been very dry, Laura has lots of great data to share with conference goers.
Update: Laura will be giving a talk in the Urban Geochemistry session on Wednesday afternoon.
Evaluating Bioretention Cell and Green Roof Performance in Northeastern Ohio
Laura L. Sugano*, Anne J. Jefferson, Lauren E. Kinsman-Costello, Pedro Avellaneda
Kent State University
In urban areas, increased runoff from storm events causes flooding, erosion, ecosystem disturbance, and water quality problems. Green stormwater infrastructure is designed to ameliorate these effects by decreasing the flow rate, overall volume of runoff, and nutrient loads. We compared the effectiveness of a co-located green roof and bioretention cell in order to understand their relative capacities to decrease stormwater runoff and nitrate (NO3-) loads, when subjected to the same weather conditions. Our field site was the Cleveland Metroparks’ Watershed Stewardship Center in Parma, Ohio. Beginning in June 2015, we monitored inflows to and outflows from a bioretention cell draining a paved parking lot and a vegetated roof during 84 storms. Discharge, level, and velocity were measured using an area/-velocity meter at the outflow structure of each site. To assess water quality in water samples, we measured NO3- concentrations using ion chromatography. Event sizes spanned from 0.25 mm to 54 mm. The bioretention cell completely retained flow from 75% of the storm events, and the green roof retained 49% of storms. The bioretention cell completely retained all events smaller than 3.05 mm and the green roof completely retained all events smaller than 0.51 mm. The bioretention cell completely retained 64% of the storm events in summer 2015, 90% in fall 2015, and 77% in winter 2015-2016. The green roof completely retained 37% of the storm events in summer 2015, 48% in fall 2015, and 89% in winter 2015-2016. The groundwater level in the bioretention cell increases in response to storm events and lowers between storms. The soil moisture in the green roof increases during storm events and slowly decreases between storms. NO3- concentration differences between inflows and outflow suggest that more NO3- is removed from inflow to outflow in the bioretention cell than in the green roof. Our study suggests that bioretention cells can decrease stormwater flow and volume and can improve NO3- concentrations better than green roofs because they have the capacity to retain more stormwater and NO3-, due to their thicker substrate and their ground-location, which allows them to retain runoff as well as direct precipitation.
Watershed Hydrology lab undergraduate Cody Unferdorfer will be representing the lab at this year’s Geological Society of America meeting in Denver in September. The work that he will be presenting will build on preliminary work that won the Kent State University Undergraduate Research Symposium Geology/Geography division in April, and Cody will have more and better data and analyses to show of at GSA.
Update: Cody will be giving a poster in the session on Undergraduate Research Projects in Hydrogeology on Sunday.
Surface runoff from a closed landfill and the effects on wetland suspended sediment and water quality
Cody Unferdorfer (1), Anne Jefferson (1), Lauren Kinsman-Costello (2), Hayley Buzulencia (1), Laura Sugano (1)
1. Department of Geology, Kent State University
2. Department of Biological Sciences, Kent State University
During rainstorms, many wetlands receive surface runoff carrying sediment and dissolved materials. Some of the sediment and solutes remain within the wetland, where they impact aquatic organisms and nutrient cycling. With time, excess sediment can fill in a water body and destroy the aquatic ecosystem, or excess nutrients can lead to eutrophication. Closed landfills have compacted surfaces that can generate large amounts of surface runoff, and the goal of this project is to examine the effects of a closed landfill’s runoff on a wetland.
The study site is a constructed wetland in Parma, Ohio. Water samples were collected during storms beginning in July 2015. We monitored five locations at the wetland: inflow from the landfill; inflow from two green infrastructure treatment trains; inflow from a stream seep, and outflow. Water samples were analyzed for suspended sediment concentration, water stable isotopes, and dissolved forms of nitrogen and phosphorus. Discharge was measured at the outflow.
Based on a preliminary analysis of four storms, of the inflows; the landfill contributes the most suspended sediment with an average of 400 mg/L. There is no correlation between TSS and discharge at the outflow. Instead a first flush effect was observed, where TSS concentrations decreased with time. The landfill inflow is close to the wetland outflow, which could allow for suspended sediment to bypass most interaction with the wetland’s interior. However, comparing rain and wetland outflow stable isotopes shows that water residence time often exceeds a single storm, suggesting that there are opportunities for biogeochemical processing of nutrient inputs within the wetland.
Back in mid-April, I was invited to do an AGU-facilitated Ask Me Anything on r/AskScienceDiscussion/ along with Dr. Kim Cobb. Here’s how we introduced ourselves:
AGU AMA: I’m Dr. Kim Cobb, and I’m here to talk about the science of climate change, El Niño, and the reconstruction of past climate. And I’m Dr. Anne Jefferson, and I’m here to talk about how water moves through landscapes and how land use and climate change alter hydrology. Ask Us Anything!
We got fantastic questions and did our best to answer what we could. I encourage you to dip into the questions and answers and see for yourself.
Graduate student Laura Sugano will also be presenting her green infrastructure research at the CUAHSI Biennial Symposium in July.
Evaluating Bioretention Cell and Green Roof Hydrologic Performance in northeastern Ohio
Laura L. Sugano*, Anne J. Jefferson, Lauren E. Kinsman-Costello, Pedro Avellaneda
Kent State University
In urban areas, increased runoff from storm events is a significant concern due to flooding, erosion, ecosystem disturbance, and water quality problems. Green stormwater infrastructure is designed to ameliorate these effects by decreasing the flow rate and overall volume of runoff. We compared the effectiveness of a co-located green roof and bioretention cell in order to understand their relative capacities to decrease stormwater runoff, when subjected to the same weather conditions. Our field site was the Cleveland Metroparks’ Watershed Stewardship Center in Parma, Ohio. Beginning in June 2015, rainfall, underdrained outflow, groundwater levels, and soil moisture have been measured on 1-5 minute intervals during 84 storms. Event sizes spanned from 0.25 mm to 54 mm. The bioretention cell completely retained flow from 75% of the storm events, and the green roof retained 49% of storms. The bioretention cell completely retained all events smaller than 3.05 mm and the green roof completely retained all events smaller than 0.51 mm, though some larger events were also completely retained. For storms where underdrain outflow occurred, the average retention was 25% for the bioretention cell and 79% for the green roof. The bioretention cell completely retained 64% of the storm events in summer 2015, 90% in fall 2015, and 77% in winter 2015-2016. The green roof completely retained 37% of the storm events in summer 2015, 48% in fall 2015, and 89% in winter 2015-2016. The groundwater level in the bioretention cell increases in response to storm events and lowers between storms. The soil moisture in the green roof increases during storm events and slowly decreases between storms. My study suggests that bioretention cells can mitigate stormwater issues better than green roofs because they have the capacity to retain more stormwater due to their thicker substrate and their ground-location allows it to retain surface runoff as well as direct precipitation.
The Watershed Hydrology Lab will be represented at the CUAHSI Biennial Symposium in July in West Virginia. Pedro Avellaneda and Laura Sugano have been awarded travel grants to present their research. Here’s Pedro’s abstract:
Long-term simulation of green infrastructure effects at a catchment-scale
Pedro M. Avellaneda1, Anne J. Jefferson2, Jennifer M. Grieser3
1 Department of Geology, Kent State University, 221 McGilvery Hall, Kent, OH, 44242, USA; Phone: 330-672-2680; email: email@example.com
2 Department of Geology, Kent State University, 221 McGilvery Hall, Kent, OH, 44242, USA; Phone: 330-672-2746; email: firstname.lastname@example.org
3 Cleveland Metroparks, 2277 W Ridgewood Dr, Parma, OH, 44134, USA; Phone: 440-253-2163; email: email@example.com
In this study, we evaluated the cumulative hydrologic performance of green infrastructure in a residential area of the city of Parma, Ohio, draining to a tributary of the Cuyahoga River. Green infrastructure involved the following spatially distributed devices: 16 street side bioretentions, 7 rain gardens, and 37 rain barrels. The catchment has an area of 7.2 ha, in which 0.7% is occupied by green infrastructure and 40% is covered by impervious surfaces. Green infrastructure is expected to treat 72% of impervious areas. The engineered soils for the bioretentions and rain gardens consisted of sand (~72%), organic matter (5-28%), and clay (~10%). Data consisted of rainfall and outfall flow records for a wide range of storm events ?from 0.3 mm to 81.3 mm of measurable precipitation? including pre-treatment and treatment periods. The rainfall-runoff process was simulated for a 10 year period using the Stormwater Management Model (SWMM), a dynamic hydrology and hydraulic model that incorporates green infrastructure. Two scenarios were considered for the application of the SWMM model: pre-treatment, considering observed data before construction of green infrastructure; and treatment, considering observed data after installation of green infrastructure. The calibrated and validated SWMM model was used to evaluate ?using the same climate characteristics? the long-term hydrologic alteration due to the green infrastructure. A 0.8% increase in evaporation, a 12% increase in infiltration, a 1.6% drainage from green infrastructure, and a 14.4% reduction in surface runoff were produced. A simulated flow duration curve for the treatment scenario was compared to that of a pre-treatment scenario. The flow duration curve shifted downwards for the green infrastructure scenario, with a 30% decrease in the Q99, Q98, and Q95 percentiles. Parameter and predictive uncertainties were inspected by implementing a Bayesian statistical approach.