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urban hydrology

What is stormwater? And how did we get to where we are today?

realscientistsFor 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.)

Water Management Association of Ohio conference abstract: A Neighborhood-Scale Green Infrastructure Retrofit

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.

Hydrologic response to watershed metrics describing urban development and mitigation with stormwater control measures

Watershed Hydrology lab collaborator and Ph.D. candidate Colin Bell will be giving a talk in T106. From Green Roofs and Gutters to Urban Streams: Advancing Urban Watershed Hydrology through Innovative Field and Modeling Approaches on Monday, 2 November 2015 at 2:25 pm in Room 342 (Baltimore Convention Center).

HYDROLOGIC RESPONSE TO WATERSHED METRICS DESCRIBING URBAN DEVELOPMENT AND MITIGATION WITH STORMWATER CONTROL MEASURES

BELL, Colin D., Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, MCMILLAN, Sara K., Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2093, JEFFERSON, Anne J., Department of Geology, Kent State University, Kent, OH 44242 and CLINTON, Sandra, Department of Geography and Earth Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, bell137@purdue.edu

Stormwater control measures (SCMs) are designed to mitigate changes in hydrologic response to hydrometeorological forcing caused by urban development. Total imperviousness (TI) is a metric that effectively quantifies this urban development, but does not contain information about the extent of SCM mitigation within the watershed. The hydrologic records of 16 urban watersheds in Charlotte, NC spanning a range of TI (4.1 to 54%) and mitigation with SCMs (1.3% to 89%) were analyzed to identify which of a suite of easily-determined watershed metrics best predict hydrologic behavior. We tested the watershed metrics TI, percent forested coverage, impervious area unmitigated by SCMs, effective impervious area, percent SCM-mitigated area, and a newly-developed metric called the mitigation factor. Linear models proved TI to be the best predictor of the 10th, 30th, 50th, 70th, and 90th percentiles of the distributions of peak unit discharge and rainfall-runoff ratios. In addition, TI was the best predictor of a watershed’s ability to buffer small rain events and the rate at which a stream responds once that buffering capacity is exceeded. Additional variables describing hydrograph record flashiness and water yield were best correlated to unmitigated imperviousness and forest coverage, respectively. For the range of watersheds considered, simple metrics that quantify SCM mitigation of both total watershed area and impervious area were neither the strongest primary control nor a consistent, secondary control on storm event behavior across sites. The dominance of TI as a control on hydrology over metrics of stormwater mitigation could either be attributed to the range of sites considered (14 out of 16 sites had less than 20% SCM mitigated area) or because the watershed metrics were not able to consider the spatial arrangement of impervious surfaces and SCMs. Our results have implications for policy makers designing standards that seek to minimize stream ecosystem degradation due to hydrologic disturbances from urbanization.

Post-doc Opportunity in Watershed Modeling at Kent State University

This position has been filled. Thanks for your interest.

Post-doctoral Associate in Watershed Modeling

A post-doctoral position focusing on hydrologic modeling of urban watersheds is available in the Department of Geology, Kent State University, in the lab of Anne Jefferson (http://all-geo.org/jefferson/research/). The successful candidate will have experience using RHESSys or another distributed watershed model and interest in applying their skills to questions about the effects of green infrastructure and climate change in urban areas. The post-doc will be expected to contribute to research design and undertaking, publication, and pursuit of external funding. There will also be the potential to develop additional projects building on the strengths, interests, and expertise of the successful candidate. The post-doc will have access to a wealth of data sets, field sites and instrumentation; an interdisciplinary, collaborative group of researchers and external partners focused on urban ecosystems; and a campus mentoring program for postdocs.

Kent State University (www.kent.edu), the second largest university in Ohio, is a state-supported, doctoral degree granting institution ranked as ‘high research’ by the Carnegie Foundation. The Department of Geology (www.kent.edu/geology/) has a strong graduate program (both MS and Ph.D. degrees) in both applied and basic areas of geologic research. The city of Kent combines the eclectic atmosphere of a small midwest college town with easy access to major metropolitan centers, including Cleveland, Akron, Columbus, and Pittsburgh.

Salary will be commensurate with experience and includes a competitive benefits package. Funding is initially available to support 1.5 years of work and opportunities will be sought to extend the support. If you are interested in learning more about the position, e mail Anne Jefferson (ajeffer9 at kent edu) with your CV, a description of your interests and experiences, and contact information for three people willing to serve as references. Review of applications will begin March 1st and continue until the position is filled. Kent State University is an Affirmative Action/Equal Opportunity Employer and encourages interest from candidates who would enhance the diversity of the University’s faculty.

Lost Rivers documentary showing in Kent!

I’m super-excited! Super super excited. I’ve just found out about a new documentary on Lost Urban Rivers! The trailer looks great (see below). And it’s showing in Kent! This week!

Lost Rivers is a new documentary by Montreal-based Catbird Films, and it tells the story of how cities built around water, then built over it “losing” the rivers, and how today we are starting to uncover those rivers again. The film was released earlier this year, and there’s only been two other screenings of it in the US so far. And totally unbeknownst to me, the third US screening is here in Kent, Ohio on Friday (April 19th) as part of the Who’s Your Mama? Environmental Film Festival. The film festival runs from 5 to 9 pm, with lots of great shorts, and Lost Rivers is the featured documentary, which will show at 7:30 pm. The film festival is in the Kiva on the Kent State Campus, and admission is $7, $5 for students and seniors, or free for kids under 12. There will also be local food tastings and booths by local environmental organizations, including Kent State’s student group CRICK.

Lost Rivers – OFFICIAL TRAILER from Catbird Productions on Vimeo.

Doesn’t it look great? I’ll definitely be at the screening on Friday, and I hope I’ll see some of my students there as well (though I know many will be on a field trip). In any case, I’ll report back, but I’m hopeful that by the next time I teach Urban Hydrology, I’ll have a copy on DVD and be able to show it to my class. Whee!

Collecting Data on the Cuyahoga River in Kent

Next week my Urban Hydrology class embarks on their first project: exploring the potential water quality changes in the Cuyahoga River as it flows through the City of Kent, which is really the first good-sized town on its path to Lake Erie.

Here’s a summary of what we’ll be doing, and you can click through to the attached document to get more details.

Beginning February 5th, we’ll be collecting near-daily water quality measurements of Cuyahoga River water as it flows through Kent. Using the data we collect, we’ll attempt to answer the following questions:
• How does water quality change as the river flows through an urban area?
• How does water quality vary with respect to discharge in the Cuyahoga River?

Each student will sign up for one weekday on the class calendar. On the assigned day, that student will be responsible for taking a suite of measurements at 2-4 locations. The measurements we will take are (1) turbidity, (2) specific conductance, and (3) temperature and we will also collect water samples for later analysis on the Picarro water isotope analyzer. Each student will be required to take one set of measurements at the base of the steps just upstream of Main Street and one set of measurements at the beach just downstream of Summit Street. Students with access to cars are also encouraged to take measurements at the River Bend Road boat launch (at Kent’s upstream end) and at the Middlebury Road boat launch (at Kent’s downstream end). Details of each measurement technique and each site are [in the linked document].

Trail and stairs going down to river. Patches of snow and ice in the scene.

River access just upstream of the Main Street bridge in Kent. This is one of the spots we’ll be using to sample the river.

Reflecting on my cities and their water

This week’s mini-assignment for my urban hydrology class reads thus: “In 1-2 paragraphs, describe your hometown (or some other city you know well) in terms of its location, size, and form and why it is that way (i.e., historical context). Then write a paragraph describing your city’s relation to water. For example, what is the water supply and where is wastewater disposed? Are there local water bodies or water issues important to the community? You don’t need to include references with your assignment, but you should check your facts if you are unsure about anything.”

Because I’m a water geek, and I wanted to model a good response to these questions, I present not one, but two, reflections on cities I’ve known well and how those cities relate to water.

Winona, Minnesota

I grew up in Winona, Minnesota, a town of about 28,000 people in the southeastern corner of Minnesota. The main part of the city is situated in the middle of the Mississippi River floodplain, with the main channel on one side and a former channel (now lake) on the other. The Winona area was inhabited by Native Americans for millennia, prior to its establishment by white settlers in 1851. Winona’s location along the river made it an important link for railway and steamboat transportation, and Winona was the second place on the Mississippi to be crossed by a railroad bridge (opened in 1891). Winona grew rapidly, and by 1900 had almost 20,000 residents. Winona was a major sawmilling center (with logs floated down the river to the mills), and Winona is still a major port on the river for loading agricultural products onto barges. In southeastern Minnesota, the Mississippi River sits in a ~500 foot deep valley, so as the city has grown larger, it has spread outwards into tributary valleys and up onto the plateau. However, most of the population still lives on the floodplain, and most of the developed area (including pretty much all of the industrial and commercial areas) is in the valley bottom.

As is apparent by the paragraph above, Winona as a city is intricately tied to the Missisisippi River, physiographically and economically. River recreation (boating, fishing, duck hunting) is also a major past-time (and economic contributor) for Winonans. The river holds pride of place in town, but it was also a source of major and frequent flooding until 1985 when an 11-mile levee was built surrounding the town. Other than the occasional flood (now more a curiosity than a catastrophe), periodic public engagement with dredging of sand from the river bottom, and the enjoyment of boat trips on the river, I would say that Winonans’ aren’t particularly attentive to water issues, because it is abundant and out of their way. The city gets its water supply from a Cambrian sandstone aquifer several hundred feet below town, where water is abundant and good quality. It disposes its treated wastewater into the river at the downstream end of town. The big water issue I remember growing up, was about water quality in the Lake, which was quite degraded by the invasive exotic, Eurasian water milfoil. There is actually a water issue that has cropped up over the last several years in the region, which is getting local attention, and that is the mining of “frack sand” from the local sandstone formations. This is getting attention because of problems with heavy truck traffic in town, blowing sand from exposed storage piles, and from destruction of rural areas where the sandstone is being mined. However, to me, it is ultimately a water issue, because those sandstone formations are the regional aquifers. It’s not clear to me yet what effect the mining will have on local or regional water quality, but it seems like an issue to watch.

Charlotte, North Carolina

I spent five years living in Charlotte, which is the largest city in North Carolina, with a metropolitan population of 1.8 million people. Charlotte is a major financial center, and also the home of NASCAR. The city was founded around 1755 at the intersection of two Native American trading paths, and it was a “hornet’s nest of rebellion” during the American Revolution, being the first place that city leaders signed a declaration of independence from Great Britain. Charlotte’s history includes being close to the site of the first gold boom in the US, and becoming a major cotton processing center and railroad hub. Banking and NASCAR rose to prominence since the 1970’s, and the region has experienced explosive population growth (and urban sprawl) since then. The population of the city itself has gone from 241,000 in 1970 to over 730,000 in the 2010 census. There is a relatively small, high density city center surrounded by miles of low density residential, commercial, and industrial development. The gentle rolling topography of the Piedmont forms no barriers to the geographic expansion of the urban area. Several small towns have been agglomerated by the urban area, and many people commute from these communities into the city center or across the city.

The Catawba River, which has a watershed area of 3343 miles upstream of the South Carolina border (Charlotte’s southern boundary), flows through the urban area a few miles west of downtown Charlotte. The River is impounded in a series of reservoirs used for hydroelectric generation by Duke Energy, and was one of the first rivers in the country used for that purpose. Most of the land along the river is privately owned by relatively affluent people, and there are only a few public parks on the reservoirs. Power-boating recreation is popular with those along the river, but swimming is banned in the county in which Charlotte sits, because of concerns about liability. The river forms the water supply for the city, because the fractured crystalline rocks in the area don’t support pumping of large groundwater volumes. Wastewater is treated and disposed of back into the river (farther downstream) or into local streams. There are a number of small urban streams that flow through the city, and these streams are quite prone to flooding during heavy rainstorms. The city and county have undertaken a major stream restoration and stormwater management program to try to reduce flooding hazards, and a series of greenways have been established along the some of the streams. When I moved to Charlotte in 2007, we were in the middle of an intense drought, and subject to limitations on outdoor water use. However, as soon as the drought lifted, local water conservation mindfulness seemed to disappear too. There is an illusion of abundance of water in the southeastern US, even though as population grows water supplies are becoming stressed (Atlanta is a stark example of this). In a recent book, author Cynthia Barnett highlighted Charlotte as a prime example of a city that was “disconnected” from its water supply, meaning that the people of the area lacked a water culture or ethic that would encourage conservation and sustainable use.

I probably spent about 20 minutes writing each piece, but I’m fairly familiar with the water issues and setting in each area (see above: I’m a water geek). So it might take you a bit longer to do a similar amount of writing. One essay is 499 words, and the other is 528 words, but you could write less and still cover the relevant information. I haven’t included hyperlinks to lots of sources here, because I didn’t require that of my students, but I might go back later and add them, because it just seems like wasting the capabilities of the web to not do so.