Ph.D. student Colin Bell will be presenting the following poster at the American Ecological Engineering Society meeting this week in Syracuse, New York.
Using Watershed Modeling to Optimize Management of Urban Stormwater to Control Stream Nitrogen
Dr. Sara McMillan
Dr. Christina Tague
Dr. Anne Jefferson
Dr. Sandra Clinton
Urban infrastructure expansion causes the alteration of hydrologic and nutrient regimes, elevating nitrogen (N) concentrations in the streams that receive stormwater runoff. The inclusion of stormwater Best Management Practices (BMPs) in urban watersheds has been found to help ameliorate these problems by retaining water and reducing N concentrations through denitrification and uptake. The Regional Hydro-Ecological Simulation System (RHESSys) is currently being used to test the impact of different BMP implementation strategies and fertilizer application regimes to simulate their effects on instream N in an urbanizing, residential watershed in Charlotte, NC. RHESSys is a distributed, process-based model that simulates natural and anthropogenic N and carbon (C) sources, processing and export. Watershed characterization of two watersheds with contrasting land uses (suburban and forested), along with field monitoring of instream and BMP water chemistry is currently being completed. This will allow us to parameterize the influences of existing BMPs on instream N concentrations, and allow RHESSys to scale up their observed functionality. RHESSys will test multiple, spatially-explicit scenarios to identify the combination of N loading and BMP treatment that minimizes aquatic ecosystem degradation so that land developers can urbanize responsibly.
I will be at the CUAHSI 3rd Biennial Colloquium on Hydrologic Science and Engineering on July 16-18, 2012 in Boulder, Colorado. I’ve been asked to speak in a session on the co-evolution of geomorphology and hydrology. This is a cool opportunity for me, as I’ve been thinking about co-evolution in both volcanic landscapes and Piedmont gullies for the past couple of years. I’m going to attempt to stitch those two very different landscapes and timescales together in one conceptual framework in the talk, and I guess we’ll see how it goes.
Timescales of drainage network evolution are driven by coupled changes in landscape properties and hydrologic response
Anne J. Jefferson
In diverse landscapes, channel initiation locations move up or downslope over time in response to changes in land surface properties (vegetation, soils, and topography) which control the partitioning of water between subsurface, overland, and channelized flowpaths. In turn, channelized flow exerts greater erosive power than overland or subsurface flows, and can much more efficiently denude and dissect the landscape, leading to altered flowpaths and land surface properties. These feedbacks can be considered a fundamental aspect of catchment coevolution, with the headward extent of the stream network and landscape dissection as prime indicators of the evolutionary status of a landscape.Drainage network evolution in response to landscape change may occur over multiple timescales, depending on the rapidity of change in the hydrogeomorphic drivers. Climate and lithology may also modify the rates at which drainage networks respond to change in land surface properties. On basaltic landscapes, such as the Oregon Cascades, timescales of a million years or more can be necessary to evolve from an undissected landscape with slow, deep groundwater drainage to a fully-dissected landscape dominated by shallow subsurface stormflow and rapid hydrograph response in streams. This evolution seems to be driven by a slow change in land surface properties and permeability as a result of weathering, soil development, and mantling by low permeability materials, but may also reflect the high erosion resistance of crystalline bedrock. Conversely, rapid or near-instantaneous changes in land surface properties , such as accompanied the beginning of intensive agriculture in the southeastern Piedmont, can propagate into rapid (1-10 year) changes in channel network extent on clay-rich soils. Where agriculture has been abandoned in this region and forests have regrown, downslope retreat and infilling of extensive gully networks is occurring on decadal timescales.
Earth Science M.S. student, Alea Tuttle, will defend her thesis
POST-PROJECT EVALUATIONS OF URBAN STREAM RESTORATION SITES IN THE SOUTHEASTERN PIEDMONT: STREAMBED SEDIMENT DENITRIFICATION AND GEOMORPHIC COMPLEXITY
on Monday, April 30th, 2012 at 9:30 am in the 4th floor conference room of McEniry Hall on the UNC Charlotte campus.
Alea has been primary advised by Dr. Sara McMillan and I have been her co-advisor. I’ve also had the pleasure of having Alea as my teaching assistant in Fluvial Processes and Hydrogeology this year. Alea will be remaining at UNCC this summer to act as a technician on a newly-funded project focused on floodplains. We know that she will have great success wherever she heads to after grad school.
I’m not claiming credit for this project, as it was as undergraduate summer research project advised by my collaborator Sara McMillan, but it is one tangible bit of results that have come out of our NSF-funded stormwater project. More good things are coming soon.
The following poster was presented at the AGU 2011 fall meeting.
The influence of stormwater management practices on denitrification rates of receiving streams in an urban watershed
AU: *Cronenberger, M S
AF: Environmental Sciences, Winthrop University, Rock Hill, SC, USA
AU: McMillan, S K
AF: Engineering Technology, University of North Carolina at Charlotte, Charlotte, NC, USA
Increasing urbanization and the subsequent disruption of floodplains has led to the need for implementing stormwater management strategies to mitigate the effects of urbanization, including soil and streambank erosion, increased export of nutrients and contaminants and decreased biotic richness. Excessive stormwater runoff due to the abundance of impervious surfaces associated with an urban landscape has led to the ubiquitous use of best management practices (BMPs) to attenuate runoff events and prevent the destructive delivery of large volumes of water to stream channels. As a result, effluent from BMPs (i.e. wetlands and wet ponds) has the potential to alter the character of the receiving stream channel and thus, key ecosystem processes such as denitrification. The purpose of this study was to determine the extent to which BMPs, in the form of constructed wetlands and wet ponds, influence in-stream denitrification rates in the urban landscape of Charlotte, NC. Four sites, two of each BMP type, were evaluated. Sediment samples were collected upstream and downstream of the BMP outflow from May-July 2011 to determine the effect of wetland discharge on in-stream nitrogen removal via denitrification. Denitrification rates were determined using the acetylene block method; water column nutrient and carbon concentrations and sediment organic matter content were also measured. Generally, wetland sites exhibited higher denitrification rates, nitrate concentrations and sediment organic matter content. Our work and others has demonstrated a significant positive correlation between nitrate concentration and denitrification rates, which is the likely driver of the higher observed rates at the wetland sites. Geomorphology was also found to be a key factor in elevated denitrification rates at sites with riffles and boulder jams. Sediment organic matter was found to be higher downstream of BMP outflows at all four sites, but demonstrated no significant relationship with denitrification rates. We are continuing to investigate these spatial (e.g. BMPs, streams) and temporal (e.g. storm pulse, delayed wetland release) patterns, particularly in the context of factors that influence the specific drivers of denitrification. Understanding these patterns is critical to managing stormwater in urban landscapes as we aim to improve water quality while enhancing ecosystem functions.
Join the exciting Ecology and Biogeochemistry of Watersheds research group at UNC Charlotte in learning about the effects of stormwater management on urban stream ecosystems. We are looking for one or more student research assistants for full or part-time work. This is a great opportunity for students looking for hands-on research experience and will be a good resume boost for those intending to go to grad school.
The research assistant will be responsible for helping with some or all of the following:
- Maintaining field equipment including autosamplers, water level loggers, and temperature probes
- Collecting discharge (streamflow) data and water samples during and following storms and wet weather
- Assisting with sediment, water and biological sampling in the field and lab
- Assisting with laboratory tasks, including sample preparation and analysis
- Maintaining instrument logs and good records of field and laboratory measurements
We are searching for students interested in part-time or full-time work for the summer. There is also the opportunity to begin work immediately and continue into the next academic year on a part-time basis. Your summer schedule should have enough flexibility to allow you to participate in field work as weather conditions dictate. You must provide your own transportation to and from field sites, but you will be reimbursed for gas. Research assistants will be paid $10/hour. While desirable, previous experience is not required for these positions.
To apply for these positions, please email your (1) resume, (2) list of relevant coursework, (3) list of past field and research experiences, and (4) availability for full-time or part-time work in the spring, summer and fall to Sara McMillan (smcmillan at uncc dot edu), Anne Jefferson (ajefferson at uncc dot edu), or Sandra Clinton (sclinto1 at uncc dot edu). Incomplete applications will not be reviewed. If you have questions about the work, please email us before applying. You can learn more about our group here: http://coefs.uncc.edu/smcmil10/research/.
We will begin considering applications immediately.
I’m working on a review paper on evolution of volcanic ocean islands coming out of the Chapman Conference on the Galapagos I participated in last summer. Rather handily, the conference organizers have put together a nice website with all of the talks, posters, and field trip guides. If you are interested in any of the earth science aspects of volcanic ocean islands, ridge-plume interactions, etc., check out the website. Later this year there will also be an AGU monograph arising from the Conference. I’ll post details when it is published.
Some of our students are in the field this week, injecting Cl- and Br- into a restored reach and an unrestored reach in tributaries of Beaver Dam Creek. Our goal is to understand the role of wood jams versus restoration structures in promoting stream-hyporheic exchange.
In the photo are Alea, Xueying, and Mackenzie. Photo by Brittany. They’ve got it so capably handled they didn’t even need Sandra or I out there with them today, but I’m going tomorrow for an excuse to be in the field as much as anything.
- climate change
- doing science
- headwater streams
- lab news
- landscape evolution
- natural hazards
- past worlds
- stream temperature
- student opportunities
- tropical cyclones
- unnatural hazards
- urban watersheds
- watershed hydrology