The Watershed Hydrology lab will be out in force for the Geological Society of America annual meeting in Vancouver in October. For the last few days, we’ve been sharing the abstracts of the work we are presenting there.
AFTER THE DAM COMES DOWN: GROUNDWATER-STREAM INTERACTIONS AND WATER QUALITY EFFECTS OF RESTORED AND UNRESTORED REACHES IN NORTHEASTERN OHIO
BROWN, Krista Marie, Geology, Kent State University, Kent, OH 44240, firstname.lastname@example.org and JEFFERSON, Anne J., Department of Geology, Kent State University, 221 McGilvrey Hall, Kent, OH 44240
Over that past decade, dam removals have become increasingly popular, as many dams near the end of their life expectancy. With an anticipated increase of dam removals in coming years, this study aims to develop an understanding of groundwater-stream interactions and water quality in former reservoirs after dam removal. Low head dams were removed in 2009 on Plum Creek and Kelsey Creek, tributaries to the Cuyahoga River. Kelsey Creek reservoir remains unaltered and consists of a stream channel flowing through riparian-wetland environments, while Plum Creek reservoir underwent channel restoration in 2011. At Kelsey Creek, 20 piezometers and 3 wells were installed within the former reservoir. Since October 2013, hydraulic heads have been recorded semi-weekly for aquifer modeling and water samples have been taken in the wells and stream. Water quality is being evaluated with field-measured parameters and ion chromatography. Plum Creek is being used to understand the water quality effects of channel restoration.
At Kelsey Creek, interaction between the stream and shallow groundwater is evident. The stream tends to contribute shallow groundwater flow toward the western side of the site and north, parallel to the stream. The well closest to the stream shows variability in specific conductance, indicating bidirectional groundwater-stream exchange and all wells show rapid response to precipitation events. Hydraulic conductivity calculated using the Hvorslev method ranged 2.84×10-2to 7.38×10-6 m/s and poorly correlate with the bulk sediments in Kelsey Creek.
Despite the wetland and groundwater-stream exchange in the unrestored Kelsey Creek, there is little change in stream water quality within the former reservoir site, similar to the restored Plum Creek site. This suggests that there is little water quality benefit to be gained from stream restoration at dam removal sites. Left unaltered, Kelsey Creek provides flood control and groundwater recharge in wetland areas.
Next week, the Watershed Hydrology Lab will be well represented at the CUAHSI 2014 Biennial Colloquium. We’ll be presenting four posters, so here come the abstracts…
After the dam comes out: groundwater-stream interactions and water quality impacts of former reservoir sites
Krista Brown and Anne Jefferson
Over that past decade, dam removals have become increasingly popular, as many dams near the end of their life expectancy. With an increasing number of anticipated dam removals coming in the near future this study aims to develop an understanding of groundwater-stream interactions and water quality in former reservoir sites after dam removals have occurred. Low head dams (~2 m) were removed in 2009 from Plum Creek in Kent, Portage County, Ohio and on Kelsey Creek in Cuyahoga Falls, Summit County, Ohio. Kelsey Creek reservoir has been unaltered since the dam removal and consists of a stream channel flowing through riparian- wetland environments, while Plum Creek reservoir underwent channel restoration in 2011. At Kelsey Creek, 20 piezometers and 3 wells were installed in the stream and riparian areas. Pressure transducers were also deployed in each well and stream from November 20, 2013 to January 5, 2014. Hydraulic conductivity was calculated using the Hvorslev method. Since October 2013, hydraulic heads have been recorded semi-weekly and water samples have been taken in the wells and stream. Water quality is being evaluated with field-measured pH, temperature, specific conductance, and dissolved oxygen, and ion chromatography of chloride, bromide, nitrate, sulfate and phosphate concentrations. Plum Creek is being used to understand the water quality effects of channel restoration at former reservoir sites.
At Kelsey Creek, hydraulic conductivity ranges five magnitudes, from 10?2 to 10?6 m/s, but wells near the channel, in an off-channel wetland, and on an adjacent hillslope respond similarly during high flow events. However, the well closest to the stream shows substantial variability in specific conductance, indicating bidirectional groundwater-stream exchange. Despite the wetlands and presumed greater groundwater-stream exchange in the unrestored Kelsey Creek, stream water quality is similar to the restored Plum Creek site. This suggests that the water quality measures considered here should not determine whether to restore channels within former reservoir sites. Findings from this research may be applicable when considering options for future dam removal sites.
I’ll be at the 2013 Upper Midwest Stream Restoration Symposium in LaCrosse, Wisconsin in February. Even though the conference focuses on the Upper Midwest (of which Ohio is a part), I’m going to be talking about work from the southeastern US. Of course, the conference will be a great chance for me to learn from and make connections with stream restoration practicioners and scientists in the Midwest. I’m really looking forward to it, and hopefully they won’t call me out as a carpetbagger. I actually grew up ~25 miles from the conference location. Here’s the abstract.
Evaluating the success of urban stream restoration in an ecosystem services and watershed context
Anne Jefferson1, Sandra Clinton2, Mackenzie Osypian3, Sara McMillan3, Alea Tuttle2
1. Department of Geology, Kent State University
2. Department of Geography and Earth Sciences, University of North Carolina at Charlotte
3. Department of Civil Engineering, University of North Carolina at Charlotte
In urban watersheds, the capacity of streams to provide essential ecosystem services is often limited as a result of channel straightening, incision and removal of geomorphic features. Stream restoration seeks to provide stream stability while reestablishing ecosystem services, but restoration alone may not mitigate the effects of watershed land-use change and urbanization. Stream restoration activities frequently impact transient storage and hyporheic exchange, the processes by which water movement is slowed down or temporarily detained at the surface or in the streambed. Transient storage and hyporheic exchange zones are important regulators of nutrient retention and stream temperature, and they harbor diverse biological communities. However, it is unknown how successful stream restoration activities are at creating ecologically effective storage and exchange zones that promote improved water quality and nutrient retention. In a series of studies in Charlotte, North Carolina, we have evaluated restored and unrestored streams to quantify and compare transient storage and nutrient retention. Our goal is to evaluate the relative success of restoration activities for ecosystem services in urban and forested watersheds. We measured increased transient storage and greater variability in upwelling and downwelling vertical hydraulic gradients in restored relative to unrestored reaches. However, restored reaches also had lower hydraulic conductivity of bed sediments, which was likely related to to restoration practices such as streambed compaction and installation of landscaping fabric and cement below structures that may reduce the magnitude of hyporheic exchanges. Restored streams also have higher water temperatures than unrestored streams. The removal of riparian vegetation and soil disturbance and compaction during the restoration process, along with continued input of nutrients from fertilizers in urban watersheds can result in a unique water quality signature in urban restored streams. Denitrification rates were variable between sites, but channel complexity and restoration of urban streams appear to increase denitrification, even though hyporheic exchange was generally low. In unrestored urban streams, allochthonous anthropogenic debris (e.g., shopping carts) may contribute to channel complexity and nutrient retention. While current practices of urban stream restoration may be successful in creating channel stability, coupling watershed-scale management of stormwater and nutrients with restoration techniques designed to enhance ecologically effective storage and exchange may be required for restoration success in a holistic sense.
One of our restored stream sites, during the summer drydown (August 2010). Beaverdam Creek watershed, Charlotte, North Carolina. Photo (c) Anne Jefferson.
A nice British video explaining the connection between rivers and groundwater. I can’t get the embed to work, so you’ll have to click through to watch: http://www.groundwateruk.org/How-Rivers-Work-Role-of-Groundwater.aspx This is why I say I study rivers AND groundwater – if you want to understand how water moves through a watershed, you’ve got to …
Major congratulations to two Watershed Hydrogeology Lab graduate students who have finished writing their MS theses and will defend them next week. Ralph McGee and Cameron Moore both started in our MS in Earth Science program in August 2009, and less than two years later they have each completed impressive MS projects on headwater streams in Redlair Forest of the North Carolina Piedmont.
Ralph McGee will present his research on “Hydrogeomorphic processes influencing ephemeral streams in forested watersheds of the southeastern Piedmont U.S.A.” on Thursday, May 12th at 10:00 am in McEniry Hall, room 111 on the UNC Charlotte campus.
The unofficial title for Ralph’s work is “Tiny Torrents Tell Tall Tales.” Watch the video below to see why.
Cameron Moore will present his research on “Surface/Groundwater Interactions and Sediment Characteristics of Headwater Streams in the Piedmont of North Carolina” on Friday, May 13th at 9:00 am in McEniry Hall, room 111 on the UNC Charlotte campus.
When Cameron started working on this project, I had thought that the story would focus on how fractured bedrock contributed to groundwater upwelling in the streams, but it turns out the small debris jams (like the one below) are the dominant driver of groundwater/stream interactions and spatial variability of channel morphology.
Looking upstream at a debris jam in Deep Creek
Faculty, students, and the public are encouraged to attend the presentations and ask Ralph and Cameron any questions they may have.