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Tanyard Branch. An exercise in stream restoration and redesign. Given by: Sarah Hibbs September 29, 2003. What is Tanyard Branch?. An Urban Stream which runs through The University of Georgia campus, beneath Sanford Stadium 50% of Tanyard Branch is piped
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Tanyard Branch An exercise in stream restoration and redesign Given by: Sarah Hibbs September 29, 2003
What is Tanyard Branch? • An Urban Stream which runs through The University of Georgia campus, beneath Sanford Stadium • 50% of Tanyard Branch is piped • Channel banks and streambed are highly eroded • Water does not meet water quality regulations • Poor habitat for insects and aquatic life • Stream is cut off from human interaction
History of Tanyard Branch 1874 Map of Athens, Georgia (Tanyard Branch highlighted in blue)
1993 aerial photo of Athens, Georgia and the University of Georgia campus
Major Concerns • Stormwater • Problems—for urban streams and for Tanyard Branch • Strategies for repair and management • Vegetation and aquatic habitat • Geomorphic reference conditions, watershed and hydrologic assessment
Stormwater concerns in an urban setting • Channel instability—eroded banks and stream beds • Increased peak storm flows • Reduced baseflows • Water quality impairment (including increased temperatures, toxic pollutants, nutrients, turbidity and sediment • Habitat degradation • Biological impairment
Stormwater and Tanyard Branch Lumpkin Tanyard culvert November 10th Lumpkin Tanyard culvert Culvert filled to capacity, September 14th
Stormwater and Tanyard Branch Sanford Tanyard culvert Culvert filled to capacity, September 14th Sanford Tanyard culvert November 10th
Traditional Methods Conveyance—storm drains, street gutters, culverts—anything to channelize to the nearest stream Detention—wet and dry detention ponds, stormwater wetlands Desirable Methods Infiltration—shifts balance of water from surface water back to groundwater—uses things like rain gardens, porous pavers and green roofs. How to deal with Stormwater
Alternative stormwater strategy 1 • Cisterns that collect stormwater from rooftops and condensate from air conditioners • Retrofit sidewalks with porous paving • Include green roof design on roof upgrades of existing buildings
Alternative stormwater strategy 2 • Vegetated infiltration basins (rain gardens) with terraced inflow dissipation Water from parking lots is collected conventionally, but not shunted into a new storm sewer system.
Water from parking lot is filtered through several stilling wells, and filtered through an Alluvial fan, which slows fast moving water and allows for sediment deposit. From the alluvial fan, water is infiltrated in a series of rain gardens
Alternative stormwater strategy 3 • Floodplain rehabilitation—replace impervious surfaces in the floodplain with riparian wetlands • The floodplain is an integral part of biological habitat, as well as stormwater management
NC State’s campus stream, Rocky Branch, once had steep banks, but the floodplain has been reestablished and will soon be reforested.
Vegetation Suggestions • List of typical plant communities for the riparian zone and uplands • Drawn from other stream corridors in the Georgia piedmont
Aquatic Habitat • Clean, large sediment, consisting of pebble and cobble, for spawning and feeding • Bedrock for feeding and cover • Pools, especially deep pools, to provide refuge during drought or low flows • Riffles, for feeding and spawning, especially important for small-bodied fishes • Woody debris for feeding and cover
Geomorphic reference conditions, watershed, and hydrologic assessment • Tanyard channel is currently south of historic location—redesign incorporates the relocation back to its previous channel • Channelization (straightening) is another major problem for Tanyard branch—redesign will use a reference stream in the North Carolina piedmont (data includes: sinuosity, width:depth ratio, and meander belt width:width ratio) to replace the natural curves and meanders previously lost
Watershed assessment was conducted to assess appropriate channel size. Using a DOQQ for Clark County, watershed parameters were calculated using the ERDAS Imagine GIS software.
Tanyard Branch Redesign of Campus • Using the campus master plan, several conceptual designs were submitted with Tanyard Branch as the focus. • Changes include: Elevated road extensions, new buildings and dorms, community outreach centers and other important features to the functioning of the center of UGA’s campus
