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Post-Dam Drawdown Map of Vegetation Cover Changes at Beard's Creek (May 30th vs July 11th, 2018)

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posted on 01.11.2019 by Alexandra Evans, Kevin Gardner
A map of changes in vegetation cover at Beard's Creek impoundment in Durham, NH, USA post-dam drawdown. Newly vegetated areas (shown in yellow) grew in between May 30th and July 11th, 2018, which are the two dates the small unmanned aerial system imagery was collected. The Green Leaf Index (GLI) was used to map binary vegetative vs. non-vegetative cover and changes in cover on a pixel basis (Louhaichi et al. 2001):

GLI = (2*G-R-B)/(2*G+R+B).

The GLI threshold to indicate green vegetation was set to 0.02 for this imagery. The binary vegetation cover maps, one from each drone flight date, were used to produce the single map of vegetation cover changes via the raster calculator in QGIS.

Original orthomosaics of the impoundment used to make this vegetation cover change map (with sUAS imagery details):

This figure was made using resources from an NSF EPSCoR funded project “RII Track-2 FEC: Strengthening the scientific basis for decision-making about dams: Multi-scale, coupled-systems research on ecological, social, and economic trade-offs”. Support for this project is provided by the National Science Foundation’s Research Infrastructure Improvement NSF #IIA-1539071. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Louhaichi, M., Borman, M. M., & Johnson, D. E. (2001). Spatially located platform and aerial photography for documentation of grazing impacts on wheat. Geocarto International, 16(1), 65-70.

This work was presented by the author at the 5th North East Graduate Student Water Symposium on September 7, 2018.

Poster Title: "Observing the Transition of Beard's Creek Pond from Lentic to Lotic Conditions Post-Dam Drawdown"
Authors: Alexandra Evans, Scott, Greenwood, Kevin Gardner
*All authors associated with University of New Hampshire, Civil & Environmental Engineering Department


NSF #IIA-1539071