Beard's Creek Impoundment Drawdown [2018-05-30]
Aerial imagery of the Beard's Creek impoundment drawdown in Durham, NH off of Coe Dr. The drawdown occurred around May 7, 2018, and consisted of removing stop logs from the Route 108 dam to permanently lower the water level in the impoundment by 2 feet. This imagery was collected May 30, 2018, soon after the drawdown, and illustrates the initial condition of the exposed sediments throughout the previously impounded area. The orthomosaic was created using 254 images collected at 250 ft above ground level using a DJI Phantom 3 Professional small unmanned aerial system. The orthomosaic has a spatial resolution of 3.18 cm/pix. Automated flight paths were executed using the Litchi flight app that provided sufficient and consistent side and frontal overlap between nadir images. Flight paths were planned using DJIFlightPlanner. Flight paths to collect sets of angled (20 degrees from nadir) photos were used to supplement the nadir images for structure-from-motion photogrammetry. The same flight paths were used to collect this imagery as the July 11, 2018 imagery. Images were processed in Agisoft PhotoScan Professional. Imagery was georeferenced using the drone's built in gps (WGS84) and is sufficient for illustrative purposes to overlay with the July 11, 2018 imagery but will not perfectly align. Private residences and yards have been cropped out of the imagery. Thanks to Scott Greenwood, Sonnet Agran-St.Pierre, & Keelin Berger for assisting fieldwork and processing.
The first file (jpg) is a screenshot to provide a preview on figshare. The second file (tif) is the full resolution, georeferenced orthomosaic.