Does a Bear GPS in the Woods? Evaluating the use of surveying-grade GPS in challenging terrain Jason Flagg Syracuse University

Motivation Test effectiveness of survey-quality GPS equipment in challenging terrain Establish important positions at HBEF for GIS Establish control points for future surveys (existing USGS benchmarks)

Equipment Info Six Trimble 5700 series receivers Simultaneous measurement at base and 1 - 5 rovers “Post-processing” of data produces network of baselines connecting points

Accuracy Known point in Lincoln measured from Plymouth as if unknown Northing (m) Easting (m) Measured 172381.458 298204.799 Published 172381.445 298204.808 Diff. 0.016 m Error 1 in 1,942,000

Precision Under Good Conditions Marker at HB headquarters measured from both Lincoln and Plymouth Northing (m) Easting (m) Lincoln 160408.029 297235.163 Plymouth 160408.049 297235.162 Diff. 0.020 m Precision 1 in 940,000

Precision Under Adverse Conditions USGS benchmark along Hubbard Brook Rd. measured three separate times Base setup at: Northing (m) Easting (m) Elevation (m) Lincoln (5/15) 159161.955 291746.797 537.879 HBHQ (5/15) 159161.960 291746.798 537.890 HBHQ (5/17) 159161.970 291746.806 537.992 St. Dev. (m) 0.007 0.006 0.062

Precision Under Adverse Conditions Precision also measured by “loop closure” Three legs of a triangle measured independently Closure error for this triangle was 0.015 – 0.016 m over total distance of 11,500 m

Other Measurements Freeze Plots Weirs Rain Gages “Wedge” Plots Watersheds 1 & 6 Boundaries Open to more suggestions

Special Thanks To: Chris Johnson Nate Jones