Submitted to: Joint Federal Interagency Sedimentation and Hydrologic Modeling
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2009
Publication Date: 6/27/2010
Citation: Nouwakpo, S., Huang, C., Frankenberger, J.R., Bethel, J. 2010. A simplified close range photogrammetry method for soil erosion assessment. Joint Federal Interagency Sedimentation and Hydrologic Modeling. http://acwi.gov/sos/pubs/2ndJFIC/Contents/SP07_Nouwakpo_01_03_10_paper.pdf. Interpretive Summary:
Technical Abstract: With the increased affordability of consumer grade cameras and the development of powerful image processing software, digital photogrammetry offers a competitive advantage as a tool for soil erosion estimation compared to other technologies. One bottleneck of digital photogrammetry is its dependency on accurately measured control points, which are usually obtained using survey grade equipment such as RTK-GPS. Also, even though many soil erosion studies have used digital photogrammetry for soil erosion assessments; little studies have compared this technology to any other technologies. In this paper, we propose a digital photogrammetry method for control points coordinates acquisition without the need of any survey grade equipment. The method, based on a constrained bundle block adjustment, was successfully tested on a 2m x 2m soil box. We obtained high quality control points with a Length Measurement Error of 1.3 x 10-3m and mean deviations from the different axes obtained were SX = ± 0.011 m/m, SY = ± 0.009 m/m and SZ = ± 0.002 m/m. We also present in this paper an extensive comparison between laser scanner technology and digital photogrammetry in producing DEMs and detecting soil surface elevation changes. We found that the agreement between Digital Elevation Models (DEM) from both technologies improved as the soil surface became smoother and the amount of soil loss increased. Our results suggest that digital photogrammetry is suitable for field applications such as gully geometry measurement, erosion measurement on highly eroding areas, stream bank erosion, and gully headcut evolution, etc.