posted on 2006-07-04, 14:49authored byJim Chandler, P. Ashmore, C. Paola, Michael J. Gooch, F. Varkaris
Imagery acquired using a high-resolution digital camera and ground survey has been used to
monitor changes in bed topography and plan form, and to obtain synoptic water surface and flow
depth information in the braided, gravel bed Sunwapta River in the Canadian Rockies. Digital
images were obtained during daily low flows during the summer melt-water season to maximize
the exposed bed area and to map the water surface on the days with the highest flows. Images
were acquired from a cliff top 125m above and at a distance of 235m from the riverbed and used
to generate high resolution orthophotos and digital elevation models (DEMs) at a ground
resolution of 0.2m, within an area 80 x 125m. The creation of digital elevation models (DEMs)
from oblique and non-metric imagery using automated digital photogrammetry can be difficult,
but a solution based on rotation of coordinates is described here. Independent field verification
demonstrated that root mean square accuracies of 0.045m in elevation were achieved.
The ground survey data representing river bed topography were merged with photogrammetric
DEMs of the exposed bars. The high-flow water surface could not be surveyed directly because
wading was dangerous but was derived by ground survey of selected accessible points and
photogrammetry. The DEMs and depth map provide high-resolution, continuous data on the
channel morphology and will be the basis for subsequent 2D flow modeling of velocity and shear
stress fields. The experience of using digital photogrammetry for monitoring river channel change
allows the authors to identify other potential benefits of using this technique for fluvial research
and beyond.
History
School
Architecture, Building and Civil Engineering
Pages
1467018 bytes
Citation
CHANDLER et al, 2002. Monitoring river channel change using terrestial oblique digital imagery and automated digital photogrammetry. Annals of the Association of American Geographers, 92(4), pp.631-644