HR: 1340h
AN: H43A-0357    [Abstracts]
TI: Comparison of Three Measurement Techniques for Estimation of Sediment Transport Using Channel Morphology
AU: * Bird, S A
EM: sbird@fluvial-systems.com
AF: Fluvial Systems Research Inc., No. 179, 106-1656 Martin Dr., White Rock, BC V4A 6E7 Canada
AU: Zimmermann, A E
EM: andre.zimmermann@mail.mcgill.ca
AF: Depatment of Geography, University of British Columbia, 1984 West Mall, Vancouver, BC V6T 1Z2 Canada
AU: Blocka, D L
EM: dblocka@fluvial-systems.com
AF: Fluvial Systems Research Inc., No. 179, 106-1656 Martin Dr., White Rock, BC V4A 6E7 Canada
AU: Hassan, M A
EM: mhassan@geog.ubc.ca
AF: Depatment of Geography, University of British Columbia, 1984 West Mall, Vancouver, BC V6T 1Z2 Canada
AU: Hogan, D L
EM: Dan.Hogan@gems9.gov.bc.ca
AF: Research Branch, BC Ministry of Forests, c/o Fisheries Research, 2204 Main Mall, Vancouver, BC V6T 1Z4 Canada
AB: Documenting changes in channel morphology has traditionally been achieved through periodic resurvey of permanently monumented cross sections. In British Columbia, 197 cross sections in eight study areas of Carnation Creek have been resurveyed annually since 1970 to measure changes in bed material storage in response to forest harvesting. Spatial interpolation between cross sections allows production of a digital elevation model (DEM), and subtraction of multi-temporal DEMs in a geographical information system (GIS) enables high-resolution estimates of changes in stored sediment. However, the quality of each DEM depends on the spacing between cross sections relative to the local variability in channel morphology. Recent advancements in digital photogrammetry enable acquisition and analysis of very large data sets with the potential for increased precision and accuracy compared to conventional ground surveying techniques. In this study, independent DEMs derived from seven cross sections and from digital photogrammetry are each compared to a high-resolution total station survey of a single riffle-pool sequence of Carnation Creek. The mean error of the DEMs derived from cross sections and from photogrammetry was -0.032 and -0.035 m, respectively. Errors in the DEM derived from photogrammetry were most apparent in relatively deep water ($>$ 0.5 m) and under overhanging vegetation. Errors in the DEM derived from cross sections were most apparent near the mid-point between cross sections and along the streambanks. Experimental removal of cross sections from the analysis suggests that errors remain relatively stable for a cross section spacing of up to about one bankfull width. The spatial distribution of errors inherent to each technique has important implications for estimates of sediment transport derived from the morphological method. Cross sections are most effective when the channel is relatively straight, bank heights are low, and the morphology is simple. Photogrammetry is most effective when water depths are relatively low, vegetation cover is minimal, and the morphology is complex.
UR: http://www.fluvial-systems.com/aguposter04
DE: 1824 Geomorphology (1625)
DE: 1224 Photogrammetry
DE: 1294 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting