Large river bed sediment characterization with low-cost sidescan sonar

Presented at SEDHYD 2015

Transcript

2. Sampling riverbed substrates is tough when ... ... water is too turbid or deep to image the bed from aerial platforms ... too swift or deep to wade to obtain physical samples ... spatial variability is so great its impractical to sample using conventional methods
3. Sampling riverbed substrates is tough when ... ... water is too turbid or deep to image the bed from aerial platforms ... too swift or deep to wade to obtain physical samples ... spatial variability is so great its impractical to sample using conventional methods
4. Sampling riverbed substrates is tough when ... ... water is too turbid or deep to image the bed from aerial platforms ... too swift or deep to wade to obtain physical samples ... spatial variability is so great its impractical to sample using conventional methods
5. Sidescan sonar
6. Humminbird R fishfinder
7. Low-cost, low-profile inexpensive sidescan sonar Operated by one person in any river or stream navigable by small boat. Sufficient quality for bed imaging in shallow streams Automate sonar processing, positioning, and substrate classification
8. Colorado River Scans
9. Penobscot River Scans Visual interpretations are labour-intensive, subjective and impractical for mapping large areas of riverbed
10. Substrate and non-native fish Melis and Korman, 2011
11. Colorado River in Marble Canyon Anima et al, 1998 USGS OFR: sidescan and video surveys Up to 100% change in sand coverage over a few 100 m Up to 100% change in sand coverage over 2 years
12. Substrate and non-native fish
13. Wavelet Texture Analysis
14. Correction for shadow bias Object of given height, shadow lengthening goes with with grazing angle Buscombe et al., Journal of Hydraulic Engineering, in review
15. Texture Lengthscale Mean texture lengthscale (m) w = (s σ2(s) δs) cos(θ) Scale (m) Normalized variance spectrum Grazing angle Buscombe et al., Journal of Hydraulic Engineering, in review
16. Wavelet Texture Analysis
17. Colorado River in Glen Canyon
18. Colorado River in Marble Canyon at RM 30
19. Colorado River in Marble Canyon at RM 30
20. Colorado River in Marble Canyon at RM 61
21. Colorado River in Marble Canyon at RM 61
22. Summary Low-cost, low-profile, and highly portable sidescan sonar for imaging shallow riverine benthic sediments. A new automated, spatially explicit and physically based method for texture lengthscales in sidescan echograms Not a direct measure of grain size could provide a basis for objective, automated riverbed sediment classification
23. Summary Low-cost, low-profile, and highly portable sidescan sonar for imaging shallow riverine benthic sediments. A new automated, spatially explicit and physically based method for texture lengthscales in sidescan echograms Not a direct measure of grain size could provide a basis for objective, automated riverbed sediment classification
24. Summary Low-cost, low-profile, and highly portable sidescan sonar for imaging shallow riverine benthic sediments. A new automated, spatially explicit and physically based method for texture lengthscales in sidescan echograms Not a direct measure of grain size could provide a basis for objective, automated riverbed sediment classification
25. Summary Low-cost, low-profile, and highly portable sidescan sonar for imaging shallow riverine benthic sediments. A new automated, spatially explicit and physically based method for texture lengthscales in sidescan echograms Not a direct measure of grain size could provide a basis for objective, automated riverbed sediment classification
26. Thanks for listening Buscombe et al., Automated riverbed sediment classification using low-cost sidescan sonar. Journal of Hydraulic Engineering, in review dbuscombe@usgs.gov
27. This slide is intentionally blank.
28. Texture Lengthscale Autospectral variance (function of scale, s) σ2(s) = (n - ( nW 2 n (s) δy))2 W 2 n (s)δy Location along scan (pixel) Wavelet power spectrum (function of location and scale) Metres between pixels Buscombe et al., Journal of Hydraulic Engineering, in review
29. Bed picking
30. Shadow removal