Bathymetric Modeling from Satellite Imagery via Single Band Algorithm (SBA) and Principal Components Analysis (PCA) in Southern Caspian Sea

Document Type: Original Research Paper

Authors

1 Department of Environment, Faculty of Natural Resources, Tarbiat Modares University, Noor, Mazandaran, Iran

2 Faculty of Geodesy and Geomatics Eng., K. N. Toosi University of Technology, Tehran, Iran

3 Faculty of Geo-Information Science and Earth Observation (ITC), Enschede, The Netherlands

Abstract

Remotely sensed imagery is proving to be a useful tool to estimate water depths in coastal
zones. Bathymetric algorithms attempt to isolate water attenuation and hence depth from other factors by
using different combinations of spectral bands. In this research, images of absolute bathymetry using two
different but related methods in a region in the southern Caspian Sea coasts has been produced. The first
method used a Single Band Algorithm (SBA) and assumed a constant water attenuation coefficient throughout the blue band. The second method used Principal Components Analysis (PCA) to adjust for varying water attenuation coefficients without additional ground truth data. PCA method (r=-0.672394) appears to match our control points slightly better than single band algorithm (r=-0.645404). It is clear that both methods can be used as rough estimates of bathymetry for many coastal zone studies in the southern Caspian Sea such as near shore fisheries, coastal erosion, water quality, recreation siting and so forth. The presented methodology can be considered as the first step toward mapping bathymetry in the southern Caspian Sea. Further research must investigate the determination of the nonlinear optimization techniques as well as the assessment of these models’ performance in the study area.

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