Airborne hyperspectral remote sensing to assess spatial distribution of water quality characteristics in large rivers: The Mississippi River and its tributaries in Minnesota

Leif Olmanson, Patrick L. Brezonik, Marvin E Bauer

Research output: Contribution to journalArticlepeer-review

188 Scopus citations

Abstract

Aircraft-mounted hyperspectral spectrometers were used to collect imagery with high spatial and spectral resolution for use in measuring optically active water quality characteristics of major rivers of Minnesota. Ground-based sampling undertaken concurrent with image acquisition provided calibration data for chlorophyll, suspended solids, turbidity and other measures of water clarity. Our approach identified the spectral characteristics that distinguish waters dominated by several inherent optical properties (IOPs), and we used those characteristics to develop models to map water quality characteristics in optically complex waters. For phytoplankton related variables (volatile suspended solids (VSS) and chlorophyll a (chl a)), the ratios of the scattering peak at the red edge (~700nm) with the reflectance troughs caused by chlorophyll absorption at ~670nm and other plant pigment absorption peaks at 592 and 620nm all were strong predictors of chl a and VSS (r2 values of 0.73-0.94). The scattering peak at ~700nm was a strong predictor of variables related to water clarity (total suspended solids (TSS), turbidity and turbidity tube (T-tube)) (r2 values of 0.77-0.93). For mineral-based variables (nonvolatile suspended solids (NVSS) and the ratio NVSS:TSS), combinations of the TSS and chl a relationships described above were strong predictors (r2 values of 0.73-0.97) and the most robust because this model corrects for the scattering of phytoplankton at ~700nm. Application of the methods to quantify spatial variations in water quality for stretches of the Mississippi River and its tributaries indicate that hyperspectral imagery can be used to distinguish and map key variables under complex IOP conditions, particularly to separate and map inorganic suspended sediments independently of chlorophyll levels.

Original languageEnglish (US)
Pages (from-to)254-265
Number of pages12
JournalRemote Sensing of Environment
Volume130
DOIs
StatePublished - Mar 5 2013

Bibliographical note

Funding Information:
Support for data acquisition, processing and analysis was provided by funding from the Legislative-Citizen Commission on Minnesota Resources (LCCMR) Environment and Natural Resources Trust Fund to the Minnesota Pollution Control Agency and the University of Minnesota Agricultural Experiment Station. For assistance with field data coordination, collection and sample analysis, special thanks go to Bruce Wilson (Minnesota Pollution Control Agency), Steve Kloiber (Metropolitan Council), and Kent Johnson (Metropolitan Council) and sampling crews from the Minnesota Pollution Control Agency, Metropolitan Council, Minnesota Department of Natural Resources, and Minnesota Department of Agriculture, which were dispatched on short notice to collect water samples. Weather forecasts from KARE 11 meteorologist Jonathan Yuhas were invaluable in planning for data acquisitions under clear conditions.

Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.

Keywords

  • Airborne
  • CDOM
  • Chlorophyll
  • Hyperspectral imagery
  • Imaging spectroscopy
  • Inherent optical properties
  • Mineral suspended sediment
  • Mississippi River
  • Remote sensing
  • River
  • Turbidity
  • Water quality

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