Field testing two instruments for remotely sensing water quality in the Tennessee Valley

Two airborne remote sensing systems, the Compact Airborne Spectrographic Imager (CASI) and the Airborne Multispectral Measurement System (AMMS), were field tested over reservoirs in the Tennessee River Valley during the summer of 1991 and the winter (AMMS only) of 1992. Univariate, linear regression analyses using ratioed wavelength bands and line height algorithms for radiance (CASI) or reflectance (AMMS) in the 625-725-nm wavelength range provided the best correlations to groundtruthed uncorrected chlorophyll a (R super(2) = 0.84-0.95) for both imaging systems during the summer when phytoplankton dominated the suspended solids composition. For the winter flight, using the AMMS system 3-4 days after a major rain event, reflectance in the 690-710-nm range was correlated to turbidity and suspended solids concentrations (R super(2) = 0.79-0.85). The high correlations between imaged data and chlorophyll in July-August and inorganic turbidity in February-March demonstrate the feasibility of using low-cost imaging spectrometers and multispectral video cameras from fixed-wing aircraft.