REMOTE SENSING OF WATER QUALITY IN THE TENNESSEE RIVER USING SENTINEL-2 IMAGERY

The optical properties (i.e. reflectance) of water depend on the concentration and characteristics of suspended sediments, phytoplankton (chlorophyll-a), and dissolved organic matter. Sensors on earth observation satellites can quantify the amount of solar radiation at various wavelengths reflected by surface water, which can be correlated to different water quality parameters. This provides an alternative method of estimating water quality with three significant advantages over ground sampling. Firstly, the near-continuous spatial coverage of satellite imagery allows for synoptic estimates of water quality over large areas. Secondly, the global/regional coverage of satellites allows for the estimation of water quality in remote and inaccessible areas. Thirdly, the relatively long record of archived imagery allows estimation of historical water quality, when no ground measurements can possibly be acquired.

Currently, no remote sensing-based algorithm is available to study surface water quality in the Tennessee River. This study explores the potential of the Sentinel-2 satellite for estimating Turbidity, Chlorophyll-a, Conductivity, pH, and Dissolved Oxygen (DO) in the Tennessee River using recently acquired satellite imagery and concurrently obtained in situ measurements of corresponding water quality data. The Copernicus Sentinel-2 mission comprises a constellation of two polar-orbiting and sun-synchronous satellites. It acquires multispectral imagery in visible and near-infrared (VNIR) and shortwave infrared (SWIR) at variable spatial resolutions (10 m, 20 m, and 60 m) every 10 days globally. This paper presents the preliminary results of this research.