Estimating Chlorophyll-A Concentration in a Freshwater Lake Using Landsat 8 Imagery

Abstract

Numerous studies suggest that chlorophyll-a in waters can be measured using Landsat TM/ETM imagery but the feasibility of newly launched Landsat 8 with Operational Land Imager (OLI) on board is still being tested. Jordan Lake is one of the most eutrophic reservoirs in North Carolina, U.S and there is a great need to monitor the spatial distribution of chlorophyll-a in this freshwater lake for better water quality management. The purpose of this study was to examine the applicability of using Landsat 8 imagery to estimate and map chlorophyll-a concentration in Jordan Lake. In this study, the relationship between the reflectance value of an individual OLI band and in situ chlorophyll-a concentration was examined to identify bands sensitive to chlorophyll-a. We also investigated the performance of ratio-based spectral indices to retrieve chlorophyll-a concentrations in Jordan Lake. Two optimal linear equations were developed to model the relationship between ratio-based spectral index and in situ chlorophyll-a concentration in Jordan Lake for different seasons. There was a significant correlation between the spectral index derived from Landsat 8 imagery and chlorophyll-a concentration for Jordan Lake in summer and fall 2013. Spatial distribution of chlorophyll-a concentration in the Jordan Lake was successfully mapped using Landsat 8 imagery for two seasons in 2013. Despite the limitation of this work, our findings suggest that Landsat 8 imagery can be used to estimate chlorophyll-a concentration in fresh waters and it is promising to estimate and map chlorophyll-a concentration in freshwater lakes.

Keywords: Chlorophyll-a, Spectral index