Application of Landsat 8 OLI for monitoring the coastal waters of the US Virgin Islands

Abstract

ABSTRACT Previous studies in the US Virgin Islands (USVI) have shown that land-based sources of pollution associated with watershed development coupled with climate is causing coral reef degradation. A good indicator that can be used to assess stress on these environments is the water quality. Conventional assessment methods based on in-situ measurements are timely and costly. Satellite remote sensing techniques offer better spatial coverage and temporal resolution to accurately characterize the dynamic nature of Water Quality Parameters (WQPs, chlorophyll-a), total suspended sediments (TSM), and coloured-dissolved organic matter). However, the interference of multiple optically active WQPs that characterize the water column as well as reflectance from the bottom substrates poses a challenge especially in shallow coastal environments such as the USVI. The optical properties of USVI waters are a function of multiple WQPs with chlorophyll-a values ranging from 0.10 to 2.35 μg L−1 and TSM values from 8.97 to 15.7 mg L−1. In this study, field data were combined with NASA’s Landsat Operational Land Imager (OLI) sensor data to specifically model chlorophyll-a variability in the USVI waters based on spectral indices approach. Landsat OLI spectral-based model produced promising results for characterizing the variability of chlorophyll-a in the USVI (coefficient of determination (R 2) = 0.70; root-mean-square error (RMSE) = 0.042 μg L−1). Model developed in this study will significantly improve near-real time and long-term water quality monitoring in USVI and this will potentially help to provide insight to factors contributing to coral reef decline.