Assessment of Sentinel-2 and Landsat-8 OLI for Small-Scale Inland Water Quality Modeling and Monitoring Based on Handheld Hyperspectral Ground Truthing

Abstract

This study investigates the best available methods for remote monitoring inland small-scale waterbodies, using remote sensing data from both Landsat-8 and Sentinel-2 satellites, utilizing a handheld hyperspectral device for ground truthing. Monitoring was conducted to evaluate water quality indicators: chlorophyll-a (Chl-a), colored dissolved organic matter (CDOM), and turbidity. Ground truthing was performed to select the most suitable atmospheric correction technique (ACT). Several ACT have been tested: dark spectrum fitting (DSF), dark object subtraction (DOS), atmospheric and topographic correction (ATCOR), and exponential extrapolation (EXP). Classical sampling was conducted first; then, the resulting concentrations were compared to those obtained using remote sensing analysis by the above-mentioned ACT. This research revealed that DOS and DSF achieved the best performance (an advantage ranging between 29% and 47%). Further, we demonstrated the appropriateness of the use of Sentinel-2 red and vegetation red edge reciprocal bands 1 / B 4 × B 6 for estimating Chl-a ( R 2 = 0.82 , RMSE = 14.52 mg / m 3 ). As for Landsat-8, red to near-infrared ratio ( B 4 / B 5 ) produced the best performing model ( R 2 = 0.71 , RMSE = 39.88 mg / m 3 ), but it did not perform as well as Sentinel-2. Regarding turbidity, the best model ( R 2 = 0.85 , RMSE = 0.87 NTU) obtained by Sentinel-2 utilized a single band (B4), while the best model (with R 2 = 0.64 , RMSE = 0.90 NTU) using Landsat-8 was performed by applying two bands ( B 1 / B 3 ). Mapping the water quality parameters using the best performance biooptical model showed the significant effect of the adjacent land on the boundary pixels compared to pixels of deeper water.

Measurement of Total Dissolved Solids and Total Suspended Solids in Water Systems: A Review of the Issues, Conventional, and Remote Sensing Techniques

“…RS sensors offer a variety of spatial, spectral, and temporal resolutions. One example is contrasting the temporal resolutions of Landsat 8 OLI and Sentinel-2 A/B MSI, both of which have revisit times of 16 days and 5 days, respectively [2,268].…”

Spatiotemporal Variations in Biophysical Water Quality Parameters: An Integrated In Situ and Remote Sensing Analysis of an Urban Lake in Chile

“…Low-to-medium-resolution satellites have been widely used to develop eutrophic inland water classification algorithms and to retrieve the Chl-a concentration [45]. In terms of optics, Chl-a exhibits two points of highest reflectance, located in the green and near-infrared wavelength ranges at 550 nm and 700 nm, respectively [3]. A total of three spectral indices (Table 4) have been previously used to detect the presence of Chl-a in water by remote sensing.…”

“…These lakes represent intricate systems that ensure the continued provision of a range of ecosystem services that demand integrated actions within the surrounding watershed or directly within the lake itself [1,2], especially in urban lake environments. Ensuring the quality of surface and groundwater is an essential duty carried out by organizations responsible for water supply and management [3]. It is crucial to implement appropriate conservation and management measures, both conducing to improve the water quality of a lake, thus safeguarding their long-term ecological and socioeconomic value [4] by analyzing the trophic state of a lake.…”

Comparative Evaluation of Semi-Empirical Approaches to Retrieve Satellite-Derived Chlorophyll-a Concentrations from Nearshore and Offshore Waters of a Large Lake (Lake Ontario)

“…Also of note, ACOLITE includes two correction methods: Dark Spectrum Fitting (DSF, the processor's default) and Exponential Extrapolation (EXP). Because DSF has been reported as the better choice for aquatic studies [18,23], it was used in this study. Table S2 in Supplementary Materials summarizes the atmospheric correction methods utilized in this study.…”