TITLE:
Estimation of Chlorophyll and Turbidity Using Sentinel 2A and EO1 Data in Kneiss Archipelago Gulf of Gabes, Tunisia
AUTHORS:
Rim Katlane, Cécile Dupouy, Boubaker El Kilani, Jean Claude Berges
KEYWORDS:
Hyperspectral, Kneiss Islands, Multispectral, Shallow Waters, Water Quality
JOURNAL NAME:
International Journal of Geosciences,
Vol.11 No.10,
October
30,
2020
ABSTRACT: Multispectral and hyperspectral
sensor data of the bio-optical parameters with a high spatial resolution are
important for monitoring and mapping of the coastal ecosystems and estuarine
areas, such as the Kneiss Islands in the Gulf of Gabes. Sentinel 2 S2A and
Hyperion Earth observing-1 (EO1) imaging sensors reflectance data have been
used for water quality determination and mapping of turbidity TU and
chlorophyll Chl-a in shallow waters. First, we applied a tidal swing area mask
based on uncorrelated pixel via 2D scatter plot between 665 nm and 865 nm to
eliminate the overestimation of the concentration of water quality parameters
due to the effect of the bottom reflection. The processing for mapping and validating
Chl-a, Turbidity S2A, and EO1 were performed using a relation between
reflectance bands and in situ measurements. Therefore, we were able to validate
the performance of the case 2 regional coast colour processor (C2RCC) as well
as our region-adapted empirical optical remote sensing algorithms. Turbidity
was mapped based on the reflectance of 550 nm band for EO1 (R2 =
0.63) and 665 nm band for S2A (R2 = 0.70). Chlorophyll was mapped
based on (457/528 nm) reflectance ratio (R2 = 0.57) for EO1 and
(705/665 nm) reflectance ratio (R2 = 0.72) for the S2A.