Assessment of Coastal Water Quality by Testing a Linear Model Using Landsat 8 sst Data: Exploratory Study

Abstract

The Mediterranean Basin, off the coast of Tangier, Morocco, is one of the most valuable seas be-cause of the diversity of its ecosystem. However, pollution has become a growing issue along this coast recently. For this reason, we tested a linear model developed for the Atlantic western coastal waters of Tangier using sea surface temperature (SST) estimated from Landsat 8 images and Escherichia coli concentration (E. coli) in-situ measurement to determine the Mediterranean northern coastal waters quality of Tangier in fifteen Selected Sites (SS1 to SS15) along the coast from Tangier to Ksar-Sghir. In addition, descriptive statistics, and geographic information systems (GIS) were employed to explore the spatial association of the data. The results indicate that the SST and E. coli distributions have the highest values in the SS4-SS13 and SS15 due to the Souani, Mghogha rivers and Tangier Med Port, reflecting poor quality and a very high level of dangerous contamination in this area. The SS1, SS2, SS3, and SS14 reflected low levels of SSTs and E. coli concentrations thus, medium, and good-quality water around the cities of Tangier and Ksar-Sghir. The relationship be-tween water temperature and E. coli concentration showed a high correlation coefficient; 80% (RMSE = 0.8) and the IDW, helped frame the pollution zone along the shore. Although only values near the shore are valid, while the values deeper in the Gibraltar Strait were extrapolated due to the absence of data points at depth. This IDW results showed the negative impact of estuaries dis-charges and maritime traffic. As a result, the tested model is useful for estimating the quality of coastal water on the Mediterranean side of Tangier, and in the future potentially monitoring pollution in this region.