Use of the Sentinel-2 and Landsat-8 Satellites for Water Quality Monitoring: An Early Warning Tool in the Mar Menor Coastal Lagoon

Abstract

During recent years, several eutrophication processes and subsequent environmental crises have occurred in Mar Menor, the largest hypersaline coastal lagoon in the Western Mediterranean Sea. In this study, the Landsat-8 and Sentinel-2 satellites are jointly used to examine the evolution of the main water quality descriptors during the latest ecological crisis in 2021, resulting in an important loss of benthic vegetation and unusual mortality events affecting different aquatic species. Several field campaigns were carried out in March, July, August, and November 2021 to measure water quality variables over 10 control points. The validation of satellite biogeochemical variables against on-site measurements indicates precise results of the water quality algorithms with median errors of 0.41 mg/m3 and 2.04 FNU for chlorophyll-a and turbidity, respectively. The satellite preprocessing scheme shows consistent performance for both satellites; therefore, using them in tandem can improve mapping strategies. The findings demonstrate the suitability of the methodology to capture the spatiotemporal distribution of turbidity and chlorophyll-a concentration at 10–30 m spatial resolution on a systematic basis and in a cost-effective way. The multitemporal products allow the identification of the main critical areas close to the mouth of the Albujon watercourse and the beginning of the eutrophication process with chlorophyll-a concentration above 3 mg/m3. These innovative tools can support decision makers in improving current monitoring strategies as early warning systems for timely assistance during these ecological disasters, thus preventing detrimental conditions in the lagoon.

Fertilization strategies for abating N pollution at the scale of a highly vulnerable and diverse semi-arid agricultural region (Murcia, Spain)

“…N surplus is calculated as the difference between total N inputs and output. Figures 3(d) and (f) show considerable areas with total N inputs and N surplus >200 kg N ha −1 , which correspond to irrigated horticultural crops and citrus (see the supplementary information and figures S1 & S2) and are in the central-eastern and southeastern areas of the region, especially in the surroundings of the Mar Menor lagoon, which is consistent with the severe and recurring impacts already reported in the area (Caballero et al 2022).…”

Synergistic Use of Earth Observation Driven Techniques to Support the Implementation of Water Framework Directive in Europe: A Review

“…The analysis reveals that the difference in the algae area increases with the time difference between the same-day overpass. Cabarello et al (2022) [62] examined the evolution of the key indicators of water quality during the most recent ecological crisis in 2021, which resulted in a significant loss of benthic vegetation and strange death rate events affecting various aquatic species.…”

“…The analysis reveals that the difference in the algae area increases with the time difference between the same-day overpass. Cabarello et al (2022)[62] examined the evolution of the key indicators of water quality during the most recent ecological crisis in 2021, which resulted in a significant loss of benthic vegetation and strange death rate events affecting various aquatic species.Based on our analysis, a significant but smaller number of studies explore coarser resolution (>250 m) sensors such as MODIS (Moderate Resolution Imaging Spectroradiometer) (13%)[5,52,55,[63][64][65][66][67] and MERIS (MEdium Resolution Imaging Spectrometer) (8.6%)[4,52,53,[68][69][70]. For example, Zheng and DiGiacomo (2017)[52] collected match ups for four sensors including the SeaWiFS, the MODIS onboard Aqua, the MERIS, and VIIRS to develop a new Chl-a model based on the semi-analytical approach, in a coastal zone…”

Deep-Learning-Based Retrieval of an Orange Band Sensitive to Cyanobacteria for Landsat-8/9 and Sentinel-2

“…EMOTE sensing of water quality in inland and nearshore coastal waters has undergone significant progress over the last decade with the launch of Landsat-8/9 and Sentinel-2 satellites [1], [2]. Operational Land Imager (OLI) and Multispectral Imager (MSI) sensors aboard Landsat-8/9 and Sentinel-2, respectively, are not originally designed for aquatic applications.…”