IMPACT OF URBANIZATION ON THE DUNE ECOSYSTEM: CASE OF THE CITY OF ‎ECHATT AND SIDI MBAREK (EL TARF)‎

Context and backgroundThroughout history, the severity of coastal impacts has varied depending on social and environmental factors. Human activities in general have caused large-scale environmental and morphological changes, and our study area is not outside this context.Goal and Objectives:This study aims to reveal the evolution of urban fabric of the city of Echatt and sidimbarek and their degree of influence on the state of dune cordon last 37 years.Methodology:The methodology followed during this study is based on satellite and topographic data as well as on measurements and observations made in the field. In order to study the evolution of urban fabric of the study area.The approach adopted is based on a study of several satellite images and google Earth pro images at different dates in order to determine the extent of changes that occurred between 1984 and 2021.Results:The results show an increase in coastal urbanization at varying rates amounting to 11.92 ha/year between (1984-2000), 4.95 ha/year between (2000; 2010) and 9. 92 ha/year between (2010,2021); and landscape changes that have developed at different rates over time due to the exploitation of the dune cordon of the city of echatt and sidimbarek in an irrational way that can lead to a total removal of vegetation cover, because according to the results obtained, more than half of the vegetation cover of the coastal dunes has been removed in 37 years Thematic maps and results obtained at different periods show that the forest landscape has gradually converted into dry land despite the entry into force of the Algerian Coastal Law 02-02 on the protection and enhancement of the coast, which aimed at the protection of the coast and sustainable use of its resources.

Seasonal variation of microplastics density in Algerian surface waters (South-Western Mediterranean Sea)

Coastal waters worldwide are widely contaminated with various-size plastics, whose presence in aquatic ecosystems has been shown to produce a wide range of economic and social impacts and harmful effects on marine ecosystems. While microplastics have been reported from many regions of the Mediterranean Sea, very few data exist regarding microplastics concentration inn Algerian waters. In this study, we used a Manta trawl (330 μm) at six sampling stations in Bou-Ismail Bay, Algeria (South-West Mediterranean Sea) in order to provide novel information about the occurrence and composition of microplastics along the Algerian coast. Sampling was performed seasonally at six different sampling stations in 2018, providing additional information about the spatio-temporal variability of microplastics concentrations at the sea surface. Microplastics were found in all collected samples, with highly variable concentrations of 0.95, 0.88, 1.26, and 0.36 items/m3 in Autumn, Winter, Spring and Summer, respectively, and an overall mean concentration of 0.86 ± 0.35 items/m3. A classification based on the shape and appearance of microplastics indicated the predominance of fibers (32%), followed by fragments (27%), films (16%), foams (13%), and granules (12%). A qualitative microplastics analysis through Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) revealed that microplastics were mainly composed of polyethylene (68.2%), polypropylene (24.7%), polystyrene (4.1%) and other polymers (3%). These data provide an initial overview of the quantity, characteristics, and spatio-temporal distribution of floating microplastics in Bou-Ismail Bay (Algeria)

Monitoring of Marine Pollution

Many of the pollutants discharged into the sea are directly or indirectly the result of human activities. Some of these substances are biodegradable, while others are not. This study is devoted to monitoring areas of the environment. Methods assessment is based on monitoring data and an evaluation of the impact of pollution.Surveillance provides a scientific basis for standards development and application. The methodology of marine pollution control is governed by algorithms and models. A monitoring strategy should be put in place, coupled with an environmental assessment concept, through targeted research activities in areas identified at local and regional levels. This concept will make it possible to diagnose the state of ""health"" of these zones and consequently to correct any anomalies. Monitoring of the marine and coastal environment is based on recent methods and validated after experiments in the field of marine pollution

Modelling and mapping of the pollution marinates and of the bathymetry from the satellite imaging

Le contrôle de la qualité de l'eau est fondé naturellement et traditionnellement sur des mesures et des prélèvements in situ. Des images satellites étalonnées à partir des données mesurées in situ fournissent une information quantitative et continue sur le milieu aquatique et peuvent être employées pour estimer, avec une approximation raisonnable, les facteurs affectant la qualité de l’eau L’objectif de ce travail consiste à modéliser les propriétés optiques de l’eau de mer et les paramètres physico-chimiques qui caractérisent les eaux côtières. L'application est basée sur le développement d’un Système d’Information Marin caractérisant un système de gestion de base de données géoréférencié POlGIS dédié à la gestion de l'information marine dans le cas de contrôle, suivi et surveillance de la pollution. Nous présentons des modèles exprimant les variables indicatrices de la qualité des eaux du littoral Algérois et la réflectance calculée de chaque pixel à partir d’un modèle physique de correction radiométrique. Les mesures in- situ sont effectuées pour des zones de différentes qualités d’eaux et leurs réflectances sont calculées à partir des images satellites SPOT, Landsat TM, MSS, IRS1C et Seawifs Finalement, des modèles sont établies avec les réflectances permettent d’obtenir des images satellites indicatrices de la pollution et de la bathymétrie des zones côtières à partir du logiciel de traitement d’image PCSATWIN développé afin d’estimer pour chaque pixel le degré de pollution du milieu.In order to protect the natural medium and to control the pollution caused by such rejects, it is necessary to achieve a continuous survey of the reject zones. The goal of this study is a developed a methodology for modelling pollution and bathymetry from the digital satellite images.Indeed, our objective consists of the development of a software POLGIS intended for the management of the marine databases for the control and the monitoring of the pollution Satellite imagery can be used to estimate, with a reasonable accuracy, the factors affecting the water quality .It has a great importance to achieve the necessary continuous monitoring of the relevant area with an overall analysis of its pollution. A modelling analysis between the pollution contents and the reflectance calculated by the satellite images allow us to transform rough images into images treated and combined using a software of satellite image processing PCSATWIN developed in this study. This complex phenomena us developed an analytic model of radiatif transfer simulation in water coupled to an atmospheric model in order to simulate measure by satellite. This direct model permits to follow the solar radiance in his trajectory Sun-Atmosphere - Sea - Depth of sea- sensor. The goal of this simulation is to show for every satellite of observation (Spot, Landsat MSS, TM) possibilities that can offer in domain of bathymetry.The reflectance coefficient is calculated from satellite image, the detection and the possible determination of the zones contaminated by pollution using the space techniques constitute an effective means to intervene in order to ensure the monitoring of the Algerian coasts. The analysis shows us that each sensor offers useful information and that the combination between these various informations makes it possible to propose a procedure of maps establishment that can be interpreted as pollution maps

Chlorophyll Estimation from Fluorescence Vertical Profiles in Ocean

The present study deals with the correction of chlorophyll-a (Chl-a) estimated from fluorescence data, the proposed method test for the first time a ratio between Chl-a from high-performance liquid chromatography (HPLC) measurements and its corresponding fluorescence. Considering the variability of this ratio with depth, the adjustment of fluorescence data was greatly improved. This ratio increase in the oceanic surface layer probably because of the quenching effect, however, it decreases and becomes stable with depth. This approach can be used to correct fluorescence values for future large datasets of biological variables. Finally, this method is designed for a global scale and/or regional applications

Combination of Satellite Images and Numerical Model for the State Followed the Coast of the Bay of Bejaia-Jijel

Bay of Bejaia-Jijel extends over a length of 100 km with the presence of the ports, the beaches of rivers that discharge of the bay. This area characterized by strong economic activity, namely tourism and fisheries. However, severe erosion, high hydrodynamic activity and significant silting of ports affect this bay. Hence, the interest of this study, which tries to explain these phenomena, based on multisource data with multitasking models. First, we developed an algorithm that can convert satellite images in coastline vector. This technique applied to three images LANDSAT TM and OLI sensed in 1987, 2011; 2015. The multi-temporal monitoring coastlines show that the region suffered severe erosion. This erosion is 4.6 m / year for the period of 1987/2011 and 1.5 m / year for the period 2011/2015. To explain this phenomenon we interested to do a study of hydrodynamics using the SWAN software. We used a long time series of wind speed and direction to discern extreme cases in the region. For maximum wind, the significant wave height recorded very high values and a very active orbital current with a speed that exceeds 0.7 m / s. Numerical modelling has allowed us to explain the erosion but does not explain the speed difference coastline. To find the explanation of erosion speed difference between the two periods we consulted the administrative archive of the region. In the archive, the number of authorized hourglasses is, 12 in the 90s, but 36 quarries operate haphazardly. In this period the balance of suspended matter is completely unbalanced which promotes erosion. After 2008, these quarries were closed therefore the balance of the suspended material has improved and consequently coastal erosion has decreased

Protection and enhancement of the coastal area of the wilaya of El Tarf (Algeria): Automatic analysis using computer tools

The coastline of El Tarf province, stretching for 90 km, presents a great variety of forms and complex ecosystems that need to be protected. The Coastal Law 02-02 was established to achieve this goal by using geographic information system (GIS) and remote sensing to assess the degree of implementation of this law on the ground. This evaluation highlighted a significant evolution of land use in the coastal zone of El Tarf province over a period of 32 years, from 1990 to 2022. In 1990, the area was predominantly forested (55.08%) with a proportion of agricultural land of 27.26% and a significant portion of wetland areas (17.26%). Over time, the forested area decreased to reach 48.58% in 2022, while agricultural land and urban areas increased. This evolution suggests increasing pressure on natural resources, with potential implications for the environment and biodiversity of the region. Despite the 2002 Coastal Law 02-02s which sets specific provisions for the protection and enhancement of the coastline, it is important to emphasize the importance of sustainable management of natural resources and land use in the region. It is essential to implement measures to protect the fragile ecosystems of the region and ensure the sustainability of natural resource use to preserve the environment and biodiversity of the region for future generations. This analysis could also eventually enable decision-makers to have supporting elements to evolve the law 02.02 with the aim of better preserving the coastal area