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The Suez Canal is a major bottleneck of global shipping. The stranding of the Ever Given, one of the world's largest container ships, in early 2021 showed how much global supply chains depend on the Suez Canal. The canal navigability directly depends on the incoming fluxes of sediments, either through the entrance on the Mediterranean Sea or from smaller tributaries along the canal. Here we model the hydrodynamics of the southeastern Mediterranean Sea, Suez canal and northern Gulf of Suez with the multi-scale ocean model SLIM (www.slim-ocean.be). The model can locally achieve a resolution of about 50 m and hence explicitly describes the flow through the narrow branches of the canal. The hydrodynamic model is then used to drive a sediment transport model that represents the dynamics of several types of sediments originating from the Nile delta, from shorelines along the Mediterranean Sea, and from inland channels connecting the Nile to the Suez Canal. Model results allow us to estimate the sediment deposition rate within the canal under present and future climate, and for different land and river management scenarios. The latter include the impact of existing and future dams along the Nile River and irrigation practices within the Nile Delta. Our result suggest that the Nile River management directly impacts the Suez canal navigability. This interconnection between the Nile River and the Suez Canal calls for an integrative management strategy.

Ecological study of Mediterranean wetland: Sediment dynamics and blue carbon storage Aya Hammami1, Kerim Ben mustapha1, Oula Amrouni 1, Amjad Kallel2 1 University of Carthage, National Institute of Marine Sciences and Technologies, LR16INSTM04,2025, Tunis, Tunisia2 University of Sfax, National School of Engineering, 3038 Sfax, Tunisia AbstractThe aim of this study is to monitor the sediment dynamic and to estimate the percentage of carbon sequestered by macrophytes in the coastal lagoon of Ghar El Melh, Gulf of Tunis Mediterranean. A total of 21 surface sediment samples were collected during the winter campaign, completed by a second floristic campaign in April 2021 for the identification of the spatial distribution of the phanerogam Posidonia oceanica. The results showed that the lagoon is characterized by two types of sedimentary facies: dominant silty facies (65%) with an average size D50 which varies from 4.3 µm to 8.7 µm and sandy facies (35%) with an Mz grain sized ranges from 2Φ to 3Φ. The mineralogical identification of the lagoon sediments shows the presence of a biogenic calcium carbonate (CaCO3) :4% to 100%. The rate of organic matter OM: 2% to 11%. Sedimentological and mineralogical analysis of the coastal lagoon shows the coupled origin of sediment supplies. At the level of the banks of the lagoon, the silty facies enriched in carbonated fraction are allochthonous via the fluvial yields of the lower valley of Medjerda. The muddy deposits in the center of the OM-enriched lagoon are formed by the phytoplanktonic primary production of zooplankton, indicative of bacterial activity in the water column. Floristic investigation of the coastal lagoon reveals the presence of the Posidonia oceanica species in sandy areas. The average carbon capture rate of Posidonia in the lagoon is estimated to be ~15.6 t/ha. Nevertheless, Posidonia meadows are absent in central areas and adjacent to urban areas, characterized by muddy facies with a relatively high level of organic matter. Key words: Ghar El Melh lagoon, phanerogams, blue carbon, Mediterranean, Ecohydrology.

Coastal wetland ecosystems are complex environments subject to physical factors and multiple yield supplies. The climate change impacts are strongly visible in those low-lying areas, in close relationships with the decrease of the continental water and sediment supply, marine storms and submersion. To understand the interactions between the coastal components we adopt the ecohydrology approach for a lagoon ecosystem in North Africa. The ecohydrology approach is based on as a compeling of well-experimented data as the sediment dynamics, the hydrology of the watershed basin and the coastal aquifer, and the biodiversity and the remote sensing observations in relation with the socioeconomic activities. The ecohydrology concept is focused in our research on the coastal ‘hot spot’ areas on the deltaic-lagoon and sandy barrier areas identified as very highly vulnerable to the sea level rise and marine disasters. The main goal is to establish a shared database and an innovative Nature Based Solution with the regional communities to enhance the coastal resilience and to better explore the aquatic resource for a sustainable blue economy, in the context of rapid environmental changes in the Mediterranean arid-regions, driven by both climate change and anthropogenic negative impacts on natural landscapes.

IntroductionSoil erosion, sediment loss, and catchment degradation are typical of the combined effects of sea level rise and climate change at the coastline and further inland. We describe an integrated, multidisciplinary, nature-based solutions (NBSs) approach to resolving some of the most pressing issues facing coastal communities affected by hydrological impacts due to increasing water levels and saline intrusion. Our blue and green infrastructure solutions are developed for coastal Africa and are equally applicable and scalable to coastlines and hydrological systems around the world where sediment starvation, changing rainfall patterns, and saline intrusion of the coastal aquifer are causing major changes to natural ecosystems, human habitats, and agriculture.MethodsWe use a systems approach that combines modeling and data collection to examine the complete system, from upstream riverine inputs and reservoirs to coastal wetlands, the littoral system, and the coastal aquifer. We emphasize the requirement to understand the interactions between existing natural and artificial assets as a precursor to recommending any management changes to the natural or anthropogenic infrastructure systems in place. A combination of NBSs and novel management techniques are proposed to restore natural sediment and freshwater supplies to coastal communities. We introduce two new green infrastructure types, which have been extensively tested and have the potential to significantly reduce erosion while simultaneously providing desalinated water (and electricity) to nearby coastal communities. We hypothesize that it is possible to reduce the extent of land degradation caused by saline intrusion through better management of water abstraction in the coastal aquifer. ResultsWe expect our approach to deliver significant environmental and socio-economic co-benefits to coastal and inland communities and ecosystems, many of which are already suffering from the effects of land degradation and a lack of investment. When our NBSs are combined, their synergy greatly increases benefits on a regional scale.

Port areas are coastal socio-ecosystems, located at the land-sea interface, subject to both autochthonous sources of pollution and receiving terrigenous inputs from watersheds. This project focuses on the study of the problem of dredging operations in port areas on both shores of the Mediterranean: in the north the ports of the Gulf of Aigues Mortes (France) and in the south the port of Ghar el Melah (Tunisia). The study focuses on monitoring the resuspension of chemical and microbiological contaminants during these operations. The initial state of water and sediment quality before the dredging operations is underway in the port of Carnon and a sampling campaign is planned for June 2022 in the port of Ghar el Melah. Monitoring of the remittance will be implemented in the fall, which will allow the port management to take management measures and reduce these contaminations if necessary. A focus will be made on the comparison of the management of these dredging operations on the two shores of the Mediterranean and the potential to reuse these sediments for beach nourishment in erosion. Finally, perception surveys among the actors and users of the ports on the risk of marine submersion, on the perception of the degradation of the quality of the environment, on the dredging operations and the reuse of the dredged sediments, on the uses are underway on the different sites in France and Tunisia., Les zones portuaires constituent des socio-écosystèmes littoraux, situés à l’interface Terre-Mer soumis à la fois à des sources de pollutions autochtones et recevant les apports terrigènes provenant des bassins versants. Ce projet porte sur l’étude de la problématique des opérations de dragages des zones portuaires sur les deux rives de la méditerranée : au nord les ports du golfe d’Aigues Mortes (France) et au sud le port de Ghar el Melah (Tunisie). L’étude porte sur le suivi de la remise en suspension de contaminants chimiques et microbiologiques au cours de ces opérations. L’état initial de la qualité des eaux et des sédiments avant les opérations de dragages est en cours dans le port de Carnon et une campagne d’échantillonnage est planifiée en juin 2022 dans le port de Ghar el Melah. Les suivis de la remise seront mis en place à l’automne qui permettront aux directions de ports de prendre des mesures de gestion et réduire ces contaminations si nécessaires. Un focus sera réalisé sur la comparaison de la gestion de ces opérations de dragage sur les deux rives de la méditerranée et la potentialité de réutiliser ces sédiments pour le rechargement des plages en érosion. Enfin des enquêtes de perception auprès des acteurs et usagers des ports sur le risque de submersion marine, sur la perception de la dégradation de la qualité des milieux, sur les opérations de dragage et la réutilisation des sédiments dragués, sur les usages sont en cours sur les différents sites en France et en Tunisie.

The alarming vulnerability of low-lying sandy beaches to the acceleration of global sea level rise has been confirmed in the recent IPCC AR6 report. The situation is worsened by increasing coastal erosion, resulting in additional shoreline retreat of sandy beaches along several semi-arid urban coastal areas around the globe. The additional shoreline retreats from erosion are indicative of the rising imbalance in coastal sedimentary processes, which are a direct consequence of changes in precipitation patterns, urban growth, and change in land use. To quantify the magnitude and timescale of both coastal erosion and sea-level rise (SLR) in generating shoreline retreat of sandy beaches in semi-arid urban areas, we combine photogrammetric and statistical methods to measure and forecast the decadal evolution of these coastlines using two well-characterized sites that are hypothesized herein to be globally representative of these types of coasts undergoing rapid urban growth. We use multi-decadal shoreline positioning and land use classification surveys of the Southern California (SC, USA) and the Hammamet-North (HAM, Tunisia) beaches from aerial and orbital photogrammetric images, combined with the Digital Shoreline Analysis System, for the period from 1985 to 2018. Our results suggest that the current average shoreline retreat rates of sandy beaches range from -0.75 to -1.24 m/yr in SC and from -0.21 to -4.49 m/yr in HAM under similar aridity, land coverage and precipitation patterns. The observed decadal changes in shoreline positions along these semi-arid urban coastal areas are found to be accentuated by anthropogenic drivers associated with extensive urbanization, causing sediment imbalance at the coastline, adding up to the effect of the accelerating SLR. We assess that ~81% and 57% of the observed shoreline retreat was due to SLR, and 19% to 43% due to coastal erosion from urban growth along SC and HAM beaches, respectively. Using these measured rates, we establish a semi-empirical numerical model that combines urban growth and the observed shoreline retreat rate to forecast retreat rates through 2100 for both of our study areas, inferred herein to be representative of other global semi-arid urban coasts. Our model suggests that future average total shoreline retreat rates, accounting for both urban growth and SLR, range from -2 to -4 m/yr for SC and HAM sandy beaches, respectively, through 2100. The above suggests that if no mitigation is made, by 2100 the cumulative shoreline retreat in these urban areas could significantly exceed the Global Scale Assessment Model’s [46] cumulative projected average retreat of -30 m, confirming the alarming vulnerability of the semi-arid coastal urban areas that would need intensive and costly beach nourishment to control increasing shoreline erosion.

The Suez Canal is a major bottleneck of global shipping. The stranding of the Ever Given, one of the world's largest container ships, in early 2021 showed how much global supply chains depend on the Suez Canal. The canal navigability directly depends on the incoming fluxes of sediments, either through the entrance on the Mediterranean Sea or from smaller tributaries along the canal. Here we model the hydrodynamics of the southeastern Mediterranean Sea, Suez canal and northern Gulf of Suez with the multi-scale ocean model SLIM (www.slim-ocean.be). The model can locally achieve a resolution of about 50 m and hence explicitly describes the flow through the narrow branches of the canal. The hydrodynamic model is then used to drive a sediment transport model that represents the dynamics of several types of sediments originating from the Nile delta, from shorelines along the Mediterranean Sea, and from inland channels connecting the Nile to the Suez Canal. Model results allow us to estimate the sediment deposition rate within the canal under present and future climate, and for different land and river management scenarios. The latter include the impact of existing and future dams along the Nile River and irrigation practices within the Nile Delta. Our result suggest that the Nile River management directly impacts the Suez canal navigability. This interconnection between the Nile River and the Suez Canal calls for an integrative management strategy.

The intensifying impacts of aridity and water stress on the dynamics and ecological degradation of wetlands in North Africa are often underestimated and largely remain unquantified. To address this deficiency, we assessed decadal changes in the sedimentary, sea surface salinity (SSS), and microfaunistic patterns of the Bizerte Lagoon, a climatically vulnerable area in the southern Mediterranean basin. Findings from sediment transport analysis indicate preferential current dispersion along the lagoon ridge associated with mixtures of sedimentary distributions. The changes in SSS between 2004 and 2016 reveal an increase of approximately 40% in areas where the river flows into the lagoon. Findings from the microfaunistic analysis suggest that over the last few decades, a progressive enrichment of alien marine species has occurred in the lagoon owing to changes in SSS and sedimentation. Results also revealed the unexpected presence of tropical to subtropical Larger B-bearing Foraminifera (LBF) species, which are exogenic to the warm southern Mediterranean coasts. The study findings highlight the impacts of damming and changes in precipitation patterns on the degradation of biodiversity in the Bizerte Lagoon and in other lagoonal systems in North Africa with similar levels of aridity.

Shoreline retreat along extended semi-arid areas of North African coasts are indicative of the imbalance of coastal sedimentary processes due to modern abrupt changes in precipitation patterns and urban growth. Monitoring of the diachronic shoreline position and land-use from 1952 to 2018 in the coast of the Hammamet Bay in central-east Tunisia, using both aerial and orbital photogrammetric scenes and the Digital Shoreline Analysis System from 1887 to 2018, suggests shoreline retreat rates ranging from −1.3 to −5.6 m/yr. Such rates are abnormal when compared to the average of −0.07 m/yr suggested by global-scale assessment modeling for sandy beach evolution. These abnormal erosions extend over 65 km of sandy beaches, resulting from a severe deficit of sediment transport caused primarily by rapid coastal urban growth that obstructs sediment flow to the shoreline. We suggest that the high retreat rates observed in the low-population period of 1884–1931 originated mainly from storm surges and tsunamis, or potentially subsidence in the coastal substratum. Moreover, our analysis of the salinity of shallow coastal aquifers and land coverage suggests that shoreline retreat coupled with rapid urban growth accelerated seawater intrusion ~5 km inland, causing soil desiccation, the development of salt lakes, and reduction of vegetation coverage by ~18%. These abrupt environmental changes have a severe, adverse impact on crop production and food security in these densely populated and economically important areas across significant parts of the North African coasts, sharing similar key environmental parameters with our study site. We conclude that anthropogenic drivers are the major source of shoreline retreat rather than natural ones.

International audience; As coastal areas become increasingly vulnerable to climate change, the study of nearshore sediment textures along the littoral cell of the Medjerda delta in the Gulf of Tunis, southern Mediterranean coast can provide valuable information (i) on the origin (continental or marine) of the sediment, (ii) its transport direction, and (iii) constitutes an important tool in the assessment of coastal sensitivity. A total of 120 sediments samples underwent grain size analysis and statistic parameters have been calculated. These allowed the identification of five different Sedimentary Types (ST). Accordingly, using grain size indexes (i.e. Mz, SKI and Ku), Sediment Trend Analysis (STA) modeling tools were applied to define the seasonal sediment transport pathways throughout the nearshore of the Medjerda sedimentary cell. Results show that grain size distribution (GSD) and STA model pathways are determined by cross-shore geomorphology, location of the sediment-cell, seasonal incident wave and local terrestrial supply. The appearance in an atypical seabed location of the finer (Mo = 0.1 mm) and the coarser STs (Mo = 0.8 mm) can be indicative of human influence since the coarser particles are usually retained by dam structures. Moreover, the bimodality and the increased distribution of mud are also related to the seasonal incident wave winnowing of the historic deltaic plain submerged by the relative rise in sea level. The evolution of the sediment pattern towards a greater proportion of very fine grains indicates a deficit of sediment supply, particularly of the coarser grains, and demonstrates the coastal vulnerability of the Gulf of Tunis due to anthropic effects.

The FRIEND-Water program (FWP) is the oldest and the most transverse program (i.e. Flagship Initiative) within the Hydrological Intergovernmental Program (IHP) from UNESCO. FRIEND means “Flow Regimes from International and Experimental Network Data”. The FWP is dedicated to allow large communities of hydrologists and associated disciplines to collaborate across borders on common shared data and scientific topics which are addressed through large world regions. The program has evolved in its 35 years of existence. There are 8 large regions in the world which gather tenths of hundreds of researchers, and organize events following several research topics defined according to each region priorities. The FWP is chaired by a scientific committee gathering regional coordinators and thematic experts. Each region gives its research priorities which evolve according to the projections given by the member States during the IHP council every year. The future activities of the FWP are defined by the upcoming IHP IX program and with the support of the newly created Montpellier UNESCO Category II Center ICIREWARD, acting as FWP Secretariat.

The arid coasts of North Africa, extending over 4633 km from the Gulf of Tunis to the Nile Delta, are undergoing pronounced shoreline retreats and coastal floodings that are reported as a consequence of the ongoing sea level rise resulting from global warming. Of particular interest are the abnormal shoreline dynamics for deltaic and sandy beaches, which are severely impacted by abrupt decadal variabilities in both climatic and anthropogenic drivers resulting in their increased vulnerability to disturbances from coastal hazards. Unfortunately, the evolution, distribution and impacts of these drivers remain largely unquantified, let alone understood, for these extensive arid coasts that harbor the major portion of North Africa’s population as well as unique and fragile marine ecosystems. To address this deficiency, we use GIS-based multi-criteria approaches combined with analytic hierarchy process to map the Coastal Vulnerability Index and the Socioeconomic Vulnerability Index along these coasts to investigate the amplitude and extent of shoreline deterioration resulting from sudden fluctuations in sediment transport to the coastline. We use the western bay of the Gulf of Tunis, the coasts of Tripoli and the Nile Delta as three validation sites for our vulnerability assessment. The statistical Integrated Coastal Vulnerability Index map reveals that 47% of arid North African coasts are characterized by high to very high vulnerability. In particular, we observe that the densely populated deltaic coasts in both Tunisia and Egypt are 70% more vulnerable than any others coast in the eastern Mediterranean Basin. These abnormally high-vulnerability extensive areas are also correlated with significant deterioration of coastal aquifers and hence in crop production, compromising local food security and resulting in increasing outflow migration trends. Both Tunisia and Egypt observed dramatic increases in the net population outflow migration by respectively 62% and 248% between 2000 and 2016, mostly from coastal areas. Our source analysis of the amplitude and extent of these high coastal vulnerabilities suggests that they result from the anthropogenic drivers of damming and rapid urban growth over the last few decades rather than the effects of global warming.

The sedimentary contributions of the Medjerda to the coastal zone are poorly measured, and there is no chronicle of observations. In this context, the sediment monitoring appears indispensable for the quantification of sediment transport at the outlet. This study focuses on the largest watershed in Tunisia, the Wadi Medjerda (23 600 km2). The main objective of this work is to assess the reduction of sediment transport following anthropogenic intensification on the basin, especially since the construction of many large dams. In order to collect information on actual deposits over several years, the paleo-hydrological approach was applied through the study of sediment cores sampled in the low valley meanders on alluvial terraces, after the last dam (Sidi Salem, the largest water storage capacity over the basin), but before the estuary to avoid marine influence and near a hydrological station (Jdaida). The sedimentary deposits of the river provide key information on the past sedimentary inputs. A visible succession of sedimentary layers corresponding to the deposits of successive floods on the study site has been determined and the history of the sedimentary contributions of the Medjerda is reconstructed by this approach. The thickest layers of sedimentary deposits are related to exceptional events. They are mainly concentrated on the lower part of the core and are mainly composed of sands. The first 1.2 m of the core from the bottom upward relates to 10 years of river discharges, as can be determined from the 137Cs datation. The next upward 1.05 m of core relates to the following 20 years of discharges, up to 1981, date of the construction of the Sidi Salem dam, and is composed of a mix of sand, silts and clays. The last 75 cm of core near the surface is only composed of clays with thin silt bands, and relates to a period of 32 years. We thus observe that there is no more sand deposits in the river bed since the construction of the Sidi Salem dam. The deficit of sediment supply to the sea is viewed as a major factor to be taken into account for better understanding of the dynamics of coastal areas in the context of global climate change.

The aim of this study consists in testing the effectiveness of satellite data in order to monitoring shoreline and sedimentary features changes, especially the rapidly changing of Gulf of Tunis coast. The study area is located in the Gulf of Tunis western bay (Southern Mediterranean Sea) which is characterized by sandy beaches of Ghar Melah and Raoued (Medjerda Delta area). The aerial photographs and satellite imageries were used for mapping the evolution of shoreline. Diachronic data (satellite imagery, aerial photography and topographic maps) were used to monitor and to quantify, the evolution of the coastal areas. These thematic data were digitally overlaid and vectorised for highlighting the shoreline changes between 1936 and 2016, in order to map the rate of erosion and accretion along the shoreline. Results show that the accretion and degradation are related to the Medjerda: change of outlet in 1973 and impoundment of the Sidi Salem dam in 1982. We found that the general trend of the coastal geomorphic processes can be monitored with satellite imageries (such as Sentinel A2, Spots 4 and 5), due to its repetitive coverage along the time and their high quality concerning the spectral contrast between land and sea areas. Improved satellite imageries with high resolution should be a valuable tool for complementing traditional methods for mapping and assessing the sedimentary structures (such as shoreline, delta, marine bars), and monitoring especially the lowlands coastal areas (slightly eroded).

The geochemical and grain size analysis were carried out on surface and down core sediments from the present-day alluvial-coastal plain of the Medjerda River, Gulf of Tunis, Tunisia. The aim of this paper is to characterize the geochemical and grain size distribution of sediments and its relationship with the hydrodynamics extreme events occurring during the last century. Using a multi proxy approach, six turbidities layers have been identified in down core sediment (i.e. TL-1, TL-2, TL-3, TL-4, TL-5, TL-6, TL-7 and TL-8) characterized by multimodal grain size distribution. The terrestrial sediment which feeds the northern coastal of the Gulf of Tunis is characterized by very fine-grained sediment (clay and silt). The geochemical signature shows a highly concentration of Rb, Ti, Zn and Pb. The Medjerda River is the mainly source of silts and clay sediment. Besides, the mining pollution (Zn and Pb) is relatively strong in the coastal area, especially during the great floods events of Medjerda watershed recorded in the 1953; 1957; 1969 and 1973. Even during high frequency events, the sediments are devoid of any coarse fraction.

The aim of this study is the reconstitution of the recent morpho-sedimentary evolution of the Medjerda River delta. We examine the spatio-temporal evolution of the Medjerda shoreline between 1936 and 2016 using satellite images, complemented by sedimentological and geochemical analyses and (210)Pbex and (137) Cs radiometric data. The general tendency of the shoreline evolution shows an increasing progradation (300 +/- 12 m) between 1936 and 2016. Yet the mesoscale Net Shoreline Movement position (NSM) and the End Point Rate (EPR) reveal an erosion pattern estimated to be -20 m +/- 0.15 m/yr during the period 1988-1999. The sedimentological analyses reveal four main lithostratigraphic units. The fine sand substratum layer (Md = 0.08 mm) decreases toward clay and silt facies (Md < 0.063 mm), rich in continental plant debris. The geochemical results reveal gradual incoming of the terrigenous component instead of marine deposits. The Cs-137/(210) Pbex radiometric dating confirms the functioning of the new river flow by the 1950s with the highest sedimentation rate being 3.3 cm/yr. Our results show that the Sidi-Salem dam impoundment (1981) led to a dramatic reduction of sediment discharge, a decrease of the grain size with nearly no more sand reaching the coast, and the shoreline retreat.

The present work is based on The RYSCMED project supported by PHC-UTIQUE 2016-2018 (16G 1005 –34854QC). The RYSCMED is an interdisciplinary project which gathers different disciplines (e.g. sedimentology, hydrology, geochemistry, ecology, paleontology, biochemistry, archeology) to quantify the sediment flow of the land-sea. This research aims at identifying coastal sediment dynamics (via the sand supply sources; i.e. Medjerda River) and hydrodynamic parameters to understand the local environmental problems in an urbanized coastal framework. The outcome is expected to produce original and new findings about the link between dams, river hydrology and sediment origin to the sea, with the impact of climate and anthropogenic activities on the coastal geomorphology and ecosystem sensitivity. The main scientific outcome will be addressed to the socio-economic actors to implement necessary solutions for remediating the Mediterranean coastal vulnerability. (Abstract author)

Sediments are important carriers of pollutants and they help greatly in describing the aquatic ecosystem relating state. The aim of this study is to characterize the Kalaât Andalous harbor lagoon sediments’ grain size, their spatial distribution as well as their relating quality. To this end, a study of their trace elements content has been conducted to highlight the associated natural and anthropogenic contribution. Hence, twelve subsurface lagoon sediment samples were extracted at the level of six radials and subjected to a granulometric analysis. The calculation of such indexes as the average mean size (MZ), sorting index (σ) and asymmetry index (SKI) helped greatly in defining the grain size-distribution character. Samples underwent different analyses in a bid to evaluate seven trace metals relevant rates (As, Cd, Cr, Cu, Ni, Pb, Zn). The obtained metal concentrations were compared to the American Oceanic and Atmospheric Administration (NOAA) guidelines, ERL and ERM. The enrichment factor (EF) analysis is used to assess the contamination level, and distinguish both of the relating natural and anthropogenic origin sources. The reached results proved to display that the sediments turn out to be predominantly sandy, with fine sand dominating the area, while medium sand is being located at the channel and the south-western section of the quay. The latter is characterized with a muddy facies. The majority of trace elements’ concentrations are discovered to be lower than the ERL values. The implemented enrichment factors proved to indicate that the lagoon is mainly enriched in As and Cd.

Coastal lagoons are among the highest biological productive ecosystems; they offer a variety of habitats and feeding grounds for several species. These ecosystems are besmirched by human activities which entail the degradation to their environmental aspects. The purpose of this study is the identification of the grain-size characteristics and the unprecedented recognition of the vegetation cover, so as to assess the ecological state and the water body quality of Kalâat Andalous lagoon: a fast changing ecosystem under its dynamic sandy spit and human pressures. The methodology is based on the sedimentological analysis and the microfauna identification. The study of the environmental quality of the lagoon was built on an unprecedented identification of the macrophyte communities and the use of diversity indexes and the EXCLAME indicator; the latter combines the taxonomic composition and the species abundance. The sedimentological investigations showed that the northern and southern areas of the lagoon, as well as its channel area are all dominated by a sandy facies provided by the continental shelf i.e. the nearshore zone. The central area of the lagoon is characterized by the finest grain size facies (

The aim of this study is to monitor the sediment pattern of the coastal lagoon of Bizerte in order to assess the human/natural effect on the environmental dynamic system. The methodology is based on a sedimentological study associated to Sediment Trend Analysis, STA model (Sunamura and Horikawa 1971) in order to update the grain size distribution of submarine sediment to better understanding the related relationship with hydrodynamic trend as well. A paleontological study was carried out allowing the identification of the micro faunistic changes related to the lagoon properties. The sediment transport model applied to granulometric indexes (Mz, sorting and SKI) reveals a preferential dispersion of a mixture of sedimentary structure along of the coast that converge towards the center of the lagoon, very similar to the hydrodynamic conditions of the lagoon.

Proceedings of Euro-Mediterranean Conference for Environmental Integration (EMCEI-1), Tunisia 2017; A great number of rivers of North Africa are equipped with many dams for multiple purposes, mainly potable water, irrigation and energy production. In most of the countries—Morocco, Algeria and Tunisia, the storage capacity exceeds the runoff capacity, which means that water is stored several times in a row during its course to the sea.

Shorelines are defined as an interface where natural, anthropogenic, socio-economic constraints are exacerbated and constantly changing.

The dredging of the navigation channel of the Port of Kalâat Andalous is an important technical operation for the maintenance of the harbor activities.

The coastal system is a fragile and unstable environment. The demographic pressure together with the importance of industrial and economic issues associated requires taking awareness of the fragility of coastal fronts.

Lagoons are defined as paralic environments. These ecosystems constitute sensitive productive environments. They receive many inputs from the watershed. The organization and characteristics of lagoon environments are closely dependent on the balance between marine and continental influences.