A Comprehensive Estuarine Hydrodynamics-Salinity Study: Impact of Morphologic Changes on Ria de Aveiro (Atlantic Coast of Portugal)

Shallow coastal lagoons driven by tidal processes are extremely dynamic environments prone to continuous natural and anthropogenic pressures. The hydrodynamics of these systems deeply depends on the effect of local morphology on the tidal propagation, so their permanent evolution constantly changes tidal dependent processes. For this reason, the present work aims to review the main characteristics of Ria de Aveiro hydrodynamics, a shallow lagoon located at the Atlantic Coast of Portugal, evaluating its evolution over the last 30 years (between 1987 and 2020) and investigating the main morphological changes in its origin. For this purpose, a comparative analysis is performed to determine the main process, including the observed hydrodynamic changes: Deepening of the inlet channel or of the main lagoon channels. To achieve these goals, the authors explored a remarkable database including bathymetric, tide gauge, and salinity data from 1987 until the present. This analysis is completed by the exploitation of a hydrodynamical model (Delft3D), validated against field data. Several simulations were performed to analyse changes in tidal propagation along the lagoon channels (considering the main semi-diurnal constituent M2), tidal asymmetry, tidal currents, tidal prism, and salinity patterns. The results show that the general deepening of the lagoon observed between 1987 and 2020 led to important changes in the lagoon hydrodynamics, namely the increase/decrease of the M2 constituent amplitude/phase, as well as the increase of tidal currents and salt intrusion within the entire lagoon, with the changes being amplified towards the head of the main channels. Although the inlet deepening partially contributed to the modifications found, the results revealed that the deepening of the main lagoon channels had the most significant contribution to the changes observed during the last 30 years.

Download Full-text

STUDY OF MORPHODYNAMIC AND SEDIMENTOLOGICAL CHANGES IN THE OUALIDIA LAGOON (MOROCCO) USING BATHYMETRIC DATA: FIRST INVESTIGATIONS AFTER THE SEDIMENT TRAP DREDGING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlvi-4-w3-2021-53-2022 ◽

2022 ◽

Vol XLVI-4/W3-2021 ◽

pp. 53-63

Author(s):

M. Bouchkara ◽

K. El Khalidi ◽

A. Benazzouz ◽

N. Erraji Chahid ◽

I. Joudar ◽

...

Keyword(s):

Sediment Trap ◽

Morphological Changes ◽

Coastal Lagoons ◽

Atlantic Coast ◽

Average Height ◽

Bathymetric Data ◽

Tidal Propagation ◽

Oualidia Lagoon ◽

Gis Environment ◽

Development And Management

Abstract. Coastal lagoons are highly dynamic and physically complicated systems. They are environmentally productive and socio-economically valuable. Contemporary global development and management pressures require a better understanding of their dynamics and sustainability. The present study focuses on the problem of water confinement in the Oualidia lagoon (Atlantic coast of Morocco). This lagoon is characterized by an asymmetric tidal propagation, with a shorter duration of the flood (rising tide) than the ebb (falling tide). In the long term, this contributes to the reduction of depths and the confinement of water upstream. After extensive studies, a sediment trap was created in 2011 to trap the finest sediment in the upstream part of the lagoon. This study aims to analyze the morphodynamical and sedimentological changes in the lagoon of Oualidia, after the sediment trap dredging. For this purpose, bathymetric surveys covering 6 years between 2006 and 2012 were analyzed, providing sufficient data to identify the morphological changes that the lagoon has undergone during this period. The data analysis was followed by a study of the lagoon bed dynamics using profile lines extracted from the bathymetric data in a GIS environment. As a result, the findings partly show that over 6 years, an average height of +0.65 m was gained by the lagoon, while the average change in the eroded areas was estimated to be −0.42 m. In addition, the eroded area in the lagoon was estimated to be about 1,513,800 m2 with an erosion volume of 633,383 m3, while the accumulated area found was about 2,699,396 m2 with an accumulation volume of 1,765,866 m3. These changes can be related to the large input of marine sediment, mainly caused by tidal currents and waves, but also to the creation of a sediment trap in the upstream area of the lagoon.

Download Full-text

Nearshore circulation revealed by wastewater discharge from a submarine outfall, Aveiro Coast, Portugal

Hydrology and Earth System Sciences ◽

10.5194/hess-6-983-2002 ◽

2002 ◽

Vol 6 (6) ◽

pp. 983-988 ◽

Cited By ~ 6

Author(s):

J. Figueiredo da Silva ◽

R. W. Duck ◽

T. S. Hopkins ◽

J. M. Anderson

Keyword(s):

Atlantic Coast ◽

Climatic Conditions ◽

Wastewater Discharge ◽

Inlet Channel ◽

Ria De Aveiro ◽

Shelf Circulation ◽

The North ◽

Nearshore Circulation ◽

Estuarine Coastal

Abstract. The morphological and climatic conditions of the Atlantic coast of northern Portugal result in a prevailing upwelling circulation over the continental shelf. A submarine outfall releases wastewater into the ocean c. 3 km directly offshore (at ∼16 m water depth) from S. Jacinto, 5 km to the north of the inlet to the estuarine coastal lagoon system of the Ria de Aveiro. The buoyant plume has a distinctive reddish brown colour and is clearly visible at the water surface. The transport and dispersion of the plume was monitored by airborne photography and by in situ water sampling. Results revealed the surface currents present and water mass fronts in the nearshore zone of the Aveiro coast. During the spring and summer, the plume was not transported offshore in the manner expected by the upwelling shelf circulation. Instead, it was commonly observed to be transported alongshore with the prevailing southerly circulation or with an onshore component. The transport to the south caused the outfall plume to interact with the circulation associated with the tidal currents generated in the inlet channel to the Ria de Aveiro. The observations suggest that the trophic status of the Ria de Aveiro is unlikely to change because of the operation of the submarine outfall. Furthermore, this study demonstrates how simple observations of wastewater discharge from a submarine outfall can be used to improve understanding of nearshore circulation. Keywords: water circulation, upwelling, ocean outfall, remote sensing, eutrophication, Ria de Aveiro

Download Full-text

Monitoring Skeletal Anomalies in Big-Scale Sand Smelt, Atherina boyeri, as a Potential Complementary Tool for Early Detection of Effects of Anthropic Pressure in Coastal Lagoons

Water ◽

10.3390/w13020159 ◽

2021 ◽

Vol 13 (2) ◽

pp. 159

Author(s):

Chiara Leone ◽

Francesca De Luca ◽

Eleonora Ciccotti ◽

Arianna Martini ◽

Clara Boglione

Keyword(s):

Early Detection ◽

Habitat Degradation ◽

Anthropogenic Impacts ◽

Coastal Lagoons ◽

Ecological Status ◽

Detection Methods ◽

Anthropogenic Pressures ◽

Morphological Examination ◽

Skeletal Anomalies

Mediterranean coastal lagoons are increasingly affected by several threats, all concurrently leading to habitat degradation and loss. Methods based on fish for the assessment of the ecological status are under implementation for the Water Framework Directive requirements, to assess the overall quality of coastal lagoons. Complementary tools based on the use of single fish species as biological indicators could be useful as early detection methods of anthropogenic impacts. The analysis of skeletal anomalies in the big-scale sand smelt, Atherina boyeri, from nine Mediterranean coastal lagoons in Italy was carried out. Along with the morphological examination of fish, the environmental status of the nine lagoons was evaluated using a method based on expert judgement, by selecting and quantifying several environmental descriptors of direct and indirect human pressures acting on lagoon ecosystems. The average individual anomaly load and the frequency of individuals with severe anomalies allow to discriminate big-scale sand smelt samples on the basis of the site and of its quality status. Furthermore, a relationship between skeletal anomalies and the environmental quality of specific lagoons, driven by the anthropogenic pressures acting on them, was found. These findings support the potentiality of skeletal anomalies monitoring in big-scale sand smelt as a tool for early detection of anthropogenic impacts in coastal lagoons of the Mediterranean region.

Download Full-text

Testing an “IoT” Tide Gauge Network for Coastal Monitoring

IoT ◽

10.3390/iot2010002 ◽

2021 ◽

Vol 2 (1) ◽

pp. 17-32

Author(s):

Philip Knight ◽

Cai Bird ◽

Alex Sinclair ◽

Jonathan Higham ◽

Andy Plater

Keyword(s):

Sea Level ◽

Morphological Changes ◽

Tide Gauge ◽

Low Cost ◽

Pressure Sensors ◽

Wave Activity ◽

Tide Gauges ◽

Coastal Monitoring ◽

Level Data ◽

Operational Constraints

A low-cost “Internet of Things” (IoT) tide gauge network was developed to provide real-time and “delayed mode” sea-level data to support monitoring of spatial and temporal coastal morphological changes. It is based on the Arduino Sigfox MKR 1200 micro-controller platform with a Measurement Specialties pressure sensor (MS5837). Experiments at two sites colocated with established tide gauges show that these inexpensive pressure sensors can make accurate sea-level measurements. While these pressure sensors are capable of ~1 cm accuracy, as with other comparable gauges, the effect of significant wave activity can distort the overall sea-level measurements. Various off-the-shelf hardware and software configurations were tested to provide complementary data as part of a localized network and to overcome operational constraints, such as lack of suitable infrastructure for mounting the tide gauges and for exposed beach locations.

Download Full-text

On the different assessments of present velocity and acceleration in a tide gauge record characterized by a quasi-60-year periodic oscillation: comment to “Parker A., oscillations of sea level rise along the Atlantic coast of North America north of Cape Hatteras, natural hazards, in press, accepted manuscript”

Natural Hazards ◽

10.1007/s11069-013-0580-7 ◽

2014 ◽

Author(s):

Thomas Watson ◽

Alberto Boretti

Keyword(s):

North America ◽

Sea Level Rise ◽

Sea Level ◽

Natural Hazards ◽

Tide Gauge ◽

Atlantic Coast ◽

Periodic Oscillation ◽

Tide Gauge Record ◽

Cape Hatteras ◽

North America North

Download Full-text

Tidal propagation in Ria de Aveiro Lagoon, Portugal

Physics and Chemistry of the Earth Part B Hydrology Oceans and Atmosphere ◽

10.1016/s1464-1909(00)00028-9 ◽

2000 ◽

Vol 25 (4) ◽

pp. 369-374 ◽

Cited By ~ 114

Author(s):

J.M. Dias ◽

J.F. Lopes ◽

I. Dekeyser

Keyword(s):

Ria De Aveiro ◽

Tidal Propagation ◽

Aveiro Lagoon

Download Full-text

Living benthic Foraminifera from the Saquarema lagoonal system (Rio de Janeiro, southeastern Brazil)

Check List ◽

10.15560/13.2.2062 ◽

2017 ◽

Vol 13 (2) ◽

pp. 2062 ◽

Cited By ~ 4

Author(s):

Pierre Belart ◽

Vanessa Mattos Laut ◽

Iara Martins Moreira Matos Clemente ◽

Débora Silva Raposo ◽

Virgínia Martins ◽

...

Keyword(s):

Benthic Foraminifera ◽

Rio De Janeiro ◽

Coastal Lagoons ◽

Southeastern Brazil ◽

Anthropogenic Pressures ◽

Foraminiferal Assemblage ◽

Complex Ecosystem ◽

Benthic Foraminiferal Assemblage ◽

Janeiro State ◽

Transitional Environments

Transitional environments such as coastal lagoons with narrow connections to the sea are ecosystems very sensitive to natural or anthropogenic pressures. They are biodiversity hotspots and for this reason it should be studied and preserved. This study lists the benthic Foraminifera species from the Saquarema lagoonal system (SLS), Rio de Janeiro state, Brazil. This complex ecosystem consists of four large connected lagoons, namely Urussanga, Jardim, Boqueirão, and Saquarema. A poorly diversified benthic foraminiferal assemblage was documented from most of the lagoon system and consisted of only eight species belonging to three orders and four families. The relatively low species richness of the SLS compared to other Brazilian coastal lagoons might be explained by several factors including domestic sewage input and the long residence time of water.

Download Full-text

The use of benthic metabolic processes as indicators for environmental quality assessment in coastal lagoons

Advances in Oceanography and Limnology ◽

10.4081/aiol.2013.5344 ◽

2013 ◽

Vol 4 (2) ◽

pp. 194 ◽

Cited By ~ 4

Author(s):

E. Arévalo ◽

J.S.P. Ibánhez ◽

S. Papaspyrou ◽

A. Nicolaidou

Keyword(s):

Organic Matter ◽

Quality Assessment ◽

Environmental Quality ◽

Coastal Lagoons ◽

Nutrient Content ◽

Anthropogenic Pressures ◽

Overlying Water ◽

Environmental Quality Assessment ◽

Water Composition ◽

Solute Fluxes

The review highlights the various methods used for assessing environmental quality in Mediterranean coastal lagoons, with emphasis on benthic parameters and processes. The application of indices based on benthic macrofauna, extensively used in coastal areas, may fail in discerning between natural and anthropogenic pressures over naturally stressed coastal lagoons. Sediment can play an important regulatory role over the overlying water composition through the storage capacity for organic matter and pollutants, regeneration of nutrients or its buffering capacity. Descriptive classical measurements like sedimentary organic matter, Chlorophyll α and nutrient content are commonly included in monitoring efforts. However, other more complex indicators like primary production, sediment-water solute fluxes, solute sorption dynamics or microbial reaction rate determinations, have not been fully implemented for environmental quality assessment in coastal lagoons. These could offer crucial information on current and projected anthropogenic influence on ecosystem functioning. Irruption of novel techniques in benthic biogeochemistry like Excitation-Emission-Matrix (EEM) fluorescence for the study of dissolved organic matter dynamics shows high potential in combination with biological quality elements and other metabolic measurements for the evaluation of the environmental quality in coastal lagoons.

Download Full-text

Unraveling The Impacts of Meteorological and Anthropogenic Changes on Sediment Fluxes Along an Estuary-Sea Continuum

10.21203/rs.3.rs-677174/v1 ◽

2021 ◽

Author(s):

Florent Grasso ◽

Eliott Bismuth ◽

Romaric Verney

Keyword(s):

Human Activities ◽

River Flow ◽

Morphological Changes ◽

Large River ◽

Fine Sediment ◽

Global Changes ◽

Anthropogenic Pressures ◽

Estuarine Ecosystem ◽

Anthropogenic Changes ◽

Sediment Fluxes

Abstract Sediment fluxes at the estuary-sea interface strongly impact particle matter exchanges between marine and continental sources along the land-sea continuum. However, human activities drive pressures on estuary physical functioning, hence threatening estuarine habitats and their ecosystem services. There is an increasing societal need to better predict the potential trajectories of estuarine sediment fluxes resulting from natural and anthropogenic pressures, but the concomitance of human-induced and meteorological-induced changes makes the responses ambiguous. Therefore, this study explores a 22-year numerical hindcast, experiencing contrasted meteorological conditions and human-induced morphological changes (i.e., estuary deepening and narrowing), in order to disentangle the relative contributions of meteorological and anthropogenic changes on net sediment fluxes between a macrotidal estuary and its adjacent coastal sea. Our results highlight that intense wave events induce fine sediment (≤100 µm) export to the sea but coarser sediment (≥210 µm) import within the estuary. Remarkably, moderate to large river flows support mud import within the estuary. Over 25 years, the reduction of intense wave and river flow events reduces fine sediment export to the sea. In addition, the estuary morphological changes due to human activities increase fine sediment import within the estuary, shifting the estuary from an exporting to importing system. We propose a conceptualization of mud flux response to river flow and wave forcing, as well as anthropogenic pressures. It provides valuable insights into particle transfers along the land-sea continuum, contributing to a better understanding of estuarine ecosystem trajectories under global changes.

Download Full-text