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

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.

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

2021 ◽  
Vol 9 (2) ◽  
pp. 234
Author(s):  
João Miguel Dias ◽  
Francisco Pereira ◽  
Ana Picado ◽  
Carina Lurdes Lopes ◽  
João Pedro Pinheiro ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Tide Gauge ◽  
Coastal Lagoons ◽  
Atlantic Coast ◽  
Tidal Currents ◽  
Main Process ◽  
Anthropogenic Pressures ◽  
Inlet Channel ◽  
Ria De Aveiro ◽  
Tidal Propagation

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.

scholarly journals Contribution to the reproduction of Ruditapes decussatus in Oualidia lagoon and Dakhla bay (North West African Atlantic Coast)

2018 ◽  
Vol 5 ◽  
Author(s):  
Kaoutar HIMMI ◽  
Oum Keltoum BELHSEN ◽  
Mohamed ID HALLA ◽  
Yassine OUAGAJJOU ◽  
El Mustapha AIT CHATTOU ◽  
...  
Keyword(s):  
Atlantic Coast ◽  
West African ◽  
Ruditapes Decussatus ◽  
North West ◽  
Oualidia Lagoon ◽  
Dakhla Bay ◽  
African Atlantic

scholarly journals Morphological Changes along the shoreline of the arcuate Niger Delta from Parts of Delta State to Akwa Ibom State between 1986 and 2016

2021 ◽  
Vol 13 (1) ◽  
pp. 221-234
Author(s):  
Gordon Tami Amangabara ◽  
Obinna Michael Onyewuchi
Keyword(s):  
Niger Delta ◽  
Morphological Changes ◽  
Anthropogenic Activities ◽  
Shoreline Change ◽  
Shoreline Erosion ◽  
Vegetative Cover ◽  
Shoreline Changes ◽  
Precautionary Measures ◽  
Gis Environment ◽  
Landsat Satellite

This study analyzes the morphological changes occurring at the arcuate Niger Delta shoreline by identifying factors that contribute to erosion-induced shoreline changes and the rate of shoreline change from Forcados (Delta State) to Ibeno (Akwa Ibom State). Shoreline changes were compared from 1986 to 2016 as well as among western, central and eastern sections of the arcuate Niger Delta using Landsat satellite imagery within Geographic Information System (GIS) environment. In the assessment of the entire shoreline, accretion was 5,477.814Ha (1.2%) in 1986 and 19181.53Ha (4.1%) in 2016. For erosion, it was 48,400.03 (10.3%) in 1986 and 68398.84Ha (14.5%) in 2016. This indicates that accretion increased by 2.91% and erosion also increased by 4.25% in 30 years. The major accretion was detected within Brass (Bayelsa State), Bonny (River State), Andoni (River State) and Ibeno (Akwa Ibom State). Forcados South Point (Delta State), Sombreiro River mouths and eastern Obolo recorded the highest level of shoreline erosion. For land use/land cover (LULC), vegetation was 27.4% in 1986 but reduced to 22.9% in 2016; a change I attributed to massive conversion of vegetative cover for anthropogenic activities in the area. The study concluded that major erosion cases are due to the changing climate and the velocity of flow of major estuaries into the ocean. The activities that contribute to the shoreline change aside the challenging natural factors are sand mining, hard and engineered structures on the shore and other commercial and social activities. The occurrences of shoreline erosion have contributed to the degradation of these coastal ecosystems, loss of human settlements and livelihood. It is therefore essential to implement precautionary measures to mitigate the risk of shoreline erosion within this sensitive zone

Macrofaunal patterns and animal–sediment relationships in Uruguayan estuaries and coastal lagoons (Atlantic coast of South America)

2014 ◽  
Vol 87 ◽  
pp. 46-55 ◽  
Author(s):  
L. Giménez ◽  
N. Venturini ◽  
N. Kandratavicius ◽  
M. Hutton ◽  
A. Lanfranconi ◽  
...  
Keyword(s):  
South America ◽  
Coastal Lagoons ◽  
Atlantic Coast

scholarly journals Catch variability and growth of pink shrimp (Farfantepenaeus paulensis) in two coastal lagoons of uruguay and their relationship with ENSO events

2015 ◽  
Vol 63 (3) ◽  
pp. 355-362
Author(s):  
Orlando Santana ◽  
Santiago Silveira ◽  
Graciela Fabiano
Keyword(s):  
Growth Parameters ◽  
Coastal Lagoons ◽  
Atlantic Coast ◽  
Natural Populations ◽  
Negative Relationship ◽  
Pink Shrimp ◽  
Larval Stages ◽  
Enso Events ◽  
Farfantepenaeus Paulensis ◽  
Commercial Size

AbstractThe pink shrimp Farfantepenaeus paulensis (Pérez Farfante, 1967) is distributed along the Atlantic Coast from Bahia (Brazil) to Mar del Plata (Argentina). The larval stages enter the Uruguayan brackish water lagoons during late spring to summer associated with tidal currents of the Brazilian Current. In such environments the growth is accelerated and in early autumn the individuals attain commercial size, supporting important regional artisanal fisheries. The pink shrimp catches from 1988 to 2013 were analyzed and related to phenomena of climate variability in ENSO events and to the growth of the species. The total catch ranges from 0.7 to 162 tons. The variation in catches has a negative relationship with the varied climatic events caused by El Niño. Growth parameters yielding values of L ∞ = 177 mm (total carapace length) and K = 1.48 for the period 2009-2013. These values differ slightly from those calculated for natural populations in southern Brazil, suggesting that the population is the same and thus implying the need for coordinated fisheries management between the two countries.

Natural valuation of the Polish marine areas (Baltic) based on phytobenthos

2018 ◽  
Vol 33 (1) ◽  
pp. 149-157
Author(s):  
Paulina Brzeska-Roszczyk ◽  
Lidia Kruk-Dowgiałło
Keyword(s):  
Surface Sediments ◽  
Coastal Lagoons ◽  
Point Of View ◽  
Protected Species ◽  
Qualitative And Quantitative ◽  
Bathymetric Data ◽  
Valuation Method ◽  
Simple Tool ◽  
Marine Areas ◽  
Values Distribution

The aim was to develop a method for assessing the natural values of the Polish marine areas (PMA), excluding coastal lagoons, based on phytobenthos. The valuation method includes 4 criteria which refer to the qualitative and quantitative structure of phytobenthos. The method was tested at the stony bottom overgrown with macroalgae – in the coastal zone, near the localities of Ustka, Poddąbie and Rowy. The assessment showed that the most valuable was the boulder area in the vicinity of Rowy, due to the presence of macroalgae communities with 5 rare and 3 protected species. The least valuable was the stony bottom near Ustka, with small amounts of macroalgae and 1 protected species. The natural values were classified into four classes and presented on map, what is very important from the practical point of view, especially when consider areas designated for future investments. The map with natural values distribution was created on the layers of surface sediments, which were developed on the basis of sonar and bathymetric data. The use of these data allowed the precise delineation of subareas with different natural values. The natural valuation method presented in this article is a relatively simple tool that can be applied to determine the areas valuable in terms of phytobenthos in PMA.

scholarly journals GEOMORPHOLOGICAL AND BATHYMETRIC RESEARCH ON LAKES ZERELIA OF ALMYROS (CENTRAL GREECE)

2017 ◽  
Vol 50 (1) ◽  
pp. 315
Author(s):  
A. Gaitanopoulos ◽  
K. Albanakis ◽  
K. Vouvalidis
Keyword(s):  
Information System ◽  
Geographic Information System ◽  
High Resolution ◽  
Large Scale ◽  
Surrounding Area ◽  
Geometric Characteristics ◽  
Central Greece ◽  
Bathymetric Data ◽  
Area Of Interest ◽  
Gis Environment

The area of interest is located close to Almyros city, at the prefecture of Magnesia (Central Greece), where the twin lakes Zerelia are situated. The origin of these twin lakes is not clear, however, many hypotheses have been proposed over the years. A lack of large-scale mapping in the surrounding area and a high resolution spatial depiction of the topography, hinders the extractionof conclusions on the twin lakes' origin. Also, previous studies have focused on surficial evidence to support hypotheses, rather than investigating the geometric characteristics and the spatial lay-out of the twin lakes. Filling this gap, measurements of depth via sonar in Zerelia lakes were performed. The bathymetric data along with the digitized, high-resolution topographic data of the surrounding terrain were imported in a Geographic Information System (GIS) environment. The area was depicted with high accuracythrough DEMs and conclusions for the landscape were extracted. The above analysis contributed towards an appreciation of the intense interplay between erosional andtectonic processes in the area and deemed drainage antecedence an important element that needs to be accounted for, in any interpretation of the origin of the twin lakes Zerelia.

scholarly journals BATHYMETRY FROM WORLDVIEW-3 SATELLITE DATA USING RADIOMETRIC BAND RATIO

2018 ◽  
Vol 58 (2) ◽  
pp. 109 ◽  
Author(s):  
Claudio Parente ◽  
Massimiliano Pepe
Keyword(s):  
Satellite Data ◽  
Specific Area ◽  
Large Area ◽  
Band Ratio ◽  
Bathymetric Data ◽  
Port Area ◽  
Satellite Sensors ◽  
Gis Environment ◽  
Short Time ◽  
The City

The use of optical satellite sensors allows to obtain bathymetry data on large area ina short time and in a cheap way. In addition, in particular places where it is difficult to carry out the survey by classic methods, the bathymetry from satellite data can be the only mode to obtain the depth of the backdrop. So, the aim of this research paper is to analyse the potential of the eight bands and the very high resolution of the commercial satellite WorldView-3 (WV-3) in order to obtain bathymetric data. Using WV-3 satellite data and the Stumpf method, the paper intends to investigate the possibility of obtaining bathymetric data in a specific area where the water is not particularly clear. To achieve this goal, in Geographic Information System (GIS) environment, several algorithms have been developed. The comparison between the results and the reference bathymetric data shows a huge potential of the WV-3 satellite data. The area of study concerns the port area of the city of Lisbon and a part of the river <em>Rio Tejo</em>, in Portugal.

scholarly journals Land Use and Land Cover Spatial Distribution in Pondicherry Coastal Region Using Remote Sensing and GIS Techniques with Special Reference to Aquaculture Development

2020 ◽  
pp. 68-81
Author(s):  
Dr. I. Raja Rajasri Pramila Devi
Keyword(s):  
Remote Sensing ◽  
Land Use ◽  
Land Cover ◽  
Coastal Region ◽  
Policy Makers ◽  
Fallow Lands ◽  
Land Cover Map ◽  
Liss Iii ◽  
Gis Environment ◽  
Development And Management

The remote sensing with GIS plays a major role in land use land cover changes. The satellite imageries of IRS 1C LISS III (1998), IRS 1D LISS III (2000) and P6 (2008 & 2014) have been used for land use and land cover map preparation. The change detection study has been carried out in a GIS environment. The results observed through many research studies have showed agriculture land was reduced from 10,968 ha to 6214.24 ha due to rapid industrialization and settlements. Pondicherry having a coastal line of 45 km also has had significant potential in fisheries. Interestingly out of 800 ha of potential fisheries area, only 138 ha of aquaculture land is utilized. Hence, commercial aquaculture can be encouraged in this area, as it should not affect the other area. It is a good economic source for local people. Moreover, the socio-economic impacts on vegetation, with settlement, plantation, aquaculture, agriculture, fallow lands and marshy lands have also been identified. The present study will be useful for policy makers towards further development and management.

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