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

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.

An Integrated Environmental Assessment of a coastal lagoon: The Case of the Oualidia lagoon (Morocco)

This paper aims to present a comprehensive socio-economic and environmental analysis of the Oualidia lagoon in Morocco. This lagoon is classified as a RAMSAR site since 2005, providing valuable ecosystem services for the surrounding population. This paper followed the Drivers-Activities-Pressures-State-Change-Impact-Responses (DPSIR) framework to evaluate environmental condition changes within the lagoon to support decision-making. The present research suggests a potential future model for safeguarding the lagoon's ecosystem without risking the well-being of future generations.

The value of carbon sequestration and storage in coastal habitats areas in North West of Morocco

Morocco, like the rest of the world, is experiencing a climate change that threatens a number of wetlands. Marine ecosystems contribute to the regulation of the Earth’s climate, but their degradation releases large quantities of greenhouse gases (GHGs) such as carbon dioxide (CO2) into the atmosphere. This paper aimed to map and model changes in carbon storage and sequestration for coastal habitats using the INVEST model, using the Sidi Moussa-Oualidia lagoon complex as a case study. To achieve this objective, several data were used, namely, land use and land cover maps between 2003 and 2020, as well as data on the amount of carbon stored in the three basins; biomass, sediment carbon (soil) and dead carbon (litter), and the annual rate of carbon accumulation in biomass and sediment. The results obtained in this work allowed us to compare the two former and current carbon stock and net sequestration scenarios and to evaluate the social cost of carbon in the study area. This study can facilitate the development of a coastal rehabilitation strategy to take advantage of the benefits of these wetlands and, at the same time, to conserve the ecosystem services provided by these environments, including the CBCS.