The tidal inlets of the lagoon of moulay bousselham: operating and development
Type:
Presented during:
CEDA Dredging Days 2006 - Protection of the Coastline. Dredging and Sustainable Development, Tangiers, Morocco
Authors:
Alaoui Asmae et al.
Abstract: The lagoon of Moulay Bousselham, commonly known as Merja Zerga, is the most northern lagoon of the Moroccan Atlantic coasts. It is situated at about 120 km north of Rabat. The intervention of Man has become a determinant factor of the operating and the evolution of this eco-system. Indeed, during the closures of the inlet, its opening is operated artificially by the residents, failing which the system would evolve towards a lacustrine system that could be filled by continental inputs. On the other hand, the increasing anthropic activities become a source of considerable impact on the lagoon, in such a way that many problems are apparent today or risk popping up in the foreseeable future. This situation has prompted officials to endow this lagoon eco-system, of utmost national and international importance, with a management plan that has become a pressing need for the site.
The goal of this work is to contribute to the knowledge of the functioning of the tidal inlet zone, try to explain the mechanisms whose evolution is at stake, and to measure the creation of the system of tidal inlets vis-à-vis the anthropic action that has appreciably transformed this eco-system.
The analysis of series of air photos and multi-date topographic maps has allowed for pointing out significant information on the morpho-dynamic and granulometric mechanisms that govern this natural portion of Morocco’s north Atlantic coastline.
Indeed, highlighting an evolution cycle of the tidal inlets between 1949 and 2005 reveals the instability of the inlet, at least for the past century. It is also an artificial place that, in many times, has witnessed a total closure during this period, conditioned by three factors: (a) anthropogenic effects, (b) the energy of waves, and (c) the progradation of the terrigenous contributions, which pushed village inhabitants to step in in order to re-open it.
The tidal inlet zone requires an intervention that would ensure the permanent opening of the inlet, and thus ensure permanent exchanges between the lagoon and the ocean. These inventions should be well-measured so as to avoid any harmful impact on the eco-system.
This work is carried out part of the LagMar du REMER program, and with the support of the PAI/101/MA/04