Numerical modelling of transport time scales within Nador lagoon (Morocco)

Alistair Borthwick, Mohammed Jeyar, Elmiloud Chaabelasri, Najim Salhi, Imad Elmahi

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The intrinsic cleaning capacity of semi-enclosed hydrodynamic basins can be controlled by the time spent by each water particle inside it, giving an idea of the efficiency of this cleaning process. However, the determination of water residence time, and/or water exposure time, is thus of major interest in the environmental management. In this paper, an integrated 2D depth-averaged hydrodynamic dispersion model is used to simulate the time scales of tracer transport processes within Nador lagoon, Morocco, for various tidal forcing
conditions. Tidal hydrodynamics are predicted using a finite volume solver of the shallow water equations on an unstructured triangular mesh fitted to the lagoon geometry. Tracer dispersion is predicted by solving the Eulerian advection-diffusion equation. Residence and exposure times are determined from the remnant function obtained from the concentration of passive tracers released inside the lagoon. Numerical simulations covering spring and neap tidal cycles are used to investigate the influence of tidal forcing on residence and exposure
times in sub-basins of the Nador lagoon, from which overall mean values of the time scales are estimated for the entire lagoon allowing for the return flow factor of the basin. The results demonstrate the importance of tidal cycles on transport time scales and self-cleansing of the Nador lagoon; for example, it is found that
self-cleansing takes about 1 day longer at neap tide than at spring tide.
Original languageEnglish
JournalWorld Journal of Modelling and Simulation
Volume13
Issue number2
Publication statusPublished - May 2017

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