@article{fdi:010090795,
  title = {{W}ater mass circulation and residence time using {E}ulerian approach in a large coastal lagoon ({N}okou{\'e} {L}agoon, {B}enin, {W}est {A}frica)},
  author = {{H}onfo, {K}. {J}. and {C}haigneau, {A}lexis and {M}orel, {Y}. and {D}uhaut, {T}. and {M}arsaleix, {P}. and {O}kpeitcha, {O}. {V}. and {S}tieglitz, {T}homas and {O}uillon, {S}ylvain and {B}aloitcha, {E}. and {R}{\'e}tif, {F}.},
  editor = {},
  language = {{ENG}},
  abstract = {{S}easonal water circulation and residence times in the large (150 km2) and shallow (1.3 m average dry season depth) {N}okou{\'e} {L}agoon ({B}enin) are analyzed by means of numerical simulations using the three-dimensional {SYMPHONIE} model. {T}he average circulation during the four primary hydrological periods throughout the year are studied in detail. {D}espite the lagoon's shallowness, significant disparities between surface and bottom conditions are observed. {D}uring the flood season ({S}eptember-{N}ovember), substantial river inflow (-1200 m3/s) leads to nearly barotropic currents (-7 cm/s), 'directly' linking rivers to the {A}tlantic {O}cean. {R}apid flushing results in short water residence times ranging from 3 to 16 days, with freshwater inflow and winds driving lagoon dynamics. {D}uring the salinization period ({D}ecember-{J}anuary) the circulation transforms into an estuarine pattern, characterized by surface water exiting and oceanic water entering the lagoon at the bottom. {A}verage currents (-2 cm/s) and recirculation cells are relatively weak, resulting in a prolonged residence time of approximately 4 months. {C}irculation during this time is dominated by tides, the ocean-lagoon salinity gradient, wind, and river discharge (-100 m3/s). {D}uring low-water months ({F}ebruary to {J}une), minimal river inflow and low lagoon water-levels prevail. {P}redominant southwest winds generate a small-scale circulation (-3 cm/s) with a complex pattern of multiple recirculation and retention cells. {R}esidence times vary from 1 to 4 months, declining from {F}ebruary to {J}une. {D}uring the lagoon's desalination season ({J}uly-{A}ugust), increasing river inflows again establish a direct river-ocean connection, and average residence times reduce to -20 days. {N}otably, a critical river discharge threshold (-50-100 m3/s) is identified, beyond which the lagoon empties within days. {T}his study highlights how wind-driven circulation between {D}ecember and {J}une can trap water along with potential pollutants, while river inflows, tides, and the ocean-lagoon salinity gradient facilitate water discharge. {A}dditionally, it explores the differences between residence and flushing times, as well as some of the limitations identified in the simulations used.},
  keywords = {{L}agoon circulation ; {R}esidence time ; {N}okou{\'e} {L}agoon ; {N}umerical modelling ; {F}orcings ; {BENIN} ; {ATLANTIQUE}},
  booktitle = {},
  journal = {{O}cean {M}odelling},
  volume = {190},
  numero = {},
  pages = {102388 [17 p.]},
  ISSN = {1463-5003},
  year = {2024},
  DOI = {10.1016/j.ocemod.2024.102388},
  URL = {https://www.documentation.ird.fr/hor/fdi:010090795},
}