Contribution à l’Etude du Fonctionnement Hydrologique de l’estuaire de Mafragh (Nord-Est d’Algerie)
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Date
2015-06-13
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Université Abbes Laghrour -Khenchela-
Abstract
Abstract
The estuarine system of the Mafragh represents a singular coastal zone in the
Mediterranean by its diversity of habitats including marsh, swamp, rivers, estuary, flooded
plains and coastal dunes. The estuary exchanges daily with the sea 10-30 Millions m
of
freshwater loaded in nutriments, sediments, organic matters, plankton and contributes to
fertilizing the adjacent littoral area. The objective is to determine the hydrological conditions
of the estuarine system. The hydrological parameters have been surveyed in 19 stations of the
estuarine system. The stations have been sampled during four seasonal cruses (winter, spring,
summer and autumn 2006. During the year, the estuary experienced three distinct phases:
river, estuarine and lagoon. In winter, the estuary functions as a core river flowing at the sea
with strong amounts preventing the marine intrusion. In spring, the river is affected by a semidiurnal
tide conferring it an estuarine character with salt wedge, functioning according to a
double layer system, strongly stratified. In estuarine phase, the salt-wedge occupies 80% of
the water column and penetrates until 20km in the El-Kébir branch and 15km in the
Bounamoussa tributary. In closing period, in summer and in autumn, the stratification
disappears and the whole layer becomes well-mixed in the lagoon phase. According to the
phase, waters are oligohalin in winter, mésohalin in the spring and méso-polyhalin in summer
and in autumn.