Benthic quality evaluation of immersion zones of sediments dredging

Résumé

Dredging operations pose the problem of sediment deposits to be evacuated by taking into account economic incidences and environmental aspects related to environmental protection. Coastal sediments are high biodiversity zones, where a multitude of living organisms have a special relationship with their substrate. An addition of exogenous materials has an impact on the natural equilibrium of the environment, notably during the transfer of contaminants on immersion zones, affecting species and the ecosystem. The objective of environmental assessment process is to estimate the potential risk of exposure upon ecosystems by integrating the benthic communities assessment. The evaluation of biological impacts in immersion zones helps to apprehend better the risk of using operational tools of appreciation. The aim of this paper is to present an expertise approach based upon index for assessing coastal endofauna. This index makes it possible to know sediment biological quality by making more transparent the environmental assessment process potentially influencing the deposits method and the monitoring of dredging operations in a sustainable development context. Study results show that sediments immersion effect is low and has a short duration on immersion zones having strong currents allowing rapid sediments resuspension.

Version traduite : Evaluation de la qualité benthique des zones d’immersion des sédiments de dragage