Modelling the Loire River and its estuary
Understanding the complexity of the river’s environmental functioning
CONTEXT & ISSUES
The result of an initiative launched in 1998, the GIP Loire Estuaire carries out a series of operations to improve understanding and enable enlightened governance of this river. It carries out operations to acquire, exchange, promote and disseminate environmental data, by coordinating a network of partners. The objective is to build up and share expertise on the Loire Estuary.
Artelia has recently been involved in the development of a 3D hydrosedimentary and water quality model of the river estuary, comprising 3 complementary models. This is an operational tool needed to support a number of projects in the region: the impact of morphological changes in the river on environmental functioning and uses, the effects of climate change, research projects, etc. The Loire carries sediment, which is concentrated in the estuary, where the river meets the sea. This area, loaded with suspended matter, forms a muddy plug, a key phenomenon in understanding the river, which changes with the rhythm of the tides and the river’s flow.
Calibrated for the 2018-2019 hydrological year, for which numerous in situ measurements were available, this model has already been used for a number of projects. In particular, during the low-water months, it has been used to assess the concentrations of suspended solids at the Mauves-sur-Loire drinking water intake, which supplies the whole of the Nantes metropolitan area. It has also been used to analyse certain port projects, including the impact of dredging on dissolved oxygen concentrations, whether carried out by stationary suction dredger (DAS) or water injection dredger (DIE).