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The programme > Objectives > River dynamics

RIVER DYNAMICS


The Loire and the Allier are certainly among the most beautiful examples of dynamic water courses in Western Europe. In the alluvial plains, the river dissipates its energy by removing alluvion from the banks and river bed and depositing it on the opposite side. With passing seasons, the meander thus formed grows until, during a flood, the force of the river creates a shortcut across the meander, leaving behind a bow-shaped abandoned channel, an oxbow lake. It is this natural result of river dynamics which creates a constantly evolving environmental mosaic, responsible for the diversity of habitats. The environments thus formed, from dry beach meadows to alluvial forests via wetland vegetation along abandoned channels, all make these alluvial zones areas of great natural value to our heritage. The banks provide reproductive sites for the Bank swallow. Sands and eroded pebbles are then deposited downstream and are used by the European Stone curlew. Further on, water meadows, maintained by grazing, are found beside alluvial forests where the Beaver lives. Old meanders abandoned temporarily by the rivers, known as oxbows, particularly host the European pond turtle. By extracting huge quantities of sand and gravel from rivers and installing rock armouring to protect the banks from erosion, human intervention has deeply disturbed river dynamics, leading to deepening of the river bed (from one metre to 3.5 m) with serious consequences for ecological functions as well as for users of the rivers and their wealth. To conserve river dynamics, the river must have a free zone, meaning a preserved area where the river retains its natural path. For this purpose, Loire nature operators have purchased land in actively eroding zones in order to let the various phenomena take place and avoid the use of rock armouring.


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