Silting up

Piles of earth, sand, gravel, pebbles brought by water and created by a decrease in flow velocity. This phenomenon is generated by the plant growth cycle that brings every year a litter layer (up to several tons per year). Much of this litter is very slowly changed into mineral salts by bacteria and microscopic fungi. Sediment inputs and vegetable deposits from outside add to the filling of the marsh thus acting as a biogeochemical buffer for the drainage basins.