Hydromorphology

Is defined by opposition to the ridge line (or "topographic divide" or "watershed"). The space between two thalwegs is called "interfluve". Bottom line of a valley. In a drained valley, the thalweg is the bed of the watercourse.

Ratio between the developed river length in a valley and the length of the valley itself.

Structure located in the minor bed of a watercourse to fill an excessive bed depression caused by the extraction of materials or by a structure for example. It can be a low structure normally submerged, built for various purposes, possibly to stabilize the water level/flow rate ratio in a stream at a station, or the top of a dike or of any other structure, or of a natural levee, on which water can flow when it reaches a sufficient level.

Modification and homogenization of the longitudinal profile of the river (slope), always to increase its discharge capacity. Reshaping consists in equalizing the slope of the stream, changing the zoning of the longitudinal profile. This operation requires the removal of riparian vegetation and

Horizontal realignment of the watercourse (shortening a portion of a meandering stream) to increase its discharge capacity by increasing flow velocity.

Profile that characterizes the slope of the watercourse or more generally the thalweg. This slope tends to decrease downstream (concave profile) and different river features are succeeding from upstream to downstream.

Longitudinal profile of a river whose erosive power is not sufficient.

Operation for raising awareness, for the protection or appropriate management of lands threatened by latent human pressure. This can be achieved by biotope protection orders, the purchase of lands on an extended alluvial plain or in a potential river mobility area, contracts with farmers for extensive farming on riparian lands, the definition of "buffer" zones, etc.

An area of a river floodplain. The meadows liable to flooding are rich areas from a biological standpoint, many protected animal or plant species being found there. Depending on the richness of the soil and waterlogging duration, the hedge hyssop, the fritillaria meleagris or snake's head, protected species in France, are blooming. The flora is often accompanied by an animal population composed of amphibians, small mammals and especially many insects. Among the latter, butterflies of high value to biodiversity, such as the marsh fritillary, the Alcon blue and large copper, or grasshoppers such as the Stethophyma grossum…