Riparian Vegetation Management: Reconciling Environmental and Anthropogenic Issues

摘要

Historically, people lived in harmony with watercourses, cultivating their land and creating their habitat according to the benefits and the whims of the rivers. Since the beginning of the 20th century, man has domesticated his environment with determination. The rural exodus, the agricultural depreciation and the numerous river amenities have resulted in a momentum of area closures and in the modification of hydraulic conditions during the flow of flood waters. An unmanaged vegetation colonization along the edge of watercourses (protection dikes, retention dams, appointed river banks) induces various issues; however, a drastic management is not absolutely beneficial and sometimes even runs counter to the objective. The environmental issues conciliation – positive impact on fluvial ecosystems (shade, water decontamination, bank stabilization, biodiversity) – with anthropogenic issues is therefore essential to identify these suitable management solutions. Since 1970 and until 2006, phytopharmaceutical products were used extensively to control vegetation development on dikes, dams and canals due to their high-speed action and their low-cost implementation. Phytopharmaceutical product prohibition induces a great expansion of vegetation on structure cladding. Pioneer trees species like poplar are largely represented. Implanted near water points they grow fast in phytopharmaceutical treatment prohibited zone. Woody vegetation control methods are frequently implemented too late, when impacts caused by roots are observed; structural reparation costs are consequently very high. New vegetation management solutions have to be developed, in order to allow both risk reduction and environmental preservation. Some different eco-friendly solutions exist but must be promoted by rivers and dikes managers. This paper presents these integrated solutions and illustrates through some case studies the implemented solutions to reconcile the antagonist environmental and anthropogenic issues.