According to Agenda 21, natural resources are any product that man uses and that exists in nature: water, earth, minerals, plants, animals, air, sun, etc. The exploitation of natural resources must contribute in the long term to the improvement of living conditions with a view to socio-economic and cultural development. The exploitation of natural resources must contribute in the long term to the improvement of living conditions with a view to socio-economic and cultural development. Sustainable development must therefore contribute to protecting and rehabilitating existing potential, with a view to the rational use of biological diversity. The issue of natural resource management in general, and riverbank protection in particular, therefore arises in terms of adapting the techniques and approaches used to exploit and manage these resources. It is no longer a question of preserving biodiversity as a resource 'in itself', but of increasing it and making it available to meet the needs of current and future populations.