PRINCIPAUX ENJEUX ET PROPOSITIONS POUR UNE GESTION ET UNE PROTECTION HARMONIEUSES DES RESSOURCES EAU ET BOIS

Among the various environmental functions exercised by forests, protection of water resources deserves special attention to which several recent projects have contributed. Because forest cover is continuous, the intense biological activity of forest soils, silvicultural practices involving few chemical inputs, the water coming from forest-covered watersheds is of higher quality than that coming from other types of land use and at a low cost. Forestry activities may however generate localised or diffuse contaminations that should be prevented for which technical solutions are well known. However, procedures concerning the protection of catchment areas prove difficult to implement. Another financial incentive based on contract is currently being investigated. In quantitative terms, forests very significantly influence rainfall patterns, with two antagonistic effects: indeed, the forests reduces run-off and are conducive to water seepage into the aquifers, but they nonetheless intercept and transpire a significant portion of that rainfall. Depending on the architecture of forests and catchment areas, the overall quantitative balance, compared to other types of land uses, may be a surplus or a deficit in terms of the water resource. The digital modelling tool developed under the LIFE+ SEMEAU project provides a means of measuring this quantitative role of forests together with some qualitative effects (nitrates). This integrated approach has enable the Société des Eaux de Volvic to supplement its water protection policy in partnership with all the forest players in the catchment area. This project opens up prospects for technical improvement of “hydrological productivity” of forests. In areas subjected to heavy demographic or climatic pressures, this opportunity for mitigating tensions relating to the water resource is an additional goal for forest management. In this regard, it is desirable to review the funding mechanisms for water management so as to move them away from the generally curative measures and more towards the virtuous promotion of environmental amenities Parmi les diverses fonctions environnementales exercées par la forêt, la protection de la ressource en eau mérite une attention particulière, que plusieurs projets récents ont permis de nourrir. Grâce à la pérennité du couvert, la forte activité biologique des sols forestiers, des pratiques sylvicoles peu consommatrices d’intrants chimiques, l’eau issue des bassins versants forestiers présente,