Forest hydrology

Forest hydrology

Forest hydrology is a discipline that deals with interactions between forests and the water cycle. Forest hydrology provides useful information for the much-needed efforts to maintain and restore water-related ecosystems.

Forests influence the amount of water that is readily available in an ecosystem for uptake by organisms by intercepting precipitation in its various forms (including fog water) and capturing transpiration of soil moisture and evaporation from vegetative surfaces. By maintaining (or improving) soil infiltration and soil-water storage capacity, forests influence the timing of water delivery, minimize erosion, and decrease downstream sedimentation.

In watersheds, upstream forests buffer water bodies and watercourses by trapping sediments and deleterious pollutants from other up-slope land uses and activities. Riparian forests running alongside watercourses are also effective buffer zones that stabilize stream banks, maintain cool water tempertures and input organic material important for wildlife habitat.

The relationships between forests and water have not been fully understood in the past. Recent research in forest hydrology has challenged common wisdom and many assumptions and also the policies that were based on them. As part of the Forest Resources Assessment (FRA) 2005, the Forests and Water Programme conducted a review of the current knowledge about the interactions between forests and water in different forestry situations. This review resulted in a publication of the FAO Forestry Paper series: Forestry Paper No. 155 "Forests and water".