Water balance of forested catchments:
More than 26% of the land surface are covered by forests. Today these forests are threatened by human activities like increasing usage of wood, agricultural use and air pollution. The water budget of forested catchments differs markedly from bare soils or grasslands by significantly higher interception losses due to higher leaf area per surface area.
This filtering function of forests leads generally to a lower quantity but better quality of usable water as well as to a more equally distributed runoff thus minimising erosion. In the last decades the contamination of vegetation and soils by high deposition led to a higher concentration of nitrogen in runoff, especially near strong emissions. Altogether the positive effects of forested watersheds on water supply dominate, so that the conservation of large and dense forests is necessary to cope with global water problems in the future.