Modelling Forest Water Use: The Forest Hydrology Information System (FHIS) (original) (raw)
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Trees have been around for more than 370 million years, and today there are about 80 thousand species of them, occupying 3.5 billion hectares worldwide, including 250 million ha of commercial plantations. While forests can provide tremendous environmental, social, and economic benefits to nations, they also affect the hydrologic cycle in different ways. As the demand for water grows and local precipitation patterns change due to global warming, plantation forestry has encountered an increasing number of water-related conflicts worldwide. This document provides a country-by-country summary of the current state of knowledge on the relationship between forest management and water resources. Based on available research publications, the Editor-in-Chief of this document contacted local scientists from countries where the impact of forest management on water resources is an issue, inviting them to submit a chapter.
T 2 0 0 7 Plantations and Water Use
2007
The effects on runoff of land cover change such as reforestation depend on the proportion of the catchment affected. Because rainfall and hydrological factors are highly variable, in small catchments it is difficult to measure an impact if reforestation is less than 15-20% of total catchment area. This threshold is lower in larger catchments. Stream flow from small sub-catchments may become more intermittent if a large proportion is reforested. The plantation forestry industry reports that it is aiming to increase the plantation area in the headwater catchments of the Murray Darling Basin by a total of less than 50,000 hectares by 2020. Studies of two catchments in that region indicate that such forecast plantation expansion may reduce stream flow by up to about 1%. At a local scale, and in particular years, the impact may be significant if new plantations are concentrated in particular subcatchments.
Forest Plantations and Water Consumption: A Strategy for Hydrosolidarity
International Journal of Forestry Research, 2012
A case study of a deliberate change in the design of a new Eucalyptus plantation, aimed at alleviating water impacts, was carried out in an experimental catchment located in the center part of the State of São Paulo, Brazil. It involved the identification of saturated areas in the catchment, based essentially on topographic analysis, as a tool to help in zoning of the new forest plantation, with the objective of improving the flow of water to downstream users, as well as to avoid water quality changes. The design involved the allocation of part of the identified saturated areas as water conservation areas, as well as a change in the spacing of the planting. Measurements of tree growth at the age of two years of the new plantation reveal that the forest productivity of the new plantation design, in terms of projected annual wood increment at the end of the rotation, will be similar to the old plantation scheme, despite the loss of planted area. Preliminary results of the continuous m...