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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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Bureau for Economic Theory and Applications

Laboratoire d'Economie Forestière

Forest and water

Valuation of the environmental service provided by the forest for water quality

  • Summary

Our work on the forest for water was initiated by the joint action INRA and CNPF-IDF "Forest and water" in 2006.
A LEF team has developed a new approach to estimate the economic value of the water protection and purification service from forests. We assume that if land use affects the quality of raw water, then this impact can be quantified through the costs of drinking water supply services. Nitrate surveys under wheat crops indicate concentrations 20 times higher than in forested areas. This figure rises up to 60 times for corn fodder. Similar results are found for other pollutants such as pesticides. Our approach is based on the estimation of drinking water supply costs in which the relationships with land uses are explicitly modeled, while taking into account a number of controls characterizing drinking water supply services . Changes in cost or price of water make it possible to identify the value associated with the benefits of the forest relative to other land uses.

  • Involved Researchers

Person in charge of the project: Serge Garcia

Other researchers: Jens Abildtrup, Anne Stenger

  • Results

The work of Fiquepron et al. (2013) seeks to quantify the impact of forests on the quality of raw water with respect to other land uses. Based on measurements of quality parameters that have been identified as the most problematic (e.g., pesticides and nitrates), we have modeled how water quality was influenced by different land uses. In order to evaluate the benefits of the forest in monetary terms for the improvement of water quality, we use drinking water prices determined by the operating costs of water supply services. This first valuation exercise is realised at the scale of France from the data collected in each administrative department. We have designed and estimated a model that describes the impact of land use on water quality, the operation of drinking water services and prices. We show that the forest has a positive effect on the quality of raw water compared to other land uses, with an indirect impact on water prices, lower for consumers. This effect on the price is low, but would represent a potential savings of almost 12 million euros per year for French consumers. We find that afforestation of one hectare would save about €22 per year on household water bills.
In the study by Abildtrup et al. 2013, a cost model is estimated taking into account the impact of land uses on raw water, the spatial scale of the ecological process and spatial interactions between water services. The econometric application is carried out on a sample of water services in the department of Vosges in France. When one hectare of agricultural land is replaced by one hectare of forest, the ecological service provided by the forest reaches values ​​of up to €140/ha/year.
In abildtrup et al. 2015, we estimated a model with two regimes to account for the interactions between the management mode (public or delegated management) and water prices. This model also permits spatial interactions between water utilities and omitted spatial explanatory variables. The results confirm that forest cover reduces the price of drinking water and that spatial factors influence the choice of management mode and water prices.

  • List of publications
  1. Abildtrup J., Garcia S., Kéré E. (2015). "Land use and drinking water supply: A sample selection model with spatial dependence", Revue d’Économie Régionale et Urbaine, 1/2015 (mai), 321-342.
  2. Abildtrup, J., Garcia S., Stenger A. (2013). “The effect of forest land use on the cost of drinking water supply: A spatial econometric analysis”, Ecological Economics, 92, 126-136.
  3. Fiquepron J., Garcia S., Stenger A. (2013). “Land use impact on water quality: Valuing forest services in terms of the water supply sector”, Journal of Environmental Management, 126, 113-121.
  • Work in progress

See also the actions of the private forest on water:

Serge Garcia et Jens Abildtrup (substitute) are involved in the COST Action PESFOR-W: