External Phosphorus Load Estimates and P-Budget for the Hydroelectric Reservoir of Bort-les-Orgues, France

Authors: Brigault S.¹; Ruban V.²

Source: Water, Air, and Soil Pollution, Volume 119, Numbers 1-4, April 2000 , pp. 91-103(13)

Publisher: Springer

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Abstract:

This paper presents two methods used to estimate the external phosphorus load for the hydroelectric reservoir of Bort-Les-Orgues (in France's `Massif Central' region). The P load calculated from export coefficients (150 t yr^-1) agreed with field measurements taken during a one-year survey carried out from March 1996 to February 1997 (121 t yr^-1). Export coefficients represent a good option for estimating phosphorus loads of other reservoirs in the region of Bort-Les-Orgues, provided that they display similar characteristics. These external load estimates are greater than the maximum permissible load for a mesotrophic lake calculated from the OECD equations (40 t yr^-1); thus, a yearly reduction of about 60 t should ideally be achieved. This target, however, is probably too ambitious, and measures to reduce both point and non-point sources must be implemented for the reservoir to tbe mesotrophic. Moreover, Bort-Les-Orgues is a tourist area. As such, the presence of algal blooms (a regular occurrence on the lake) due to an excess of P in the lake's water inflow could actually exert a negative impact on regional economy.

Keywords: eutrophication; external load; mass balance; P-export coefficient; phosphorus; reservoir

Language: English

Document Type: Regular paper

Affiliations: 1: Laboratoire Central des Ponts et Chaussées, BP 19, 44340 Bouguenais, France 2: Laboratoire Central des Ponts et Chaussées, BP 19, 44340 Bouguenais, France (author for correspondence, e-mail: veronique.ruban@lcpc.fr; fax: +33 2 40845998)

Publication date: 2000-04-01