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A mass-balance approach to estimate in-stream processes in a large river

Teissier, Samuel and Sauvage, Sabine and Vervier, Philippe and Garabétian, Frédéric and Sanchez-Pérez, José-Miguel A mass-balance approach to estimate in-stream processes in a large river. (2008) Hydrological Processes, vol. 2 (n°3). pp. 420-428. ISSN 0885-6087

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Official URL: http://dx.doi.org/10.1002/hyp.6614

Abstract

A mass-balance approach was used to estimate in-stream processes related to inorganic nitrogen species (NH4 C, NO2 and NO3 ) in a large river characterized by highly variable hydrological conditions, the Garonne River (south-west France). Studies were conducted in two consecutive reaches of 30 km located downstream of the Toulouse agglomeration (population 760 000, seventh order), impacted by modification of discharge regime and high nitrogen concentrations. The mass-balance was calculated by two methods: the first is based on a variable residence time (VRT) simulated by a one-dimensional (1-D) hydraulic model; the second is a based on a calculation using constant residence time (CRT) evaluated according to hydrographic peaks. In the context of the study, removal of dissolved inorganic nitrogen (DIN) for a reach of 30 km is underestimated by 11% with the CRT method. In sub-reaches, the discrepancy between the two methods led to a 50% overestimation of DIN removal in the upper reach (13 km) and a 43% underestimation in the lower reach (17 km) using the CRT method. The study highlights the importance of residence time determination when using modelling approaches in the assessment of whole stream processes in short-duration mass-balance for a large river under variable hydrological conditions.

Item Type:Article
Additional Information:Thanks to John Wiley & Sons publisher. The definitive version is available at www3.interscience.wiley.com
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By:Florence Amor

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