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Pollution source identification : theory and application

English title Pollution source identification : theory and application
Applicant Perrochet Pierre
Number 124492
Funding scheme Project funding (Div. I-III)
Research institution Centre d'hydrogéologie et de géothermie Université de Neuchâtel
Institution of higher education University of Neuchatel - NE
Main discipline Geology
Start/End 01.02.2010 - 31.01.2013
Approved amount 174'282.00
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All Disciplines (2)

Discipline
Geology
Other disciplines of Earth Sciences

Keywords (6)

Pollution source identification; Groundwater contamination modelling; Backward transport; Location probability; aquifer contamination; numerical simulation

Lay Summary (English)

Lead
Lay summary
An important issue in any remediation process of polluted groundwater is the assessment of groundwater contamination. This requires not only understanding of the dynamics of the aquifer system in which the contamination is propagating but also identification of unknown contamination sources and release histories that led to pollution. This is important both for the design of adequate remedial measures and to assign responsibilities.Many mathematical methods have been developed to deal with the identification of unknown pollution sources and contamination times, but all of them are subject to significant drawbacks and limitations, such as parameter homogeneity, simple flow geometries, high sensitivity to noise, previous knowledge of potential source locations and/or contamination time and history, or excessive computational effort.Recently, Milnes & Perrochet (2007) and Perrochet & Milnes (2008) developed an original simulation procedure based on the transfer function theory (e.g., Jury & Roth 1990) to identify both the unknown point-source location and contamination time with a single reversed flow field simulation. Although this new approach is seductive due to its simplicity, it is still bound to severe restrictions, such as perfectly known flow field conditions, conservative contaminants and known initial contaminant mass input. The present research proposal aims at extending and adapting the developed theoretical framework to alleviate these restrictive assumptions and to render the approach applicable to realistic contamination configurations. For that reason the research plan is subdivided into a theoretical and a practical work package, which partially overlap. The focus will first be put on theoretical developments to simulate cases where only few observation points are known and the contamination mass is unknown, where several point-sources pollution plumes are superimposed, where the contaminant is reactive and the flow field conditions are uncertain. Then, to evaluate and test the applicability of the developed simulation procedures, cross-validation will be done on real case sites: i) on historical data from the well-documented natural gradient tracer test in the Borden sand aquifer in Canada (Sudicky 1986), ii) on the Zürich-Affoltern gasoil accident in 1994 which has been monitored over the past decade (Munz et al. 2005), and iii) on specifically designed tracer tests that will be carried out in the Seeland test site in Switzerland.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
105196 Beyond Advective-Dispersive Transport in Aquifers: Probabilistic Flow Systems and their Time-Space Variability 01.10.2004 Project funding (Div. I-III)
64927 Beyond Advective-Dispersive Transport in Aquifers: Generalizing Reservoir Theory to Probabilistic Flow Systems 01.10.2001 Project funding (Div. I-III)
110374 Groundwater salinisation by irrigation return flow and solute recycling in semi-arid regions: development of a numerical risk assessment tool and field validation 01.01.2006 Fellowships for prospective researchers

Abstract

An important issue in any remediation process of polluted groundwater is the assessment of groundwater contamination. This requires not only understanding of the dynamics of the aquifer system in which the contamination is propagating but also identification of unknown contamination sources and release histories that led to pollution. This is important both for the design of adequate remedial measures and to assign responsibilities.Many mathematical methods have been developed to deal with the identification of unknown pollution sources and contamination times, but all of them are subject to significant drawbacks and limitations, such as parameter homogeneity, simple flow geometries, high sensitivity to noise, previous knowledge of potential source locations and/or contamination time and history, or excessive computational effort. Recently, Milnes & Perrochet (2007) (see attached paper) developed an original simulation procedure based on the transfer function theory to identify both the unknown point-source location and contamination time with a single reversed flow field simulation. Although this new approach is seductive due to its simplicity, it is still bound to severe restrictions, such as perfectly known flow field conditions, conservative contaminants and known initial contaminant mass input.The present research proposal aims at extending and adapting the developed theoretical framework to alleviate these restrictive assumptions and to render the approach applicable to realistic contamination configurations. For that reason the research plan is subdivided into a theoretical and a practical work package, which partially overlap.The focus will first be put on theoretical developments to simulate cases where only few observation points are known and the contamination mass is unknown, where several point-source pollution plumes are superimposed, where the contaminant is reactive and the flow field conditions are uncertain. Then, to evaluate and test the applicability of the developed simulation procedures, cross-validation will be done on real case sites: i) on historical data from the well-documented natural gradient tracer test in the Borden sand aquifer in Ontario, ii) on the Zürich-Affoltern gasoil accident in 1994 which has been monitored over the past decade, and iii) on specifically designed tracer tests that will be carried out in the Seeland test site in Switzerland.
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