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Polluted site assessment using Inverse Distance Weighted and Ordinary Kriging: advantages and limitations.
2009 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Precise and accurate delineation of polluted sites is an important stake among soil remediation professionals. Information available for estimation is often incomplete and/or heterogeneous. That usually leads to the discovery of unexpected polluted volumes during remediation phase and costs overrun. On the opposite, certain projects may be wrongly judged too expensive due to an overestimation of the pollution. Different tools are used today in order to estimate pollution as accurately as possible. Though, the spatial variability of the pollution, if not reproduced properly, induces unrealistic contamination delineation. Consequently a model appropriate to the concerned site is necessary to evaluate the pollution consistently. To give solutions to these issues, this master thesis considered the use of Inverse Distance Weighted (IDW) and Ordinary Kriging (OK) in order to estimate two polluted sites in Norrbotten, Sweden: Solgårdarna and Tväråns såg area. Both methods can not be applied without hypotheses verification, as the second order stationarity of data for OK: the estimation method should therefore be chosen regarding the specificities of the site and their adequacy to these hypotheses. It has been shown that some method parameters such as the power or the search neighbourhood ellipsoid of IDW have a non negligible impact on results (more than 20%) and should be chosen carefully. Also transformation of data helps to make them more stable reducing the impact of outliers but, if not applied properly, may lead to results different of more than 45%. The different methods have been compared by cross-validation. Limitations of the cross-validation method have been examined.

Place, publisher, year, edition, pages
Keyword [en]
Life Earth Science, polluted soils, remediation, assessment, Inverse Distance, Weighted, neighborhood search ellipsoid, power, geostatistics, Ordinary Kriging, semi-variogram, cross, validation
Keyword [sv]
Bio- och geovetenskaper
URN: urn:nbn:se:ltu:diva-46899ISRN: LTU-PB-EX--09/026--SELocal ID: 48166ba7-2a44-4116-a274-f649a2b14b63OAI: diva2:1020215
Subject / course
Student thesis, at least 30 credits
Educational program
Geosciences, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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