Publication de 4 numéros par an
ISSN Imprimer: 2151-4798
ISSN En ligne: 2151-562X
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ESTIMATION OF CONTAMINANT SPREAD IN A TWO-LAYER AQUIFER FOR RECHARGE AND WITHDRAWAL SCENARIOS USING THE METHOD OF MOMENTS
RÉSUMÉ
Contaminant dispersion in a two-layer aquifer system has been investigated for recharge and withdrawal conditions in which both the layers are connected through two finite strips of pervious interfaces. The upper layer is considered as a dumping ground for reactive contaminant whereas the lower layer has a reactive bed that is initially free from contamination. Using an Alternate Direction Implicit (ADI) scheme, layer-wise advection-diffusion coupled equations have been solved. We employed the method of moments to study time evolution of contaminant plume for two specific scenarios: withdrawal and recharge from a rectangular well, positioned at the surface of upper layer. After obtaining the gridwise computed concentration values up to a period of 10 years, an Edgeworth asymptotic series was employed. The gross behavior of contaminant plume was analyzed through mean concentration distribution and centroid displacement. The deviation of mean concentration distribution from Gaussianity was also examined by means of skewness and excess coefficient. Simulations were carried out for layer wise varying Péclet number (Pe) which lies between 1 and 20. The model result shows enhanced contaminant dispersion in lower layer for recharge as well as withdrawal conditions, despite first-order chemical reaction at the bed boundary.