Documents disponibles écrits par cet auteur

Comparison of field data and water-balance predictions for a capillary barrier cover / A. S. Ogorzalek in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°4 (Avril 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°4 (Avril 2008) . - pp. 470–486 Titre : Comparison of field data and water-balance predictions for a capillary barrier cover Type de document : texte imprimé Auteurs : A. S. Ogorzalek, Auteur ; G. L. Bohnhoff, Auteur ; C. D. Shackelford, Auteur Année de publication : 2008 Article en page(s) : pp. 470–486 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Unsaturated  flow  Water  balance  Coverings  Barriers  Containment Résumé : Predictions of surface runoff (R) , evapotranspiration (ET), soil–water storage (S) , and percolation obtained using three numerical codes (LEACHM, HYDRUS, and UNSAT-H) employed to simulate the hydrology of water-balance covers are compared to measured water-balance data from a lysimeter used to monitor a capillary barrier cover profile in a subhumid climate. All of the codes captured the seasonal variations in water-balance quantities observed in the field. LEACHM and HYDRUS predicted total R during the monitoring period with reasonable accuracy (within 18mm using general mean parameters), but the timing of predicted and observed R events was different. In contrast, UNSAT-H consistently overpredicted R by at least 239mm . Evapotranspiration was predicted reliably (within 60mm ) with all three codes when data from the first year were excluded. However, all three codes overpredicted ET in late winter and early spring, when snowmelt was occurring and S was accumulating in the field. Consequently, S generally was underpredicted by all three codes. Predicted and measured percolation were in good agreement (within 1mm∕year ), except during the first year. Results of the comparison indicate that cover modelers should scrutinize runoff predictions for reasonableness and carefully account for snow accumulation, snow melt, and ET during snow cover. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A4%2847 [...] [article] Comparison of field data and water-balance predictions for a capillary barrier cover [texte imprimé] / A. S. Ogorzalek, Auteur ; G. L. Bohnhoff, Auteur ; C. D. Shackelford, Auteur . - 2008 . - pp. 470–486. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°4 (Avril 2008) . - pp. 470–486 Mots-clés : Unsaturated  flow  Water  balance  Coverings  Barriers  Containment Résumé : Predictions of surface runoff (R) , evapotranspiration (ET), soil–water storage (S) , and percolation obtained using three numerical codes (LEACHM, HYDRUS, and UNSAT-H) employed to simulate the hydrology of water-balance covers are compared to measured water-balance data from a lysimeter used to monitor a capillary barrier cover profile in a subhumid climate. All of the codes captured the seasonal variations in water-balance quantities observed in the field. LEACHM and HYDRUS predicted total R during the monitoring period with reasonable accuracy (within 18mm using general mean parameters), but the timing of predicted and observed R events was different. In contrast, UNSAT-H consistently overpredicted R by at least 239mm . Evapotranspiration was predicted reliably (within 60mm ) with all three codes when data from the first year were excluded. However, all three codes overpredicted ET in late winter and early spring, when snowmelt was occurring and S was accumulating in the field. Consequently, S generally was underpredicted by all three codes. Predicted and measured percolation were in good agreement (within 1mm∕year ), except during the first year. Results of the comparison indicate that cover modelers should scrutinize runoff predictions for reasonableness and carefully account for snow accumulation, snow melt, and ET during snow cover. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A4%2847 [...]

Field data and water-balance predictions for a monolithic cover in a semiarid climate / G. L. Bohnhoff in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°3 (Mars 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 333–348 Titre : Field data and water-balance predictions for a monolithic cover in a semiarid climate Type de document : texte imprimé Auteurs : G. L. Bohnhoff, Auteur ; A. S. Ogorzalek, Auteur ; C. H. Benson, Auteur Année de publication : 2009 Article en page(s) : pp. 333–348 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Evapotranspiration  Landfill  Numerical  model  Unsaturated  flow  Waste  management  Water  balance  Unsaturated  soils  Arid  lands  Field  tests Résumé : Water-balance predictions made using four codes (UNSAT-H, VADOSE/W, HYDRUS, and LEACHM) are compared with water-balance data from a test section located in a semiarid climate simulating a monolithic water-balance cover. The accuracy of the runoff prediction (underprediction or overprediction) was found to affect the accuracy of all other water-balance quantities. Runoff was predicted more accurately when precipitation was applied uniformly throughout the day, the surface layer was assigned higher saturated hydraulic conductivity, or when Brooks-Corey functions were used to describe the hydraulic properties of the cover soils. However, no definitive or universal recommendation could be identified that would provide reasonable assurance that runoff mechanisms are properly simulated and runoff predictions are accurate. Evapotranspiration and soil-water storage were predicted reasonably well (within ≈25mm∕yr ) when runoff was predicted accurately, general mean hydraulic properties were used as input, and the vegetation followed a consistent seasonal transpiration cycle. However, percolation was consistently underpredicted ( >3mm total) even when evapotranspiration and soil-water storage were predicted reliably. Better agreement between measured and predicted percolation (or a more conservative prediction) was obtained using mean properties for the soil-water characteristic curve and increasing the saturated hydraulic conductivity of the cover soils by a factor between 5 and 10. Evapotranspiration and soil-water storage were predicted poorly at the end of the monitoring period by all of the codes due to a change in the evapotranspiration pattern that was not captured by the models. The inability to capture such changes is a weakness in current modeling approaches that needs further study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2833 [...] [article] Field data and water-balance predictions for a monolithic cover in a semiarid climate [texte imprimé] / G. L. Bohnhoff, Auteur ; A. S. Ogorzalek, Auteur ; C. H. Benson, Auteur . - 2009 . - pp. 333–348. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 333–348 Mots-clés : Evapotranspiration  Landfill  Numerical  model  Unsaturated  flow  Waste  management  Water  balance  Unsaturated  soils  Arid  lands  Field  tests Résumé : Water-balance predictions made using four codes (UNSAT-H, VADOSE/W, HYDRUS, and LEACHM) are compared with water-balance data from a test section located in a semiarid climate simulating a monolithic water-balance cover. The accuracy of the runoff prediction (underprediction or overprediction) was found to affect the accuracy of all other water-balance quantities. Runoff was predicted more accurately when precipitation was applied uniformly throughout the day, the surface layer was assigned higher saturated hydraulic conductivity, or when Brooks-Corey functions were used to describe the hydraulic properties of the cover soils. However, no definitive or universal recommendation could be identified that would provide reasonable assurance that runoff mechanisms are properly simulated and runoff predictions are accurate. Evapotranspiration and soil-water storage were predicted reasonably well (within ≈25mm∕yr ) when runoff was predicted accurately, general mean hydraulic properties were used as input, and the vegetation followed a consistent seasonal transpiration cycle. However, percolation was consistently underpredicted ( >3mm total) even when evapotranspiration and soil-water storage were predicted reliably. Better agreement between measured and predicted percolation (or a more conservative prediction) was obtained using mean properties for the soil-water characteristic curve and increasing the saturated hydraulic conductivity of the cover soils by a factor between 5 and 10. Evapotranspiration and soil-water storage were predicted poorly at the end of the monitoring period by all of the codes due to a change in the evapotranspiration pattern that was not captured by the models. The inability to capture such changes is a weakness in current modeling approaches that needs further study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2833 [...]