Directeur de Recherche
Voici les éléments 1 - 10 sur 184
- PublicationAccès libre
- PublicationAccès librePrediction-Focused Subsurface Modeling: Investigating the Need for Accuracy in Flow-Based Inverse Modeling(2014-1-10)
;Scheidt, Céline ;Caers, Jef
- PublicationAccès libreModeling Fine-Scale Geological Heterogeneity?Examples of Sand Lenses in Tills(2013-1-10)
;Kessler, Timo Christian ;Comunian, Alessandro ; ; ;Nilsson, Bertel ;Klint, Knud ErikBjerg, Poul Løgstrup
- PublicationAccès libreConditioning facies simulations with connectivity data(2008-1-10)
- PublicationAccès libreA workflow to facilitate three-dimensional geometrical modelling of complex poly-deformed geological units(2009-1-10)
;Maxelon, Michael ; ;Courrioux, Gabriel ;Brändli, MartinMancktelow, Neil
- PublicationMétadonnées seulement
- PublicationMétadonnées seulementWater conflicts in the Kouris catchment (Cyprus) : data analysis and numerical modelling(2002)
;Boronina, Anastasia ; ;Balderer, WernerChristodoulides, Andreas
- PublicationAccès libreForecasting the number of soil samples required to reduce remediation cost uncertainty(2004-1-10)
;Demougeot-Renard, Helene ;De Fouquet, ChantalSampling scheme design is an important step in the management of polluted sites. It largely controls the accuracy of remediation cost estimates. In practice, however, sampling is seldom designed to comply with a given level of remediation cost uncertainty. In this paper, we present a new technique that allows one to estimate of the number of samples that should be taken at a given stage of investigation to reach a forecasted level of accuracy. The uncertainty is expressed both in terms of volume of polluted soil and overall cost of remediation. This technique provides a flexible tool for decision makers to define the amount of investigation worth conducting from an environmental and financial perspective. The technique is based on nonlinear geostatistics (conditional simulations) to estimate the volume of soil that requires remediation and excavation and on a function allowing estimation of the total cost of remediation (including investigations). The geostatistical estimation accounts for support effect, information effect, and sampling errors. The cost calculation includes mainly investigation, excavation, remediation, and transportation. The application of the technique on a former smelting work site (lead pollution) demonstrates how the tool can be used. In this example, the forecasted volumetric uncertainty decreases rapidly for a relatively small number of samples (20-50) and then reaches a plateau (after 100 samples). The uncertainty related to the total remediation cost decreases while the expected total cost increases. Based on these forecasts, we show how a risk-prone decision maker would probably decide to take 50 additional samples while a risk-averse decision maker would take 100 samples.
- PublicationAccès libreStudy of stable isotopes in the Kouris catchment (Cyprus) for the description of the regional groundwater flow(2005-1-10)
;Boronina, Anastasia ;Balderer, Werner ;Stichler, WillibaldThe stable isotopes of oxygen and hydrogen in groundwater and precipitation were integrated for the description of groundwater flow in the Kouris catchment (Cyprus). The catchment consists of an ophiolitic complex in the North and sediments in the South. It is characterized by strong heterogeneity of the underground media and steep slopes of the topography. The regression line, constructed from the data of 70 rainfall samples, is described by the equation: delta D = 6.6 delta(18)O + 10.9, which shows evaporation during precipitation. The altitude gradients in the precipitation were estimated to be -1.7 parts per thousand/100 m for delta D and -0.27/100 m for delta(18)O. The stable isotope analysis of 234 groundwater samples reflected fractionation due to evaporation. The origin of groundwaters in the catchment was described based on the regression equation between surface elevations and delta D contents for 33 selected springs of the ophiolitic complex. It was found that the groundwaters in the ophiolitic aquifer and in the consolidated sediments originated from local recharge at high and low altitudes, respectively. On the contrary, the groundwater in the alluvium aquifer originates from the high altitudes in the ophiolitic complex. Additionally, delta D data were used for the calibration of the recharge rates for a steady state groundwater flow and transport model. The resulting calibrated total steady state recharge rate was 100-130 mm per year. (c) 2004 Elsevier B.V. All rights reserved.
- PublicationAccès libreApplication of tritium in precipitation and in groundwater of the Kouris catchment (Cyprus) for description of the regional groundwater flow(Elsevier, 2005)
;Boronina, Anastasia ; ;Werner BaldererStichler, WillibaldThe Kouris catchment is located in the south of the Troodos massif in Cyprus. It constitutes one of the biggest catchments of the island with important freshwater resources. Geologically, the catchment includes an ophiolitic complex outcropping in the north which is overlaid by sedimentary rocks in the south. The hydrology is driven by a Mediterranean climate, a mountainous topography, and a complex distribution of the hydrogeological properties resulting from the complex geology.
To improve the understanding of groundwater hydrology of the Kouris catchment, 176 groundwater and precipitation samples were collected and their 3H contents were analyzed. The three-dimensional 3H transport in the groundwater was simulated by the PMPATH code. For numerical modelling, a regional input function of 3H in precipitation was constructed from a linear regression between data for Cyprus and for neighboring meteorological stations. The calculated residence times for the groundwaters in the sedimentary aquifer and Pillow Lavas were greater than 48 a and were considerably greater than those of the ophiolitic complex (14–30 a). The calibrated aquifer porosities were in a range of 0.05–0.06. The PMPATH model was applied for delineation of spring catchments that were represented by quite narrow zones of lengths up to 5 km.
Another contribution resulting from the 3H analysis was a better understanding of the river–aquifer interactions. In most of the southern part, the lithified sediments received only negligible amounts of water from the rivers, while the alluvial aquifer contained mostly water infiltrated from rivers. The largest springs in the southern part, associated with the alluvial aquifer, also discharged water identical to that in the rivers.