The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Kees Maas - One of the best experts on this subject based on the ideXlab platform.
-
identification and explanation of a change in the Groundwater Regime using time series analysis
Ground Water, 2019Co-Authors: Christophe Obergfell, Mark Bakker, Kees MaasAbstract:: Time series analysis is applied to identify and analyze a transition in the Groundwater Regime in the aquifer below the sand ridge of Salland in the Netherlands, where Groundwater Regime refers to the range of head variations throughout the seasons. Standard time series analysis revealed a discrepancy between modeled and observed heads in several piezometers indicating a possible change in the Groundwater Regime. A new time series modeling approach is developed to simulate the transition from the initial Regime to the altered Regime. The transition is modeled as a weighted sum of two responses, one representing the initial state of the system, the other representing the altered state. The inferred timing and magnitude of the change provided strong evidence that the transition was the result of significant dredging works that increased the river bed conductance of the main river draining the aquifer. The plausibility of this explanation is corroborated by an analytical model. This case study and the developed approach to identify a change in the Groundwater Regime are meant to stimulate a more systematic application of time series analysis to detect and understand changes in Groundwater systems which may easily go unnoticed in Groundwater flow modeling.
Christophe Obergfell - One of the best experts on this subject based on the ideXlab platform.
-
identification and explanation of a change in the Groundwater Regime using time series analysis
Ground Water, 2019Co-Authors: Christophe Obergfell, Mark Bakker, Kees MaasAbstract:: Time series analysis is applied to identify and analyze a transition in the Groundwater Regime in the aquifer below the sand ridge of Salland in the Netherlands, where Groundwater Regime refers to the range of head variations throughout the seasons. Standard time series analysis revealed a discrepancy between modeled and observed heads in several piezometers indicating a possible change in the Groundwater Regime. A new time series modeling approach is developed to simulate the transition from the initial Regime to the altered Regime. The transition is modeled as a weighted sum of two responses, one representing the initial state of the system, the other representing the altered state. The inferred timing and magnitude of the change provided strong evidence that the transition was the result of significant dredging works that increased the river bed conductance of the main river draining the aquifer. The plausibility of this explanation is corroborated by an analytical model. This case study and the developed approach to identify a change in the Groundwater Regime are meant to stimulate a more systematic application of time series analysis to detect and understand changes in Groundwater systems which may easily go unnoticed in Groundwater flow modeling.
Gianfranco Urciuoli - One of the best experts on this subject based on the ideXlab platform.
-
seasonal Groundwater Regime in an unsaturated pyroclastic slope
Geotechnique, 2013Co-Authors: Raffaele Papa, Marianna Pirone, Marco Valerio Nicotera, Gianfranco UrciuoliAbstract:Rainwater infiltration is the mechanism that leads or predisposes unsaturated pyroclastic slopes to failure by reducing matric suction and hence reducing the shear strength. Therefore, Groundwater flow analysis is an important tool to investigate slope stability as well as predict conditions caused by heavy rainfall. Analysis and prediction quality can be greatly improved by in situ monitoring. In this framework, this paper describes the results of an ongoing experimental research project on mudflows, based on monitoring of a test site in a typical geological environment in western Campania. The site was selected to carry out extensive laboratory and in situ experimentation, consisting of field monitoring of climatic conditions, matric suction and water content. The suction data span about 4 years, while water content data cover about 2 years. Considered together, these data allow clear identification of seasonal fluctuations of the hydraulic properties in the subsoil, while giving interesting information...
-
seasonal effects in the Groundwater Regime of unsaturated slopes
2012Co-Authors: Marianna Pirone, Gianfranco UrciuoliAbstract:Landslides in partially saturated pyroclastic slopes are strongly linked to rainwater infiltration, which is the main factor responsible for pore pressure and shear strength variations in shallow subsoil. Monitoring of the Groundwater Regime allows the most critical period for slope stability to be identified and the relationship between critical pore pressure and rainfall to be explored. This paper describes the monitoring of an unsaturated pyroclastic slope instrumented at Monteforte Irpino in southern Italy (Pirone et al., 2010), where suction and volumetric water content measured at different depths were collected from 2006 to 2011. Using this database, typical aspects of the Groundwater Regime are described. The maximum water content is observed to be significantly lower than the saturated value measured in the laboratory (Nicotera et al., 2010). This condition affects permeability attained in situ during the wet period of the year and hence infiltration.
-
Groundwater Regime in a slope stabilized by drain trenches
Mathematical and Computer Modelling, 2006Co-Authors: B Dacunto, Gianfranco UrciuoliAbstract:Drains are widely used in civil engineering as control works against slope instability in saturated clayey soils. The action of drains reduces pore pressures in the subsoil and consequently increases effective stresses and soil shear strength. Although drains are widely used in geotechnical design, their effect on slope stability is not fully understood and modeled. It is well known that the water table is subjected to broad variations due to atmospheric conditions and that the critical situation for slopes occurs during the wet season, when pore pressure in the subsoil attains its maximum. The real role of drains consists of avoiding this peak of pore pressure that could cause land sliding. Despite the behavior described, analyses proposed in the literature solve cases of drains working in slopes under steady hydraulic conditions at the boundaries. In this work we present a transient analysis of the phenomenon by considering the work of drain trenches in a transient Regime due to variations in hydraulic conditions at the ground surface, as a consequence of rainfall. Under this hypothesis, the effect of drains is calculated to be greater than would be predicted by available design methods.
-
effect of Groundwater Regime on the behaviour of clayey slopes
Canadian Geotechnical Journal, 2004Co-Authors: Luciano Picarelli, Gianfranco Urciuoli, Claudia RussoAbstract:It is well known that many landslides, which occur every year in the world, are triggered by rainfall. The mechanics of slope movements due to pore pressure changes are not completely understood, however, and thus are the focus of this paper. Both the case of first-time slides and that of landslide reactivation are examined. It is shown that simple models can reproduce the processes of slope failure and may help in predicting slope behaviour.Key words: slope, failure, landslide, analysis, water table, clay.
F H A Van Weert - One of the best experts on this subject based on the ideXlab platform.
-
the impact of glaciation on the Groundwater Regime of northwest europe
Global and Planetary Change, 1996Co-Authors: G S Boulton, P E Caban, K Van Gijssel, A Leijnse, M Punkari, F H A Van WeertAbstract:Abstract Growth of mid-latitude ice sheets during the glacial cycles of the Quaternary repeatedly reorganises the pattern of Groundwater flow on a continent-wide scale. Relatively small scale non-glacial catchments are replaced by catchments which are integrated on the scale of continental ice sheets. Simulations are presented of the response to glaciation of a large part of the western European Groundwater system during the last two (Saalian, Weichselian) glacial cycles. A two-dimensional model along an ice sheet flowline from western Sweden to The Netherlands illustrates the impact of glaciation on flow in the vertical plane, and a vertically integrated model illustrates its impact on areal patterns of flow. Hydraulics heads, hydraulic gradients and flow velocities are increased far above their modern values, and relatively shallow aquifers are completely flushed out during glacial periods. There are significant implications for Groundwater chemistry and geological structures. Large seepage pressures generated near to ice sheet margins and major impacts on the distribution of effective pressures will produce structures such as hydrofractures, sediment dykes, sediment volcanoes, loading structures etc. The model can be readily applied to hydrocarbon resorvoirs.
Olaf Kolditz - One of the best experts on this subject based on the ideXlab platform.
-
numerical analysis of the Groundwater Regime in the western dead sea escarpment israel west bank
Environmental Earth Sciences, 2013Co-Authors: Agnes Grabe, Tino Rodiger, Karsten Rink, Thomas Fischer, Wenqing Wang, Christian Siebert, Olaf KolditzAbstract:Water is scarce in the semi-arid to arid regions around the Dead Sea, where water supply mostly relies on restricted Groundwater resources. Due to increasing population in this region, the regional aquifer system is exposed to additional stress. This results in the continuous decrease in water level of the adjacent Dead Sea. The interaction of an increasing demand for water due to population growth and the decrease of Groundwater resources will intensify in the near future. Thus, the water supply situation could worsen significantly unless sustainable water resource management is conducted. In this study, we develop a regional Groundwater flow model of the eastern and southern Judea Group Aquifer to investigate the Groundwater Regime in the western Dead Sea drainage basin of Israel and the West Bank. An extensive geological database was developed and consequently a high-resolution structural model was derived. This structural model was the basis for various Groundwater flow scenarios. The objective was to capture the spatial heterogeneity of the aquifer system and to apply these results to the southern part of the study area, which has not been studied in detail until now. As a result we analyzed quantitatively the flow Regime, the Groundwater mass balance and the hydraulic characteristics (hydraulic conductivity and hydraulic head) of the cretaceous aquifer system and calibrated them with PEST. The calibrated Groundwater flow model can be used for integrated Groundwater water management purposes in the Dead Sea area, especially within the framework of the SUMAR-Project.
-
Numerical analysis of the Groundwater Regime in the western Dead Sea escarpment, Israel + West Bank
Environmental Earth Sciences, 2012Co-Authors: Agnes Grabe, Tino Rodiger, Karsten Rink, Thomas Fischer, Wenqing Wang, Christian Siebert, Olaf KolditzAbstract:Water is scarce in the semi-arid to arid regions around the Dead Sea, where water supply mostly relies on restricted Groundwater resources. Due to increasing population in this region, the regional aquifer system is exposed to additional stress. This results in the continuous decrease in water level of the adjacent Dead Sea. The interaction of an increasing demand for water due to population growth and the decrease of Groundwater resources will intensify in the near future. Thus, the water supply situation could worsen significantly unless sustainable water resource management is conducted. In this study, we develop a regional Groundwater flow model of the eastern and southern Judea Group Aquifer to investigate the Groundwater Regime in the western Dead Sea drainage basin of Israel and the West Bank. An extensive geological database was developed and consequently a high-resolution structural model was derived. This structural model was the basis for various Groundwater flow scenarios. The objective was to capture the spatial heterogeneity of the aquifer system and to apply these results to the southern part of the study area, which has not been studied in detail until now. As a result we analyzed quantitatively the flow Regime, the Groundwater mass balance and the hydraulic characteristics (hydraulic conductivity and hydraulic head) of the cretaceous aquifer system and calibrated them with PEST. The calibrated Groundwater flow model can be used for integrated Groundwater water management purposes in the Dead Sea area, especially within the framework of the SUMAR-Project.
