User's documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model

Harbaugh, Arlen W.; McDonald, Michael G.

doi:10.3133/ofr96485

Cited by 532 publications

(407 citation statements)

References 5 publications

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“…It was based on the MODFLOW code (Harbaugh and McDonald, 1996) and had objectives and limitations discussed by Boronina et al (2003). In spite of a good fit of observed and simulated piezometric heads, the calibration of the model based only on piezometric observations resulted in a reliable relation 'recharge rates-transmissivities' rather than in absolute values of the parameters.…”

Section: Calibration Of the Steady State Groundwater Model With The Smentioning

confidence: 99%

Study of stable isotopes in the Kouris catchment (Cyprus) for the description of the regional groundwater flow

Boronina

Balderer

Renard

et al. 2005

Journal of Hydrology

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The 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: dDZ6.6d 18 OC10.9, which shows evaporation during precipitation. The altitude gradients in the precipitation were estimated to be K1.7‰/100 m for dD and -0.27/100 m for d 18O. 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 dD 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, dD 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.

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Section: Calibration Of the Steady State Groundwater Model With The Smentioning

confidence: 99%

Study of stable isotopes in the Kouris catchment (Cyprus) for the description of the regional groundwater flow

Boronina

Balderer

Renard

et al. 2005

Journal of Hydrology

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“…Die analyse der Grundwasserproben aus den iPV und aus den Direct-PushMessstellen wird bei Herold et al (2008) beschrieben. (Harbaugh & McDonald 1996) und MODPATH (Pollock 1994) Ergebnisse tabelle 1 stellt die ermittelten Schadstofffrachten an dem untersuchten teilstück der Kontrollebene (cP2-3) für die im testfeld Süd dominierenden Schadstoffkomponenten dar, die (i) mittels Interpolation von Punktkonzentrationsmessungen entsprechend Gleichung 3 und (ii) mithilfe des Programms cStreaM und des numerischen Standortmodells für das Gelände berechnet wurden. Die für die interpolation von Punktkonzentrationsmessungen verwendeten Daten sind in Tabelle 2 dargestellt, wobei die hydraulischen Durchlässigkeitsbeiwerte an den rammpegeln durch interpolation der pumpversuchsbasierten Werte an den iPVbrunnen bestimmt wurden.…”

Section: Introductionunclassified

Bestimmung der Schadstofffrachten an Kontrollebenen mithilfe von Punktkonzentrationsmessungen und Immissionspumpversuchen – ein Vergleich

Herold¹,

Ptak²,

Grathwohl

2008

Grundwasser

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Kurzfassung Die Quantifizierung der Schadstofffrachten an Kontrollebenen ist eine entscheidende Voraussetzung zur Bewertung von Grundwasserschadensfällen und zum Nachweis von Natural Attenuation. Hierzu können zwei verschiedene Erkundungsansätze, die Frachtbestimmung basierend auf der Interpolation von Punktkonzentrationsmessungen sowie Immissionspumpversuche, verwendet werden. Punktkonzentrationsmessungen haben den entscheidenden Nachteil, dass in der Regel nur eine ausreichend große Anzahl sicher stellen kann, dass die gesamte Abstromfahne erfasst wird. immissionspumpversuche können wiederum relativ hohe Grundwasseraufbereitungs-und entsorgungskosten verursachen und nur in ausreichend durchlässigen Grundwasserleitern durchgeführt werden. ein Vergleich der Ergebnisse aus der Anwendung beider Erkundungsansätze kann eine Hilfestellung bei der Konzipierung von Erkundungsmaßnahmen bieten. Daher wurden die Resultate von vier Immissionspumpversuchen mit Messungen in 13, in kurzem Abstand zueinander errichteten, Direct-Push-Messstellen auf dem Gelände eines ehemaligen Gaswerks verglichen. Es konnte festgestellt werden, dass die Vergleichbarkeit der erkundungsergebnisse je nach Standortsituation stark von der Heterogenität der Verteilung der Schadstoffe im Grundwasserleiter abhängt. Die Studie legt nahe, dass insbesondere bei stark heterogenen Verhältnissen im Grundwasserleiter immissionspumpversuche bei der Wahl der Erkundungsmethode bevorzugt werden sollten, da die Interpolation von Punktkonzentrationsmessungen selbst im Falle eines relativ engmaschigen Messstellennetzes zu einer großen Erkundungsunsicherheit führen kann. A comparison of mass flow rate estimates based on point scale and integral measurementsAbstract The quantification of contaminant mass flow rates at control planes is an essential prerequisite for assessing contaminated sites and for providing evidence of natural attenuation. two different investigation approaches are usually implemented: mass flow estimation based on interpolation of point scale concentration measurements, and integral pumping tests. Point scale concentration measurements have the crucial disadvantage that in general, only a sufficiently dense monitoring network can ensure that the plume is completely covered. On the other hand, integral pumping tests may require expensive groundwater treatment and disposal and are only applicable in sufficiently conductive aquifers. a comparison of results from the application of both approaches can help with respect to the selection of a subsurface investigation method. a former gasworks site was chosen to compare the results of four integral pumping tests and measurements obtained from 13 direct-pushwells, which were installed at a relatively close spacing. The comparison shows that the correlation of the two methods depends strongly on the heterogeneity of the contaminant distribution within the aquifer. the study suggests that especially in the case of heterogeneous settings, integral pumping tests should be chosen for subsurface investigation...

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“…Details regarding the aquifer heterogeneity are available in Michalak and Kitanidis [2004b]. The flow solution is obtained using MODFLOW [McDonald and Harbaugh, 1988;Harbaugh and McDonald, 1996].…”

Section: Example 3: Estimation Of Historical Contaminant Distributionmentioning

confidence: 99%

A Gibbs sampler for inequality‐constrained geostatistical interpolation and inverse modeling

Michalak

2008

Water Resources Research

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[1] Interpolation and inverse modeling problems are ubiquitous in environmental sciences. In many applications, the parameters being estimated or mapped have physical constraints, such as nonnegativity (e.g. concentration, hydraulic conductivity), solubility limits, censored data (e.g. due to dry wells or detection limits), and other physical boundaries or missing data. Geostatistical interpolation and inverse modeling techniques have often been applied for estimating such parameters, but these methods typically cannot enforce physical constraints. This paper describes a statistically rigorous and computationally efficient Gibbs sampler, a Markov chain Monte Carlo technique, based on an a priori truncated Gaussian distribution model, which allows for multiple and variable physical constraints to be enforced within a geostatistical framework. Sample interpolation and inverse modeling applications confirm that estimates, uncertainty bounds and conditional simulations reflect the specified constraints, leading to conclusions that are more consistent with the underlying conceptual model, and provide a more accurate measure of the posterior uncertainty of the parameters being estimated. In addition, especially in inverse modeling applications, a posteriori confidence bounds are narrower even in areas where constraints are not imposed. The method is applicable in multiple dimensions, for data with or without measurement error, and with any variogram model.

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User's documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model

Cited by 532 publications

References 5 publications

Study of stable isotopes in the Kouris catchment (Cyprus) for the description of the regional groundwater flow

Study of stable isotopes in the Kouris catchment (Cyprus) for the description of the regional groundwater flow

Bestimmung der Schadstofffrachten an Kontrollebenen mithilfe von Punktkonzentrationsmessungen und Immissionspumpversuchen – ein Vergleich

A Gibbs sampler for inequality‐constrained geostatistical interpolation and inverse modeling

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