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Models – Repositories of Knowledge

Edited by Sascha E. Oswald, Olaf Kolditz & Sabine Attinger IAHS Publ. 355 (2012) ISBN 978-1-907161-34-6, 374 + x pp. Price £77.00

Questions of global and climate change, use of energy resources and waste deposition, mean that work with groundwater now needs to include the interfaces to the atmosphere, surface waters and deeper formations that are potentially used for geothermal energy and CO2 storage, and ModelCARE2011 reflected that. More than ever, models are means to integrate information from different and manifold sources, allowing a better conceptual view of systems as a whole and improving understanding of them, i.e. models are repositories of knowledge. This volume considers: Parameter estimation, Uncertainty, Numerical and computational methods, Reactive transport and bioremediation, Stochastic and multi-scale models, Couple processes in the subsurface, and Groundwater flow and climate.

Preface

The papers in this publication were presented at the ModelCARE 2011 conference held in Leipzig, Germany. The ModelCARE series, always centred around the calibration of groundwater models, how to deal with inherent uncertainties and how to judge reliability, has been a regular international conference series. It has offered the opportunity to meet experts deeply involved with analytical and numerical modelling of groundwater flow and transport processes. Measured data and experimental methods are mainly seen in the context of input and output of models, with a crucial link to reality and carrying the challenge the models have to cope with. Though not named groundwater, this has always been the central topic of the ModelCARE conferences. However, times and key people involved are regretfully changing, but there is also a chance for new developments. The role of groundwater is now combined with other environmental compartments and related processes. This is to a larger extent driven by questions of global and climate change, but is also related to energy resources, as well as the required waste deposition. Therefore, this ModelCARE has stressed the boundaries of groundwater, which are the interfaces to the atmosphere, surface waters and deeper formations that are potentially used for geothermal energy and CO2 storage. We believe this extended scope is the way forward to maintain ModelCARE as a model-centric conference of subsurface hydrology and its related disciplines.

This development is clearly reflected in the broader range of topics in an environmental hydrological context represented in this book. Still, models play an important role in the protection of groundwater as a freshwater resource. The subsurface heterogeneity is a key challenge still, but has to be handled not only in respect to groundwater flow and conservative transport, but also in respect to salinization, biogeochemical processes and exchange with surface waters and the atmosphere. Coupled processes in the subsurface still lack rigorous understanding, e.g. unsaturated flow, density-effects, multiphase flow including CO2 sequestration, exchange of solutes with solid phases and biomass, or transfer between streams and groundwater. At the same time, new developments in remote sensing and geophysical exploration provide more and different input to constrain, calibrate and validate models needing further development of existing standard approaches. More than ever, models are the mechanism to integrate information from different and manifold sources, allowing a better conceptual view of the system as a whole and the knowledge that may be retrieved on studying this system. That is, models are, in the best case, repositories of knowledge. This was the special title of the ModelCARE 2011. However, in the worst case scenario, models can end up as the opposite, as heaps of inconsistent data carry wrong conclusions. That is why we continuously have to take special care of conceptual models, numerical developments and integration of experimental data into models, to achieve the deeper, quantitative insight only models can provide. As a result, the community will profit from continuing the ModelCARE series.

The editors would like to thank the participants of the conference, especially the authors of papers and the participants who reviewed all the submitted papers. We appreciated the

participation and support of Eigenbrodt GmbH, Springer, Aranz Geo Ltd (Leapfrog) and Beta Analytic Inc as exhibitors and sponsors of the conference, and direct/indirect contributors to this red book volume. We also thank the conference organizing team at the UFZ and Penny Perrins and Cate Gardner at IAHS Press, Wallingford, for producing this volume.

Editors

Sascha E. OswaldUniversity of Potsdam

Institute of Earth and Environmental Sciences,Karl-Liebknechtstr. 24-25

14476 PotsdamGermany

Olaf KolditzDepartment of Environmental Informatics / Applied Environmental System Analysis

Helmholtz Centre for Environmental Research UFZ / TU DresdenLeipzig 03418, Germany

Sabine AttingerHelmholtz Centre for Environmental Research UFZ Department Computational Hydrosystems,

Permoserstrae 15,04318 Leipzig

Germany

Contents

Preface by Sascha E. Oswald, Olaf Kolditz & Sabine Attinger v

1 Parameter estimation

Simultaneous estimation of groundwater recharge rates, associated zone structures, and hydraulic conductivity values using fuzzy c-means clustering and harmony search optimisation algorithm: a case study of the Tahtali watershed M. Tamer Ayvaz & Alper Elçi

3

Numerical simulation of bench-scale tank experiments to quantify transverse dispersion E. Ballarini, S. Bauer, C. Eberhardt & C. Beyer

12

A two-stage strategy for efficient and effective calibration of distributed hydrological models C. Fischer, S. Kralisch, P. Krause & W.-A. Flügel

18

Investigation of the behaviour of two karst spring discharge reservoir models with respect to the initialization bias N. Mazzilli & V. Guinot & H. Jourde

27

Optimization of pilot points location for geostatistical inversion of groundwater flow Marco Panzeri, Alberto Guadagnini & Monica Riva

34

The usefulness of CPTs for deterministic, spatially heterogeneous, large-scale aquitard parameterisation B. Rogiers, D. Mallants, O. Batelaan, M. Gedeon, M. Huysmans & A. Dassargues

41

Quantitative evaluation of macroscopic longitudinal dispersivity for one-dimensional flow M. Saito, Y. Nishimura, D. Hoshino & K. Nakagawa

48

Calibrating a large-scale groundwater model using spaceborne remote sensing products: a test-case for the Rhine-Meuse basin Edwin H. Sutanudjaja, Ludovicus P.H. Van Beek, Steven M. De Jong, Frans C. Van Geer & Marc F. P. Bierkens

54

Numerical assessment of the direct-push permeameter for investigation of small-scale variations in hydraulic conductivity Ludwig Zschornack, Geoffrey C. Bohling, James J. Butler, Jr & Peter Dietrich

62

2 Uncertainty

A global uncertainty and sensitivity procedure for the assessment of groundwater recharge distribution via hydrological models G. Baroni, S. E. Oswald & C. A. Rivera Villarreyes

71

Reducing hydrograph uncertainty through subsurface characterization Steven B. Meyerhoff & Reed M. Maxwell

78

Consideration of parameters and boundary conditions uncertainties in water balance and solute transport simulation Amir Hassan Zadeh, Rene Blankenburg & Peter-Wolfgang Graeber

86

3 Numerical and computational methods

On the use of random conductivity fields to promote unstable flow of dense plumes Clemens Cremer & Thomas Graf

95

Improvement of performance and applicability of MODFLOW-2005: new NWT solver and χMD matrix solver package Motomu Ibaraki, Sorab Panday, Richard G. Niswonger & Christian D. Langevin

100

A GIS-linked unit response function approach to stochastic groundwater nonpoint source pollution modelling George Kourakos & Frank Klein & Thomas Harter

106

Visual preparation of hydrological models Karsten Rink, Thomas Fischer, Agnes Gräbe & Olaf Kolditz

113

A 3D interpolation algorithm for layered tilted geological formations using an adapted inverse distance weighting approach M. Walther, N. Böttcher & R. Liedl

119

Mixed 2D/3D visualization of a large scale groundwater study in a virtual reality centre B. Zehner, L. Bilke, T. Kalbacher, E. Kalbus, K. Rink, R. Rausch & O. Kolditz

127

Optimizing a long-term groundwater monitoring network using geostatistical methods Jay Krishna Thakur, Wolfgang Gossel, Holger Weiß & Peter Wycisk

133

4 Reactive transport and bioremediation

Using streamlines for highly-resolved, reactive transport for CO2 leakage contamination in groundwater Adam L. Atchley, Reed M. Maxwell, Alexis Navarre-Sitchler, Erica R. Siirila & John E McCray

141

Fate and transport modelling for monitored natural attenuation projects: what should be considered to maximise the value in decision making? P. H. Beck & B. Mann

149

Interpretation of hydrocarbon plume biodegradation in 2D bench-scale tank experiments by reactive transport modelling Christof Beyer, Elisabetta Ballarini, Robert D. Bauer, Christian Griebler & Sebastian Bauer

157

Compound-specific local and effective transverse dispersion coefficients for conservative and reactive mixing in heterogeneous porous media Gabriele Chiogna, Olaf A. Cirpka, Peter Grathwohl & Massimo Rolle

163

Reactive transport simulation of volatile organic compound removal in vertical flow soil filters Cecilia De Biase, Uli Maier, Sascha Oswald & Martin Thullner

169

The relation between pore-scale heterogeneity, bioavailability and bacterial mobility: a numerical modelling approach M. Gharasoo, F. Centler, I. Fetzer & M. Thullner

175

Modelling reactive transport of chlorinated hydrocarbons in groundwater under spatially varying redox conditions T. Greis, K. Helmholz, M. H. Schöniger & A. Haarstrick

181

Reactive transport modelling of weathering processes in intensely stratified mine tailings J. A. Meima, D. Rammlmair & M. Redwan

190

Importance of thermal dispersion in temperature plumes Nelson Molina-Giraldo, Philipp Blum & Peter Bayer

195

A flexible approach for coupled reactive transport modelling in post-mining areas 201

Mike Müller & Heike Büttcher

Evaluating effective reaction rates of kinetically driven solutes in large-scale, anisotropic media: human health risk implications Erica R. Siirila & Reed M. Maxwell

207

5 Stochastic and multi-scale models

Mixing processes in highly heterogeneous formations Francesca Boso & Alberto Bellin 217

A multidisciplinary study of sediments’ connectivity and transport parameters for aquifer analogues Mauro Giudici, Riccardo Bersezio, Fabrizio Felletti, Fulvia Baratelli, Laura Cattaneo, Emmanuele Cavalli, Diana dell’Arciprete, Mauro Mele, Lorenzo Pessina & Chiara Vassena

223

Analysis of time-drawdown data from heterogeneous leaky aquifer systems Cagri Gokdemir, Nadim K. Copty, Matthew Waterman & Angelos N. Findikakis

229

Generating land-use information to derive diffuse water and nitrate transfer at aquifer scale Gernot Klammler, Gerhard Rock, Hans Kupfersberger & Johann Fank

237

6 Coupled processes in the subsurface

Investigation of large-scale pressure propagation and monitoring for CO2 injection using a real site model Katharina Benisch & Sebastian Bauer

245

Comparison of equations of state for carbon dioxide for numerical simulations Norbert Böttcher, Joshua Taron, Olaf Kolditz, Rudolf Liedl & Chan-Hee Park

252

The coupled multiphase flow and reactive transport simulator OGS-Eclipse for CO2 storage simulations Bastian J. Graupner, Dedong Li, Katharina Benisch, Addisalem Bitew Mitiku, Christof Beyer & Sebastian Bauer

261

Harnessing the complex behaviour of ultra-dense and viscous treatment fluids as a strategy for aquifer remediation Utku Solpuker, Jared Hawkins, Robert Schincariol, Motomu Ibaraki & Franklin W. Schwartz

267

Simulation of flow in fractured rocks using effective stress-dependent parameters and aquifer consolidation Giona Preisig, Fabien J. Cornaton & Pierre Perrochet

273

Modes of free convective flow in fractured-porous rock Katharina Vujević & Thomas Graf

280

Determination of thermodynamics in a CO2 injection well using pressure and distributed temperature sensing B. Wiese, M. Nimtz, F. Möller, C. Otto, M. Kühn, A. Liebscher & C. Schmidt-Hattenberger

286

7 Groundwater flow and climate

Coastal aquifer management under drought conditions considering aquifer spatial variability V. Christelis, G. Kopsiaftis & A. Mantoglou

293

Impact of long-term changes in climate on groundwater resources in an arid setting Irina Engelhardt & Kerstin Prömmel

298

Simulation and prognosis of the impacts of climate changes on groundwater recharge under local conditions Issa Hasan, Jana Sallwey, Ulrike Haferkorn & Peter-Wolfgang Graeber

306

Climate and land-use change impacts on groundwater recharge Bertrand Leterme & Dirk Mallants

313

What are the key parameters for soil hydrological models in climate impact studies under different settings? J. Palm, H. Stöfen, W. H. M. Duijnisveld & W. Schneider

320

Wind energy forecast ensembles using a fully-coupled groundwater to atmosphere model John L. Williams, III & Reed M. Maxwell

327

Flow in the unsaturated zone to quantify Acid Mine Drainage: numerical and analytical approaches Martí Bayer-Raich & Salvador Jordana

333

Development of the hourly hydrological model for mountainous basins using the storage function method and the Diskin-Nazimov infiltration model Kazumasa Fujimura, Kiyohara Shiraha, Shinjiro Kanae & Masahiro Murakami

338

Development of a regional groundwater flow model along the western Dead Sea Escarpment Agnes Gräbe, Tino Rödiger, Karsten Rink, Thomas Fischer & Olaf Kolditz

345

Propagating subsurface uncertainty to the atmosphere using fully-coupled, stochastic simulations John L. Williams, III & Reed M. Maxwell

351

Multiobjective calibration of coupled soil–vegetation–atmosphere models Thomas Wöhling, Sebastian Gayler, Joachim Ingwersen, Thilo Streck, Jasper A. Vrugt & Eckart Priesack

357

Key word index 365

Author index 369

Models – Repositories of Knowledge(Proceedings ModelCARE2011 held at Leipzig, Germany, in September 2011) (IAHS Publ. 355, 2012), 3-11.

Simultaneous estimation of groundwater recharge rates, associated zone structures, and hydraulic conductivity values using fuzzy c-means clustering and harmony search optimisation algorithm: a case study of the Tahtali watershed

M. TAMER AYVAZ1 & ALPER ELÇI2

1 Department of Civil Engineering, Pamukkale University, 20070 Denizli, Turkey2 Department of Environmental Engineering, Dokuz Eylül University, 35160 Buca-Izmir, [email protected]

Abstract The aim of this study is to present a linked simulation–optimisation model to estimate the groundwater recharge rates, their associated zone structures, and hydraulic conductivity values for regional, steady-state groundwater flow models. For the zone structure estimation problem the fuzzy c-means clustering (FCM) method was used. The association of zone structures with the spatial distribution of groundwater recharge rates was then accomplished using an optimisation approach where the heuristic harmony search (HS) algorithm was used. Since the solution was obtained by a heuristic algorithm, the optimisation process was able to use a non-specific initial solution, i.e. an initial solution that does not have to be close to the final solution. The HS-based optimisation model determines the shape of zone structures, their corresponding recharge rates and hydraulic conductivity values by minimizing the root mean square error () between simulated and observed head values at observation wells and springs, respectively. To determine the best recharge zone structure, the identification procedure starts with computation of one zone and systematically increased the zone number until the optimum zone structure is identified. Subsequently, the performance of the proposed simulation–optimisation model was evaluated on the Tahtali watershed (Izmir, Turkey), an urban watershed for which a seasonal steady-state groundwater flow model was developed for a previous study. The results of our study demonstrated that the proposed simulation–optimisation model is an effective way to calibrate the groundwater flow models for the cases where tangible information about the groundwater recharge distribution does not exist.Key words groundwater recharge; zone structure estimation; optimisation; harmony search


Numerical simulation of bench-scale tank experiments to quantify transverse dispersion

E. BALLARINI1, S. BAUER1, C. EBERHARDT2 & C. BEYER1

1 Institute for Geosciences, University of Kiel, Ludewig-Meyn-Str. 10, D-24118 Kiel, Germany [email protected]

2 Center for Applied Geosciences, University of Tübingen, Sigwartstraße 10, D-72076 Tübingen, Germany

Abstract Transverse mixing has been studied within the context of contaminant transport in aquifers, as it represents an important mixing process and is an essential prerequisite for geochemical and biodegradation reactions. In this work, the effects of different hydraulic parameters on plume development in homogeneous and heterogeneous porous media were investigated. A series of detailed and well controlled 2D bench-scale tank experiments, where one or more conservative tracers are injected, was performed in a homogeneous porous medium consisting of a fine matrix (0.25–0.3 mm) and in a heterogeneous medium that has the same matrix grain size but includes a more permeable lens (grain size 1.0–1.5 mm). The experiments were evaluated by numerical simulation. Results of a sensitivity analysis show that contrary to the homogeneous experiments, the tracer distribution is not very sensitive to variations in transverse dispersivity. In fact, only the order of magnitude of this parameter can be estimated by fitting the numerical results to the laboratory measurements. The plume shape and position in the heterogeneous set-up is mainly controlled by the contrast in the hydraulic conductivities between the matrix and the more permeable inclusion. A unique parameter set could be calibrated to closely fit the measured concentration data. For porous media with a grain size of 0.2–0.3 mm and 1.0–1.5 mm (i.e. permeable inclusion in the heterogeneous set-up) and a porosity of 0.42 and 0.43, the fitted longitudinal

dispersivities are 3.49 × 10-4 m and 7.6 × 10-4 m, while the transverse dispersivities are 1.48 × 10-5 m and 7.1 × 10-5 m, respectively. Key words transverse mixing; heterogeneity; bench-scale experiments; conservative tracers


A two-stage strategy for efficient and effective calibration of distributed hydrological models

C. FISCHER, S. KRALISCH, P. KRAUSE & W.-A. FLÜGELDepartment of Geoinformatics, Hydrology and Modelling, School of Chemical and Earth Sciences,

Friedrich-Schiller-University, Jena, [email protected]

Abstract Calibration of distributed environmental models requires a high amount of either computing power or time, which can be a significant issue. As the computational effort for distributed models mainly depends on the number of spatial modelling entities, a promising approach for their optimization is to decrease these entities while sustaining the major characteristics of the model. In this article, a two-stage approach is presented to reduce the computational effort. In the first stage the number of spatial units is decreased, thus simplifying the original representation of the catchment. Spatial units are eliminated or merged with other units according to different merging rules (e.g. merging of similar units). The simplified model is used to carry out an initial calibration. In the second stage the process of simplification is reversed, i.e. the spatial representation of the catchment is restored stepwise. The obtained parameter sets are recalibrated. This is reiterated until the original distribution is recovered. To test and analyse this strategy, the distributed model J2000 is applied on the two meso-scale catchments of the Wilde Gera and Ilm, both located in central Germany. Furthermore, variations of the approach to simplify the spatial representation are analysed. Key words calibration; hydrology; spatial representation


Investigation of the behaviour of two karst spring discharge reservoir models with respect to the initialization bias

N. MAZZILLI1 & V. GUINOT2 & H. JOURDE2

1 EMMAH, UMR 1114 UAPV-INRA, Université d'Avignon et des Pays de Vaucluse, 33 rue Louis Pasteur, 84000 Avignon, France [email protected] HydroSciences Montpellier, UMR 5569 CNRS-IRD-UM1-UM2, Université Montpellier 2, Place Eugène Bataillon 34095, Montpellier, France

Abstract This paper investigates the analytical properties of the sensitivity to the initial conditions on the calibration and simulation results of two karst spring discharge reservoir models, based on the perturbation approach. The emphasis is laid on the influence of model nonlinearity on the sensitivity of the model output to the initial conditions. It is shown that depending on model structure, nonlinearity may either speed up or delay the dissipation of the initialisation bias. The analytical results are confirmed by application examples on real-world simulations.Key words initialisation bias; initial conditions; global model; perturbation approach; model sensitivity; calibration


mailto:[email protected]

Optimization of pilot points location for geostatistical inversion of groundwater flow

MARCO PANZERI, ALBERTO GUADAGNINI & MONICA RIVADIIAR, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, [email protected]

Abstract We investigate the influence of pilot points location on our ability to characterize key parameters describing a randomly heterogeneous porous medium via geostatistical inverse modelling. Our methodology is framed in a Maximum Likelihood (ML) context. We estimate the optimal location of pilot points through a differential evolution method (DEM) which we embed in the inversion of moment equations of groundwater flow. The DEM allows investigating a large number of candidate solutions to select those leading to the minimization of a given objective function through an algorithm that mimics the process of natural evolution. We explore the strength of the methodology by way of a synthetic example and we investigate the effect of the parameters embedded in the algorithm and the ability of model quality criteria such as negative log likelihood, the Bayesian criteria BIC and KIC and information criteria AIC, AICc and HIC to estimate the optimal pilot points locations.Key words stochastic inverse model; geostatistics; pilot points; model selection criteria; Differential Evolution Method


The usefulness of CPTs for deterministic, spatially heterogeneous, large-scale aquitard parameterisation

B. ROGIERS1,2, D. MALLANTS3, O. BATELAAN2,4, M. GEDEON1, M. HUYSMANS2 & A. DASSARGUES2,5

1 Institute for Environment, Health and Safety, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, BE-2400 Mol, Belgium [email protected] Dept. of Earth and Environmental Sciences, KU Leuven, Celestijnenlaan 200e – bus 2410, BE-3001 Heverlee, Belgium3 Groundwater Hydrology Program, CSIRO Land and Water, Waite Road – Gate 4, Glen Osmond SA 5064, Australia4 Dept. of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Pleinlaan 2, BE-1050 Brussels, Belgium

5 Dept. of Architecture, Geology, Environment and Civil Engineering (ArGEnCo), Université de Liège, B.52/3 Sart-Tilman, BE-4000 Liège, Belgium

Abstract Aquitards can be effectively parameterised and incorporated in a groundwater flow model by using standard cone penetration tests (CPTs). Several conceptually different realizations of an aquitard’s hydraulic conductivity field were evaluated based on: (i) conventional methods of soil behaviour type classification, (ii) recent relationships from the literature, and (iii) novel site-specific relations with hydraulic conductivity. We show that use of most of these CPT-based hydraulic conductivity estimations in groundwater flow modelling effectively enhance model performance based on absolute head values and gradients across the aquitard. Conceptual models that considered a spatially heterogeneous hydraulic conductivity for the aquitard performed better than the reference case with a uniform aquitard hydraulic conductivity. However, the hydraulic conductivity of thin heavy clay lenses, characteristic of the aquitard present in our study area, cannot be captured using these continuum approaches. The latter leads to a bias in the direct hydraulic conductivity predictions; an alternative is to invoke inverse modelling with the heterogeneous parameter fields. To address this issue, the concept of the boundary energy associated with the CPT signal is also introduced for characterising the presence of heavy clay lenses. Overall, the CPT-based concepts provide more accurate, robust, and high-resolution data-based parameterisation of the studied aquitard.Key words groundwater modelling; hydraulic conductivity; soil behaviour types; cone resistance; friction ratio; geostatistics; inverse optimisation; upscaling; cone penetration tests; model performance


Quantitative evaluation of macroscopic longitudinal dispersivity for one-dimensional flow

M. SAITO1, Y. NISHIMURA2, D. HOSHINO3 & K. NAKAGAWA4

1 Organization of Advanced Science and Technology, Kobe University, 1-1 Rokko-dai, Nada, Kobe 657-8501, [email protected] Graduate School of Engineering, Kobe University, 1-1 Rokko-dai, Nada, Kobe 657-8501, Japan3 Faculty of Engineering, Kobe University, 1-1 Rokko-dai, Nada, Kobe 657-8501, Japan4 Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyomachi, Nagasaki 852-8521, Japan

Abstract Macroscopic dispersivity is the most important factor for analysing the convection–dispersion equation (CDE) at the field scale, and it is well known that macroscopic dispersivities vary with the scale of observation. In this study, artificial heterogeneous hydraulic conductivity fields were generated with the stochastic fractal model (f model). Macroscopic dispersivities were evaluated for two-dimensional stochastic isotropic and anisotropic fields by performing dimensionless CDE simulations. The results showed that macroscopic dispersivity depends on the length of the contaminant source and the travel distances, as well as on field characteristics such as variability of hydraulic conductivity for one-dimensional flow. We proposed simple models for quantitatively evaluating the average values of macroscopic longitudinal dispersivity by performing two-dimensional numerical experiments. Further, we showed that macroscopic longitudinal dispersivities calculated by these models generally corresponded with that obtained from the field study.Key words macroscopic longitudinal dispersivity; stochastic fractal model; groundwater


Calibrating a large-scale groundwater model using spaceborne remote sensing products: a test-case for the Rhine-Meuse basin

EDWIN H. SUTANUDJAJA1, LUDOVICUS P. H. VAN BEEK1, STEVEN M. DE JONG1, FRANS C. VAN GEER1,3 & MARC F. P. BIERKENS1,2

1 Department of Physical Geography, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands [email protected] 2 Unit Soil and Groundwater Systems, Deltares, Utrecht, The Netherlands3 Netherlands Organization for Applied Scientific Research TNO, Utrecht, The Netherlands

Abstract The European Remote Sensing Soil Water Index (ERS SWI) fields, providing spatio-temporal soil moisture expressions, should be able to infer groundwater dynamics. In this study, we explore the possibility of using them to calibrate a coupled groundwater–land surface model. We apply a brute force calibration procedure by running several scenarios with varying parameter values of aquifer and upper soil properties. Results indicate that ERS SWI time series can be used in the calibration of such groundwater models by indirectly tuning groundwater recharge through changing the upper soil saturated hydraulic conductivities. It is shown that the scenarios showing good soil moisture dynamic performances also show good performances of their resulting groundwater head time series. However, the discharge performance is sensitive to the aquifer transmissivity. Discharge observations are thus also required for a more accurate model calibration.Key words ERS Soil Water Index; soil moisture; remote sensing; groundwater head; discharge


Numerical assessment of the direct-push permeameter for investigation of small-scale variations in hydraulic conductivity


LUDWIG ZSCHORNACK1, GEOFFREY C. BOHLING2, JAMES J. BUTLER, JR2 & PETER DIETRICH1

1 Helmholtz-Centre for Environmental Research -UFZ, Permoserstrasse. 15, 04318 Leipzig, Germany [email protected] Kansas Geological Survey, University of Kansas, 1930 Constant Avenue, Lawrence, Kansas 66047, USA

Abstract Characterization of hydraulic conductivity (K) variations on the scale of relevance for transport investigations is one of the main challenges faced in groundwater investigations. Recent work has shown that direct-push technology has great potential for providing high-resolution vertical profiles of subsurface parameters (e.g. K) in shallow unconsolidated formations. The direct-push permeameter (DPP) is a particularly promising tool for hydrostratigraphic characterization, but our understanding of its performance in highly heterogeneous formations is far from complete. This work is directed at advancing our understanding of DPP performance in highly heterogeneous media. We evaluate DPP potential through a series of numerical simulations using a heterogeneous configuration that is based on a previous aquifer analogue study. Our results demonstrate that the DPP can provide reliable K profiles, even in the presence of vertical K variations on the decimetre scale, and that the DPP configuration has a significant influence for the characterization of smaller-scale variations in K. Key words hydrostratigraphic characterization; model parameterization; direct push


A global uncertainty and sensitivity procedure for the assessment of groundwater recharge distribution via hydrological models

G. BARONI, S. E. OSWALD & C. A. RIVERA VILLARREYESInstitute for Earth and Environmental Science, University of Potsdam, Germany

[email protected]

Abstract Groundwater recharge is the key driver for groundwater flow and resulting transport at the catchment scale, but it is difficult to quantify. Hydrological models provide an option for evaluating an estimate of groundwater recharge. They can generally be used to estimate groundwater recharge rates over large spatial and temporal scales, and they can be applied for current or future scenario analysis as climate or land use changes. However, a serious limitation of current model applications is the non-availability of data and input parameters. In order to improve the reliability and the performance of hydrological models, in this study a general approach for the assessment of performance in the simulation of the groundwater recharge estimation is proposed. A so-called global uncertainty analysis is developed as a tool to evaluate the performance of the models. A global sensitivity analysis is defined and used as a complementary tool to find the most important sources of uncertainty. The procedure can take various sources of uncertainty into account, i.e. input data, parameters, either in scalar or spatially distributed form. This procedure is iterated in a loop for improving the performance of the models and to optimize the resource allocations. As a test example, the procedure is applied at an experimental site in northern Germany on a field scale, using the SWAP model, a 1D physical-based hydrological model. Further research will involve other spatially distributed hydrological models of different complexity and application on larger spatial scales.Key words groundwater recharge; Richards equation; global sensitivity analysis


Reducing hydrograph uncertainty through subsurface characterization

STEVEN B. MEYERHOFF & REED M. MAXWELL Colorado School of Mines, Hydrologic Science and Engineering Program, Integrated GroundWater Modelling Centre, 1516

Illinois Street, Golden, Colorado, USA [email protected]

Abstract Subsurface heterogeneity in saturated hydraulic conductivity is one of the largest sources of uncertainty in hydrology and hydrogeology. However, recent work has demonstrated that uncertainty in hydraulic conductivity can also impart significant uncertainty in runoff processes. Here, the role of site characterization in reducing hydrograph uncertainty and bias is demonstrated numerically. A fully integrated hydrologic model is used in a hypothetical experiment where a control hillslope is generated using correlated, Gaussian random fields. Direct measurements of hydraulic conductivity at varying density are obtained from this control simulation and assimilated into stochastic transient simulations. The hydrographs, resulting from integrated flow simulations for each realization, are shown to much more accurately match the control. Data assimilation resolves large-scale features in surface ponding and saturation. This implies that substantial reduction in hydrograph uncertainty may be reached through site characterization.Key words conditioning; groundwater surface water interactions; hillslope; runoff generation


Consideration of parameters and boundary conditions uncertainties in water balance and solute transport simulation

AMIR HASSAN ZADEH, RENE BLANKENBURG &

PETER-WOLFGANG GRAEBERTechnische Universitaet Dresden, Institute of Waste Management and Contaminated Site Treatment,

Pratzschwitzer Str. 15, 01796 Pirna, [email protected]

Abstract In this paper, a fuzzy-set theory-based approach is presented to incorporate the verbal expert knowledge with the uncertainties of the input data in a numerical model. It allows for the consideration of the fluctuation range of measurements, input parameters (e.g. soil and solute transport parameters) and boundary conditions. To extend numerical models to operate with fuzzy input parameters, interval arithmetic is used. Due to the characteristics of unsaturated zone processes, a nonlinear optimization problem occurs, where with given ranges of parameter sets min/max values must be found by means of gradient and objective function calculations. Furthermore, a second method, called fuzzy analysis library, is tested. This method provides a statistical approach based on an evolutionary algorithm so that no gradient calculations are performed. Both methods are applied to water flow and solute transport processes in the soil zone. The results of both methods are compared to each other.Key words water balance; solute transport; fuzzy set theory; uncertainty analysis; unsaturated zone; fuzzy analysis library


On the use of random conductivity fields to promote unstable flow of dense plumes

CLEMENS CREMER & THOMAS GRAFInstitute of Fluid Mechanics and Environmental Physics in Civil Engineering, Leibniz Universität Hannover, Appelstrasse 9A, 30167 Hannover, [email protected]

Abstract Flow under variable-density conditions is widespread, occurring in geothermal reservoirs, at waste disposal sites or due to saltwater intrusions. In nature, the migration of dense plumes typically results in the formation of vertical plume fingers which are known to be triggered by material heterogeneity. Random

hydraulic conductivity (K) fields are introduced into numerical simulations to incorporate pore-scale heterogeneity into homogenous media and to generate fingers realistically. That method is evaluated using a previously-conducted laboratory-scale sand tank experiment, which is numerically re-simulated here. Results indicate that the variance of ln(K) of 10 -3 (K in m s-1) realistically reproduces the number of plume fingers observed in the sand tank experiment. Introducing random K fields is therefore useful to accurately simulate dense plume fingering in saturated homogeneous porous media. A Monte Carlo approach showed that the simulation of dense plume fingers is realisation-independent.Key words model; groundwater; saturated; density; fingering; random K field; Monte Carlo


Improvement of performance and applicability of MODFLOW-2005: new NWT solver and χMD matrix solver package

MOTOMU IBARAKI1, SORAB PANDAY2, RICHARD G. NISWONGER3 & CHRISTIAN D. LANGEVIN4

1 Ohio State University, 125 South Oval Mall, Columbus, Ohio 43210, USA ibaraki.1 @ osu.edu 2 AMEC Environment & Infrastructure, 12801 Worldgate Drive, Suite 500, Herndon, Virginia 20170, USA 3 US Geological Survey, 2730 N. Deer Run Road, Carson City, Nevada 89701, USA 4 US Geological Survey, 411 National Center, Reston, Virginia 20192, USA

Abstract MODFLOW has been widely used for many years to investigate groundwater flow systems. In most numerical models, including MODFLOW, >80% of memory and execution time is used for the matrix solver; thus, improving matrix solver performance is a key to improve simulation performance. A χMD solver package was developed for higher robustness, faster execution speed, and better memory efficiency. The preconditioning module of χMD consists of level-based incomplete LU (ILU) factorization with a drop tolerance scheme that can reduce memory usage and lead to faster execution speed. The acceleration part consists of the conjugate gradient method, Bi-CGSTAB and ORTHOMIN. The χMD solver package is adapted for MODFLOW-2005 and preliminary results show that level-based ILU factorization with a drop tolerance scheme greatly reduce memory usage compared to ILU-only factorization by a factor of two or more. In addition, execution times decrease by 40% or more.Key words matrix solver; numerical modelling; groundwater


A GIS-linked unit response function approach to stochastic groundwater nonpoint source pollution modelling

GEORGE KOURAKOS, FRANK KLEIN & THOMAS HARTERDepartment of Land Air and Water Resources, University of California, Davis, California, [email protected]

Abstract A 3-D groundwater flow and transport modelling algorithm specifically designed for nonpoint source transport modelling is applied to a large groundwater sub-basin of the Central Valley, California, USA, to simulate and predict spatio-temporally distributed nitrate contamination over a century-long period. A simplistic domain decomposition method is proposed to simulate the velocity field (flow) at the decameter scale across a 2000 km2 domain. A streamline transport model is used to simulate the fate of contaminants and to link a large number (>103) of discrete discharge surfaces (production wells) with an even larger number (~104) of individual contaminant sources via unit response functions. Based on the historic and projected, spatio-temporally variable nitrate recharge history, nitrate output at wells is predicted via convolution of loading functions with unit response functions and integration across individual discharge surfaces. The results show that 45% of wells in this agricultural groundwater basin exceed the drinking limit in 2011, with an increase to 58% in 2050, despite

an assumed reduction of nitrate recharge rates after 2011.Key words nonpoint source modelling; streamline transport model; domain decomposition method; unit response functions; nitrate contamination; Central Valley, California


Visual preparation of hydrological models

KARSTEN RINK1, THOMAS FISCHER1, AGNES GRÄBE2 & OLAF KOLDITZ1,3

1 Department of Environmental Informatics, Helmholtz Centre for Environmental Research, Leipzig, [email protected] Department of Catchment Hydrology, Helmholtz-Centre for Environmental Research, Halle, Germany3 Department of Applied Environmental Systems Analysis, Technical University of Dresden, Germany

Abstract In this paper we demonstrate the functionality of the OpenGeoSys framework for visualisation of simulation-related data. Complex hydrological models are based on a large number of heterogeneous input data sets. In addition to any geo-scientific information such models also include finite element meshes, initial- and boundary conditions, and other data necessary for the simulation of hydrological processes. The visual assessment of this information in 3D space in the process of creating models has proven to be helpful for experts to attain a deeper understanding of the interrelation of data sets and the detection of possible problems or errors. The presented visualisation techniques are applied to a model region at the western Dead Sea escarpment for a simulation of groundwater recharge in an arid region.Key words visualisation; hydrology; simulation; groundwater flow


A 3D interpolation algorithm for layered tilted geological formations using an adapted inverse distance weighting approach

M. WALTHER, N. BÖTTCHER & R. LIEDLTechnische Universität Dresden, Institute for Groundwater Management, D-01062 Dresden, Germany

[email protected]

Abstract We present an algorithm for the 3D interpolation of layered tilted hydro-geological structures from point data. The method uses profile information and interpretations of the geological layering to interpolate discrete or continuous values in a meshed grid consisting of arbitrary element types. The user has the opportunity to tweak several options of the algorithm depending on the given application’s circumstances (e.g. data availability and reliability) and additional soft information of the geology. The interpolation algorithm is implemented in Qt and can be used as a pre-processing tool for mesh-based numerical methods (i.e. finite difference method, finite element method, finite volume method). Key words interpolation; 3D; pre-processing; inverse distance weighting; tilted; layered


Mixed 2D/3D visualization of a large scale groundwater study in a virtual reality centre

B. ZEHNER1, L. BILKE1, T. KALBACHER1, E. KALBUS2, K. RINK1,R. RAUSCH3 & O. KOLDITZ1

1 Department of Environmental Informatics, Helmholtz Centre for Environmental Research, Permoserstrasse 15, Leipzig, Germany [email protected], [email protected] Department of Hydrogeology, Helmholtz Centre for Environmental Research, Permoserstrasse 15, Leipzig, Germany

3 GIZ International Services, PO Box 2730, Riyadh 11461, Kingdom of Saudi Arabia

Abstract As part of a project which deals with a large-scale groundwater study aimed at simulating the available groundwater resources in the Upper Mega Aquifer system in the eastern part of Saudi Arabia, an interactive visualization has been created in order to show the simulation results, together with the original borehole data from which the input model was constructed and placed within the context of the geological surroundings in an easily understandable way. The 3D visualization can be run in a stereoscopic visualization centre and is augmented by additional 2D visualizations that help users to orient themselves within the virtual scenery and which also show additional information upon selection of corresponding objects in the 3D scene. Key words 2D; 3D; groundwater; visualization; virtual reality


Optimizing a long-term groundwater monitoring network using geostatistical methods

JAY KRISHNA THAKUR1, WOLFGANG GOSSEL1, HOLGER WEIẞ2 & PETER WYCISK1

1 Dept. of Hydrogeology and Environmental Geology, Institute of Geosciences and Geography, Martin Luther University, 06120 Halle (Saale), Germany [email protected] Dept. of Groundwater Remediation, Helmholtz-Centre for Environmental Research – UFZ, 04318 Leipzig, Germany

Abstract Groundwater long-term monitoring (LTM) is required to assess groundwater remediation and human health risk at sites with severe groundwater contamination. Groundwater LTM network optimization requires sampling at existing wells, data management, remediation, and risk reduction activities, costing millions of Euros. The study of monitoring network optimization was performed at a site in Eastern Germany using the geostatistical temporal spatial (GTS) algorithm in a 2.5D environment. The 2.5D environment assumes that there are multiple aquifers or hydrostratigraphic layers in the aquifer. An area of ~72 km 2 with 357 wells in the Tertiary aquifer and 462 wells in the Quaternary aquifer was selected. A dataset of the concentration of monochlorobenzine from October 2003 to December 2009 was obtained for optimizing the existing network. Local 3D geological and hydrogeological models were used to understand the spatial and temporal hydrogeological heterogeneity of the area. The optimal number and placement of wells in the existing network has been analysed for effective groundwater monitoring. Key words groundwater long-term monitoring network optimization; multiple objectives approach; geostatistical methods


Using streamlines for highly-resolved, reactive transport for CO2 leakage contamination in groundwater

ADAM L. ATCHLEY1,3, REED M. MAXWELL1,3, ALEXIS NAVARRE-SITCHLER2,3, ERICA R. SIIRLA1,3 & JOHN E McCRAY2

1 Department of Geology & Geological Engineering, 2 Environmental Science & Engineering Division, 3 Hydrological Science & Engineering, Colorado School of Mines, Golden, Colorado 80401, [email protected]

Abstract We present a Lagrangian streamline approach where a large, heterogeneous 3D flow field is reduced to a number of 1D transport simulations. The streamline approach allows the mapping of these 1D reactive transport simulations back onto a 3D flow field, thus accounting for spatial heterogeneity within the aquifer and complex aqueous geochemical processes. A CO2 leakage scenario from a hypothetical CCS site is used where a resulting plume of CO2 lowers the groundwater pH and mobilizes metals from an existing mineral host-rock distribution. The plume migration and related metal dissolution and precipitation within the aquifer were simulated using this streamline-geochemical modelling approach under varying hydrological heterogeneity variances (2

lnK). Results showed that heterogeneity significantly influences well contamination and geochemical processes.Key words reactive transport; uncertainty analysis; carbon capture and storage


Fate and transport modelling for monitored natural attenuation projects: what should be considered to maximise the value in decision making?

P. H. BECK & B. MANN GHD Pty. Ltd. Level 8, 180 Lonsdale Street, Melbourne, Victoria 3000, [email protected]

Abstract The Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) identified the need for the development of a technical guidance document on assessment, implementation and verification of Monitored Natural Attenuation at sites with residual dissolved phase hydrocarbon impact in groundwater. As part of the development process there was a need to include guidance on fate and transport modelling as there was a lack of relevant guidance in Australia and industry practice varied widely. One key consideration in the development of guidance was consideration of what value fate and transport modelling adds to the decision making process, and what standards the models need to meet to produce reliable results within acceptable bounds of uncertainty. The guidance document considered the key elements that should be included in any fate and transport model, and how these address uncertainties and provide transparency on reliability of modelling results for consideration by stakeholders and decision makers on the applicability of Monitored Natural Attenuation.Key words MNA; modelling; dissolved phase; guidance; uncertainty; Australia


Interpretation of hydrocarbon plume biodegradation in 2-D bench-scale tank experiments by reactive transport modelling

CHRISTOF BEYER1, ELISABETTA BALLARINI1, ROBERT D. BAUER2, CHRISTIAN GRIEBLER2, SEBASTIAN BAUER1

1 Institute of Geosciences, University of Kiel, Ludewig-Meyn-Str. 10, D-24118 Kiel, [email protected] Helmholtz Zentrum München, Institute of Groundwater Ecology, Ingolstaedter Landstr. 1, D-85764 Neuherberg, Germany

Abstract High resolution reactive transport modelling was applied as a tool for a model-based interpretation of detailed laboratory experiments on the interplay of transverse mixing and aerobic and anaerobic hydrocarbon biodegradation. As a typical groundwater contaminant, ethylbenzene (as a mixture of unlabelled and fully deuterium-labelled isotopologues) was continuously injected into a 2-D bench-scale flow-through tank through a central inlet port, generating a hydrocarbon plume along the whole length of the tank. During the first phase of

the experiment, where the tank was recharged with water containing oxygen as the major dissolved electron acceptor, the aerobic strain Pseudomonas putida F1 was inoculated in order to initiate aerobic biodegradation of the ethylbenzene. Later, nitrate was added as an additional electron acceptor and the denitrifying strain Aromatoleum aromaticum EbN1 was inoculated to study competitive degradation under aerobic / anaerobic conditions. The spatial distribution of anaerobic degradation was investigated using measurements of compound-specific stable isotope fractionation along a vertical profile at the tank outlet. The numerical model was calibrated to fit the measured concentration profiles of these compounds at the outlet ports. Simulated and measured ethylbenzene and oxygen concentrations showed a good agreement for the aerobic degradation phase of the experiment, while the evaluation of the aerobic/anaerobic phase with competitive biodegradation was ambiguous due to uncertainties regarding the actual stoichiometry of the specific denitrification reaction. The model results, calibrated on the stable isotope signatures, showed that for the case of aerobic/anaerobic degradation the observed isotopic pattern strongly depends on the assumed initial distribution of microbial biomass.Key words hydrocarbon biodegradation; isotope fractionation; numerical modelling; transverse dispersion


Compound-specific local and effective transverse dispersion coefficients for conservative and reactive mixing in heterogeneous porous media

GABRIELE CHIOGNA1,2, OLAF A. CIRPKA2, PETER GRATHWOHL2 & MASSIMO ROLLE2

1 University of Trento,Dipartimento di Ingegneria Civile ed Ambientale, via Mesiano 77, I-38123 Trento, [email protected] University of Tübingen,Center for Applied Geosciences, Sigwartstr. 10, D-72076 Tübingen, Germany

Abstract Dilution in heterogeneous porous media can be quantified using different measures which lead to the definition of effective dispersion coefficients. These up-scaled parameters should account for both local-scale dispersion and effects of flow variability in heterogeneous formations (e.g. flow focusing in high- conductivity and defocusing in low-conductivity inclusions). The correct quantification of mixing is particularly important in order to model mixing-controlled reactions in porous media. Under steady-state conditions with continuous injection from a line source, 2D conservative and reactive solute transport simulations were performed. It was shown that different parameterizations of local transverse dispersion coefficients significantly affect the quantification of field-scale mixing processes. Bench-scale experiments showed a nonlinear dependence of local transverse dispersion on molecular diffusion over a wide range of flow velocities, implying compound-specific transverse mixing at the local Darcy scale. Heterogeneous field-scale scenarios were considered, characterized by different variability in the conductivity field, and a set of Monte Carlo simulations was performed. We quantified transverse mixing with different measures including effective transverse dispersion coefficients, scalar dissipation rates and the recently introduced flux-related dilution index and flux-related second central spatial moments. It was shown that quantities derived in a flux-related framework are affected by a lower degree of uncertainty and that, in the case of low to moderately heterogeneous porous media, the effective transverse dispersion coefficients are significantly different for different compounds. Effective transverse dispersion coefficients were found to be up to one order of magnitude larger than the local values due to mixing enhancement processes related to flow-focusing in high-permeability inclusions. In the case of mixing-controlled reactive transport, considering instantaneous complete bimolecular reactions, it was shown that compound-specific dispersion coefficients affect the prediction of the length of reactive solute plumes. Furthermore, the recently developed concept of critical dilution index was applied to quantify the amount of mixing required to completely degrade a reactive contaminant plume.Key words mixing; transverse dispersion; dilution index


Reactive transport simulation of volatile organic compound

removal in vertical flow soil filters

CECILIA DE BIASE1,2, ULI MAIER3, SASCHA OSWALD4 & MARTIN THULLNER1

1 Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany [email protected] Department of Groundwater Remediation, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany 3 Center for Applied Geosciences, University of Tübingen, Germany 4 Institute of Earth and Environmental Sciences, University of Potsdam, Germany

Abstract Vertical flow soil filters are an emerging technology for the treatment of groundwater contaminated with volatile organic carbon compounds. These filters are characterized by unsaturated flow conditions and high contaminant removal rates, but for the assessment of their remediation efficiency a sound distinction between biodegradation and volatilization is crucial. In this study, a vertical flow soil filter system exposed to intermittent feeding of contaminated groundwater leading to a highly transient flow pattern was simulated using the numerical model MIN3P. Simulated processes include (besides other reactions) the microbial degradation of aqueous species as well as their volatilization and advective-diffusive transport in the water phase and the soil air phase. Flow and transport processes were calibrated using measured field data and the model subsequently used to describe the removal of ammonium and two volatile organic contaminants – benzene and MTBE. Model results confirm experimentally observed high removal rates and show that both removal processes – biodegradation and volatilization – have the potential to significantly contribute to such removal. The contribution of each process depends on the design and operation of the filter system, the hydraulic properties of the filter material, and the degradation capacity of the microbial population. If these factors are sufficiently well combined volatile emissions can be avoided and observed contaminant removal can be nearly all attributed to biodegradation.Key words reactive transport modelling; volatile organic compounds; unsaturated zone; groundwater remediation; biodegradation


The relation between pore-scale heterogeneity, bioavailability and bacterial mobility: a numerical modelling approach

M. GHARASOO, F. CENTLER, I. FETZER & M. THULLNERDepartment of Environmental Microbiology, UFZ – Helmholtz Centre for Environmental Research, Leipzig, [email protected]

Abstract Desirable reactive subsurface processes, e.g. nutrient cycling or degradation of organic contaminants, are driven by microorganisms populating the soil matrix. These environments are characterized by heterogeneities at various scales which influence the transport of chemical species and the spatial distribution of microorganisms. As a result, the biodegradation rate of contaminants at large scales does not only depend on the degradation capacity of the indigenous microbial population, but also on their distribution patterns and the heterogeneities of the hosting media. Many of these organisms are motile and exhibit a chemotactic behaviour driven by gradients of substrate and fellow organisms. In this study, we developed a reactive transport pore-network model to study the bioavailability effects resulting from structural heterogeneity of the pore space. Then, we included an individual-based modelling approach to simulate the bacterial pattern conformation in heterogeneous porous media. By varying the degree of structural heterogeneities or the chemotactic sensitivities of the bacteria, we explored how the degradation performance is affected and what population distributions emerge.Key words individual-based modelling; pore network model; bioavailability; reactive transport model; spatial distributions; pore-scale heterogeneity; microbial patterns


Modelling reactive transport of chlorinated hydrocarbons in groundwater under spatially varying redox conditions

T. GREIS1, K. HELMHOLZ2, M.H. SCHÖNIGER2 & A. HAARSTRICK3

1 Institute of Biochemical Engineering, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, [email protected] Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany3 Institute of Geoecology, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany

Abstract Chlorinated ethene degradation in groundwater has proven to be highly dependent on environmental conditions. Nevertheless, literature dealing with the interaction between chlorinated ethene degradation and inorganic electron acceptors such as nitrate is scarce. A study area located in Braunschweig (Germany), where redox conditions vary from nitrate-reducing to iron(III)-reducing conditions, is utilised for validation of a reactive transport model. A groundwater model using conventional 1st-order degradation kinetics, which was additionally optimised via sequential Monte-Carlo simulations, could not satisfactorily describe the pollutant distribution of the site. Thus, laboratory experiments considering the influence of inorganic electron acceptors were used to formulate enhanced inhibition kinetics that were implemented into the field scale model. The results yield a better accordance of simulated and measured concentration data than applying the previous 1st-order kinetics.Key words DNAPL pollution; modelling; reactive transport


Reactive transport modelling of weathering processes in intensely stratified mine tailings

J. A. MEIMA1, D. RAMMLMAIR1 & M. REDWAN1,2

1 Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Stilleweg 2, 30655 Hannover, [email protected] Geology Dep., Faculty of Science, Sohag University, 82524 Sohag, Egypt

Abstract Reactive transport simulations have been applied to investigate possible effects of stratification on the potential of sulfide-bearing mine tailings to form protective cemented layers and to retain toxic elements. Our research is based on a German tailings site, where material is intensely stratified on a mm-cm scale. The computational domain was defined as an one dimensional column the size of a microscopic thin section of 22 mm length. Detailed quantitative information on changes in mineralogical composition was obtained by mineral liberation analysis (MLA). The resulting reactive transport model was applied to simulate Acid-Rock-Drainage (ARD) formation, the interaction of ARD with the tailings sediment, the formation of cemented layers, and the fate of arsenic, zinc, and lead. The results show that the identity and spatial distribution of weathering products is strongly dependent on local variations in the primary mineral assemblage.Key words reactive transport modelling; mine tailings; mineral liberation analysis; weathering; cemented layers; metal retention; unsaturated zone


Importance of thermal dispersion in temperature plumes

NELSON MOLINA-GIRALDO1, PHILIPP BLUM2 & PETER BAYER3

1 University of Tübingen, Center for Applied Geoscience (ZAG), Sigwartstraße 10, 72076 Tübingen, [email protected]



2 Karlsruhe Institute of Technology (KIT), Institute for Applied Geosciences (AGW), Kaiserstraße 12, 76131 Karlsruhe, Germany3 ETH Zürich, Engineering Geology, Sonneggstrasse 5, 8092 Zurich, Switzerland

Abstract The objective of this study is to evaluate the influence of thermal dispersion on the simulation of temperature plumes that evolve from the application of vertical ground source heat pump (GSHP) systems in aquifers. Various hydrogeological scenarios are simulated with longitudinal dispersivity ranging between 0.5 and 2 m and a Darcy velocity between 10-8 m s-1 and 10-5 m s-1. In addition, thermal dispersivity is assumed to be scale-dependent. Based on a field scale of 10 m, the study shows that the thermal dispersion is an important factor for the prediction of shape and extension of temperature plumes in medium-grained sand to gravel aquifers. From the perspective of environmental regulators, such assumptions might be crucial for licensing applications of neighbouring GSHP systems. In contrast, ignoring thermal dispersion provides appropriate predictions of the temperature plume length for hydrogeological conditions dominated by fine sands, silts and clays. Key words thermal dispersivity; analytical solution; ground source heat pump system; temperature plume


A flexible approach for coupled reactive transport modelling in post-mining areas

MIKE MÜLLER1 & HEIKE BÜTTCHER2

1 Hydrocomputing UG (haftungsbeschränkt) & Co. KG, Zur Schule 20, D-04158 Leipzig, [email protected] Ingenieurbüro für Grundwasser GmbH, Nonnenstr. 9. D-04229 Leipzig, Germany

Abstract The River Pleiße flows through the dump of the open pit lignite mine Witznitz close to Leipzig, Germany, and is impacted by discharging groundwater with high iron concentrations. A two-dimensional (2D) reactive transport model was set up based on an existing 3D model and an extensive study of dump development. A new template-based tool for reactive transport was developed, giving the modeller great flexibility without the need for programming. Primary and secondary iron oxidation, as well as dissolution, precipitation and exchange processes, were modelled. A comparison of modelled and measured values shows a good correspondence, indicating that the model can represent the important processes. Modelling results show the influence of spatial variability and provide quantitative results for long-term water quality developments in the subsurface and fluxes to the river. The newly developed modelling tool can be used for a variety of hydogeochemical problems.Key words water; rivers; groundwater; River Pleiße, Germany; PCGEOFIM; PHREEQC; coupled modelling


Evaluating effective reaction rates of kinetically driven solutes in large-scale, anisotropic media: human health risk implications

ERICA R. SIIRILA & REED M. MAXWELLDept. of Geology and Geological Engineering, Colorado School of Mines, 1500 Illinois St., Golden, Colorado 80401, USA [email protected]

Abstract The role of high and low hydraulic conductivity regions in heterogeneous, stratified flow fields and the subsequent effect of rate dependent geochemical reactions are investigated. Human health risk (cancer) is used as an endpoint for comparison via a two-stage nested Monte Carlo scheme, explicitly considering joint uncertainty and variability. Parameter interplay is investigated using stochastic ensembles. This study identifies the effect of geo-hydrologic conditions on solute equilibrium and the effect of preferential flow pathways and mixing at the field and local scales for varying degrees of stratification. Results show effective reaction rates of kinetic ensembles are dissimilar from equilibrium ensembles with local dispersion, resulting in an additive tailing effect of

the solute plume, a retarded peak time, and an increased risk. Uncertainty in risk is also controlled by these factors. We demonstrate that a higher associated uncertainty of risk in stratified domains is linked to higher aquifer connectivity and less macrodispersion.Key words cancer risk; kinetic sorption; local dispersion; stochastic Monte Carlo; CO2 leakage; arsenic


Mixing processes in highly heterogeneous formations

FRANCESCA BOSO & ALBERTO BELLINDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Trento, [email protected]

Abstract We numerically explored the interplay between formation heterogeneity and local dispersion on the transport of a passive tracer in highly heterogeneous formations. In order to minimize the negative impact of numerical diffusion, we used the Smoothed Particle Hydrodynamics scheme recently proposed by Herrera et al. (2009). Heterogeneity enhances mixing, as measured by the dilution index, with a rate of increase with the logtransmissivity variance that attenuates passing from moderately to highly heterogeneous formations. In addition, the sample frequency distribution of the solute concentration is well represented by a Beta model at both low and high variances. The Beta model requires the knowledge of the spatial mean and variance of the solute concentration as the only parameters to be determined. Key words mixing; highly heterogeneous formations; concentration distribution


A multidisciplinary study of sediments’ connectivity and transport parameters for aquifer analogues

MAURO GIUDICI1, RICCARDO BERSEZIO3, FABRIZIO FELLETTI3, FULVIA BARATELLI1,2, LAURA CATTANEO1, EMMANUELE CAVALLI3, DIANA DELL’ARCIPRETE1, MAURO MELE3, LORENZO PESSINA3 & CHIARA VASSENA1

1 Università degli Studi di Milano, Dipartimento di Scienze della Terra “A. Desio”, via Cicognara 7, 20129 Milano, [email protected] Università degli Studi di Milano, Dipartimento di Fisica, via Celoria 16, 20133 Milano, Italy3 Università degli Studi di Milano, Dipartimento di Scienze della Terra “A. Desio”, via Mangiagalli 34, 20133 Milano, Italy

Abstract A multidisciplinary approach is applied to the study of aquifer analogues, i.e. outcrops of geological structures which can be easily investigated and which resemble the buried aquifers. The application of this approach to some cases selected to represent typical structures of the alluvial aquifers in the Po Plain (northern Italy) shows the importance of joining field work (sedimentological, petrographical, geophysical, hydrological) with stochastic simulation, modelling tools and connectivity analysis. The final goal of this research programme is to enhance the match between the heterogeneity of hydrofacies at a fine scale and the behaviour of flow and transport at a large scale.Key words groundwater; aquifer analogues; alluvial aquifers; hydrostratigraphy; mathematical modelling; geostatistical simulations; connectivity


Analysis of time-drawdown data from heterogeneous leaky aquifer systems

CAGRI GOKDEMIR1, NADIM K COPTY1, MATTHEW WATERMAN2 & ANGELOS N FINDIKAKIS2

1 Institute of Environmental Sciences, Bogazici University, Bebek, Istanbul, [email protected] Bechtel National Inc., San Francisco, California, USA

Abstract The analysis of drawdown data from pumping tests is often performed using graphical techniques that are based on the assumption of aquifer homogeneity. However, natural subsurface formations are heterogeneous with complex patterns of spatial variability. In this paper, we describe a novel interpretation method that uses the time derivative of the drawdown to infer information about the spatial variability of the flow parameters in heterogeneous leaky aquifer systems. The method uses the observed drawdown and its time-derivative at a single point to estimate the hydraulic parameters. By applying the procedure to different portions of the time-drawdown data, variations in the flow parameters with radial distance from the pumping well are detected. The method can also be used as a tool to identify the type of aquifer system present. For demonstration the method is applied to pumping test data from an alluvial leaky aquifer in California, USA. Various data smoothing and differentiation techniques were evaluated for the estimation of the time-drawdown derivative. Because of the noise typically observed in field data, optimal estimates of the drawdown derivative were obtained by first fitting the drawdown data to high order polynomials and splines and then differentiating the fitted functions with respect to time. Results of the analyses show that the proposed methodology is a viable tool for the interpretation of pumping test data and that it may yield important information about the heterogeneity of the aquifer, which is generally ignored in conventional pumping test analysis techniques.Key words well hydraulics; analysis of pumping test; groundwater flow modelling; heterogeneity; transmissivity; leaky aquifers


Generating land-use information to derive diffuse water and nitrate transfer at aquifer scale

GERNOT KLAMMLER, GERHARD ROCK, HANS KUPFERSBERGER & JOHANN FANKJOANNEUM RESEARCH Forschungsgesellschaft Graz, RESOURCES – Institute of Water, Energy and Sustainability, Elisabethstraße 16/II, Water Resources Management, A-8010 Graz, [email protected]

Abstract Modelling diffuse water and nitrate transfer in the unsaturated zone is a state-of-the-art method for determining groundwater recharge and nitrogen leaching at aquifer scale, which can be used to define the upper boundary condition for transient groundwater flow and transport models. Together with soil and weather data, land-use information is an indispensable input parameter for modelling groundwater recharge and nitrogen leaching, but is not available in detail at aquifer scale. In Austria, information concerning cultivated crops is only available as annual crop percentages on the aggregated level of cadastral municipalities. To deal with this problem a stochastic crop rotation tool StotraPGen is developed which uses multiple crop rotations and derives optimal percentages of characteristic crop rotations for representing the statistical land-use data. To validate the approach of StotraPGen the agricultural research site Wagna (Austria) is treated as a single cadastral municipality. Based on the exact land-use knowledge, annual crop percentages (as it is available at aquifer scale) are computed for the period 1988–2009. In a next step, the time series of groundwater recharge and nitrate leaching are simulated using (a) the actually applied crops and fertilizers, (b) the stochastic land-use approach StotraPGen and (c) using just one single crop rotation. The comparison of the results shows that StotraPGen very closely resembles the simulated unsaturated zone response due to the real agricultural land-use. Using one single crop rotation does not yield satisfying groundwater recharge and nitrogen leaching results on a daily basis. Future work will focus on upscaling uncertainties due to insufficient soil depth information at aquifer scale, and iterative coupling between saturated and unsaturated water flow and solute transport models to improve the representation of the saturated–unsaturated interface in future model simulations.

Key words vadose/unsaturated zone; diffuse water and nitrate transfer; groundwater recharge; nitrate/nitrogen leaching; land-use; modelling; aquifer/regional scale, multiple crop rotation


Investigation of large-scale pressure propagation and monitoring for CO2 injection using a real site model

KATHARINA BENISCH & SEBASTIAN BAUERInstitute for Geosciences, University of Kiel, Ludewig-Meyn-Str. 10, D-24118 Kiel, Germanyk b @ g p i .un i - k iel. d e

Abstract This paper presents a study on monitoring of large-scale pressure evolution during and after CO2 injection on a real site-scale model in the North German Basin. The study is aimed at identifying suitable locations for monitoring and at determining the conditions under which meaningful pressure signals can be measured. A multi-layered reservoir model is used, which contains two potential storage formations separated by a cap rock complex. CO2 is injected into the lower storage formation. The pressure is monitored in several geological layers at varying distances from the injection well. Simulation results show that pressure increases both in the cap rock and below the storage formation. The pressure increase in the upper storage formation is only faintly detectable, so that no interaction between the two storage formations has to be expected. The type of boundary conditions used yield changes in the pressure signal at larger distances from the injection well, but not close to it. These results show that pressure monitoring and assessment is sensitive to individual site conditions and site geology, and has to be evaluated for each CCS project individually.Key words CO2 injection; monitoring; pressure propagation


Comparison of equations of state for carbon dioxide for numerical simulations

NORBERT BÖTTCHER1, JOSHUA TARON2, OLAF KOLDITZ1,2, RUDOLF LIEDL1 & CHAN-HEE PARK3

1 Technische Universität Dresden, Helmholtzstr. 10, 01062 Dresden, [email protected] Helmholtz-Centre for Environmental Research – UFZ, Permoserstr. 15, 04318 Leipzig, Germany3 Korea Institute of Geoscience and Mineral Resources (KIGAM), 124 Gwahang-no, Yuseong-gu, Daejeon 305-350, Korea

Abstract In this work, we compare four equations of state for carbon dioxide with a large number of measurement data taken from literature. This comparison showed that complex equations of state are more accurate than simple ones. To see if the differences in accuracy have an influence on numerical simulations, we implemented the equations in the scientific software OpenGeoSys and performed comparative simulations of a compressible gas flow scenario. We found out that the difference between ideal gas and real gas behaviour is quite large, but the differences among the real gas equations have no significant influence on the simulation results. Key words equation of state; compressible fluid flow; carbon dioxide; numerical simulation; gas storage; supercritical fluid


The coupled multiphase flow and reactive transport simulator OGS-Eclipse for CO2 storage simulations

BASTIAN J. GRAUPNER1,2, DEDONG LI1, KATHARINA BENISCH1, ADDISALEM BITEW MITIKU1, CHRISTOF BEYER1 & SEBASTIAN BAUER1

1 Institute of Geosciences, University of Kiel, Ludewig-Meyn-Str. 10, 24118 Kiel, Germany2 Now at: Eidgenössisches Nuklearsicherheitsinspektorat ENSI, Industriestrasse 19, CH-5200 Brugg, [email protected]

Abstract The long-term prognosis of the behaviour of CO2 injected into the subsurface is of relevance for risk assessment and reservoir management. Due to the coupled multiphase flow and reactive transport processes interacting in the subsurface, adequate numerical methods are required for a reliable simulation. This work presents the scientific open source software OpenGeoSys, which was coupled to the standard multiphase flow simulator Eclipse. Eclipse provides a fast and reliable numerical solution to the multiphase flow problem, whereas OpenGeoSys is used for simulating component transport and geochemical reactions. This paper shows the code structure and verifies the coupled code by a number of benchmark simulations. The applicability to real site conditions is shown using data for a typical site in the North German Basin.Key words multi phase flow; reactive transport; CO2 storage, saline aquifer


Harnessing the complex behaviour of ultra-dense and viscous treatment fluids as a strategy for aquifer remediation

UTKU SOLPUKER1, JARED HAWKINS1, ROBERT SCHINCARIOL2, MOTOMU IBARAKI1 & FRANKLIN W. SCHWARTZ1

1 School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, [email protected] Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada N6A 5B7

Abstract This paper examines the possibility of harnessing variable density flow and other processes in the delivery of KMnO4. Specifically, we examined remediating chlorinated solvents as plumes in contaminated aquifers using a semi-passive barrier approach. It is necessary to predict how solutions behave once they are injected into the aquifer. Flow and transport are investigated through experimental and modelling studies. The experimental work of Schincariol and Schwartz is modelled using a finite element code MITSU3D. Simulations revealed that lenses with different permeability enhance mixing and relatively low permeability lenses have the potential to sequester the dense fluids. MITSU3D code is adjusted to simulate the variable density flow of viscous silicate solutions. Fingering in such a heterogeneous system appears to be relatively unimportant. Other possibilities for sequestering KMnO4 at the site of emplacement include increasing the viscosity and forming gels. Dilute silicate solutions can turn into gel through time when they are mixed with dilute bicarbonate solutions. With the addition of permanganate, this gel can act as a slow-release material. Key words variable density flow; silicate solutions; MITSU3D; time-delayed gelling; slow release material


Simulation of flow in fractured rocks using effective stress-dependent parameters and aquifer consolidation

GIONA PREISIG1, FABIEN J. CORNATON2 & PIERRE PERROCHET1

1 Centre for Hydrogeology and Geothermics, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, [email protected]

2 DHI-WASY GmbH, Waltersdorfer Straße 105, 12526 Berlin, Germany

Abstract Effective stress plays an important role in aquifer dynamics, especially in those affected by high variations of water pressures. Increasing/decreasing effective stresses affect hydrogeological parameters, even in media of high stiffness, such as fractured rocks. This study presents a modelling approach of groundwater flow in fractured rocks and aquifer deformation taking into account the dependency of hydrogeological parameters on effective stress. This approach has been illustrated by modelling a fractured aquifer dynamic, the Zeuzier arch dam settlement. The calibrated model showed agreement with measured data. This simulation method could be used to study the sensitivity of aquifers to variations in effective stress due to water pressure.Key words numerical modelling; effective stress; fracture permeability; fractured aquifers consolidation; Zeuzier


Modes of free convective flow in fractured-porous rock

KATHARINA VUJEVIĆ & THOMAS GRAFInstitute of Fluid Mechanics and Environmental Physics in Civil Engineering, Leibniz Universität Hannover, Appelstr. 9A, 30167 Hannover, [email protected]

Abstract The effect of regular orthogonal fracture networks on density dependent free convection is investigated by numerical simulations. Discrete orthogonal fracture networks of different fracture spacing are systematically added to the Horton-Rogers-Lapwood (HRL) problem for free-convective flow in unfractured homogeneous porous rock. The equivalent hydraulic conductivity was preserved when fractures were added. Simulation results suggest that fractures affect free-convective flow if: (i) fracture permeability is more than five orders of magnitude larger than matrix permeability, and if (ii) fracture spacing is large. With decreasing fracture spacing, flow patterns approximate those of the corresponding unfractured HRL problem. Furthermore, a diffusion-only case at low Rayleigh number in homogeneous unfractured rock is regarded. It is shown that adding few fractures with large fracture spacing promotes free convective flow compared to the unfractured case of the same equivalent permeability.Key words groundwater; fractures; Rayleigh; density; HydroGeoSphere; numerical modelling


Determination of thermodynamics in a CO2 injection well using pressure and distributed temperature sensing

B. WIESE1, M. NIMTZ2, F. MÖLLER1, C. OTTO1, M. KÜHN1, A. LIEBSCHER1 & C. SCHMIDT-HATTENBERGER1

1 German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, [email protected] Power Plant Technology, BTU Cottbus, Walther-Pauer-Straße 5, 03046 Cottbus, Germany

Abstract The injection of CO2 into the subsurface at the Ketzin pilot site, Brandenburg (Germany), is monitored simultaneously by distributed temperature sensing (DTS) and two pressure sensors located at the wellhead and at 550 m depth. The data is used to recalculate a continuous pressure profile along the entire length of the injection well. The data allow calculation of the thermodynamic properties of the CO2 inside the injection well, as well as potential phase transitions during the injection process. Due to compression a heat flux establishes between the injection well and the subsurface that can be quantified based on the thermodynamic state. Key words CO2; injection; distributed temperature sensing; heat flux


Coastal aquifer management under drought conditions considering aquifer spatial variability

V. CHRISTELIS, G. KOPSIAFTIS & A. MANTOGLOUNational Technical University of Athens, School of Rural and Surveying Engineering, Laboratory of Reclamation Works & Water Resources Management, Heroon Polytechniou 9, 15780 Zografou, Greece [email protected]

Abstract The problem of pumping optimization of coastal unconfined aquifers is investigated. The Sequential Quadratic Programming (SQP) optimization method is combined with a numerical flow model based on the sharp interface assumption and Ghyben-Herzberg approximation. The objective is to maximize the total pumping rate, considering aquifer spatial variability and drought conditions due to climate changes, while protecting the aquifer from seawater intrusion. Using Monte-Carlo simulation, optimal pumping rates were calculated for different statistical properties of hydraulic conductivity and for various drought recharge scenarios. The results indicate that the maximum allowed pumping rates are significantly affected by the variance and correlation length of hydraulic conductivity random fields while recharge reduction leads to a significant reduction of maximum pumping.Key words groundwater; seawater intrusion; Monte-Carlo


Impact of long-term changes in climate on groundwater resources in an arid setting

IRINA ENGELHARDT1 & KERSTIN PRÖMMEL2

1 Technical University of Darmstadt, Institute of Applied Geosciences, Schnittspahnstrasse 9, 64287 Darmstadt,[email protected] Freie Universität Berlin, Institute of Meteorology, Carl-Heinrich-Becker-Weg 6-10, 12165 Berlin, Germany

Abstract Scenarios of shifts in climate calculated until 2200 were coupled with a groundwater model within an arid setting. Precipitation calculated by the climate model is converted to groundwater recharge, which is supposed to decrease by 45% during the next 200 years. Population growth models determine pumping rates of groundwater wells for human freshwater demand. Groundwater level decline and budgets are calculated for four greenhouse gas emission scenarios and for two population growth rate scenarios, respectively. Groundwater levels decline by up to 100 m until 2200 if a medium population growth scenario is assumed. However, if population grows with a smaller increase rate, a depletion of the aquifer may be prevented and a balance between in- and outflow can be reached again. Changes in climate have only a minor impact on the groundwater budget compared to human freshwater demand, emphasizing the importance of introducing new technologies to reduce water consumption in an arid environment in future.Key words arid hydrology; climate change; groundwater management; population model; climate model; CO2 emission


Simulation and prognosis of the impacts of climate changes on groundwater recharge under local conditions

ISSA HASAN, JANA SALLWEY, ULRIKE HAFERKORN & PETER-WOLFGANG GRAEBER

Technische Universitaet Dresden/ Institute of Waste Management and Contaminated Site Treatment, Pratzschwitzer Strasse 15, 01796 Pirna/ [email protected]

Abstract Climate changes mainly occur to the Earth’s temperature and precipitation, which increase water resources stress in many regions. The purpose of this study was to simulate the effects of potential climate changes, especially the changes of temperature and precipitation intensity, on groundwater recharge rate, because the infiltration rate is influenced by hydraulic conductivity, current water content, properties and texture of the soil, through implementation of different scenarios using the simulation program PCSiWaPro® which is combined with a stochastic weather generator (WettGen). Precipitation and evapotranspiration of the soil-plant system are considered in the program as source and sink of water balance. The simulation results using PCSiWaPro® indicate the role of land use and land cover on groundwater recharge rate. The initial and boundary conditions of the models are crucial in the simulation results. In general, the results show an increased surface runoff, which leads to a decreased groundwater recharge.Key words groundwater recharge; climate changes; water balance; numerical methods; transient simulation


Climate and land-use change impacts on groundwater recharge

BERTRAND LETERME1 & DIRK MALLANTS2

1 Performance Assessment Unit, SCK•CEN, Boeretang 200, 2400 Mol, [email protected] CSIRO Land and Water, Waite Campus, Urrbrae 5064 SA, Australia

Abstract We show the effects of both climate and land-use changes on long-term groundwater recharge. The study was conducted in the context of a safety assessment of a near-surface disposal facility for low and intermediate level waste; this includes estimating groundwater recharge for the next millenia. Climate change impact on groundwater recharge was simulated using HYDRUS-1D and weather time series from so-called analogue stations. Results showed that transition to a warmer climate is expected to yield a decrease in groundwater recharge. For land-use change impact on groundwater recharge in the Nete catchment, conversion to crop (maize) and coniferous forest resulted in the highest positive (recharge increase by 30%) and negative (recharge decrease by 41%) sensitivities, respectively. Further improvements of the method may consider correlation and feedback between combined land-use change and climate change.Key words groundwater recharge; climate change; land-use change; Nete catchment, Belgium


What are the key parameters for soil hydrological models in climate impact studies under different settings?

J. PALM1, H. STÖFEN1, W. H. M. DUIJNISVELD2 & W. SCHNEIDER1 1 Institute for Water Resources and Water Supply, Hamburg University of Technology, Hamburg, Germany

[email protected] Department of Groundwater and Soil Science Federal Institute for Geosciences and Natural Resources, Hannover, Germany

Abstract As climate models become more and more accurate and climate change becomes less deniable, a demand for applications of various impact models grows stronger. The impact on groundwater budget is often calculated by numerical models, such as SWAP and HYDRUS, using the Penman-Monteith-equation for potential and actual evapotranspiration and the Richards equation (using van Genuchten-Mualem-parameter) for water movement in the vadose zone. On the one hand, using such a detailed model has the advantage to identify seasonal shiftings in the soil water budget; on the other hand applying those models to the meso-scale has the drawback of a high data demand. To show whether an impact model is reliable enough to explain the impact of

climate change on the target parameter (e.g. groundwater recharge) its sensitivity to parameter variation has to be tested. Sensitivity studies can also indicate which parameters can be neglected and which need to be investigated in more detail. Two calibrated SWAP models have been applied to estimate the impact of climate change on the water budget for an upland and a polder location. While the first site is a typical groundwater recharge area, the latter is a ditch-drained area where permanent groundwater discharge occurs. For both sites, climate projections from two regional climate models (CLM and REMO) driven by the general circulation model ECHAM5 have been used. The results from two realizations of the SRES CO2-scenarios A1B, B1 and A2 as well as the C20 reference period were available. Instead of using the data directly, two different bias correction methods were applied: a linear bias correction method and the so-called quantile mapping method. The Cramér-von Mises criterion has been applied to show which method is applicable for each site. Afterwards, two sensitivity tests were conducted. The Model-Scenario-Ratio (MSR) has been applied to identify the effect of parameter uncertainty on the relative impact of climate change on the oil water budget. The Scenario-Uncertainty-Ratio (SUR), which we adapted from the MSR, identifies whether the impact of the parameter uncertainty or the climate change impact is stronger. As a result we see that different hydrological settings show different parameters to be sensitive in terms of water budget. While crop and meteorological parameters are sensitive for the upland site, soil and drainage parameters are shown to be more important for the polder site. The study shows that process-oriented model-codes can be applied to meso-scale, if an appropriate sensitivity study is carried out to identify parameters that can be neglected for regionalization. Key words climate change impact assessment; SWAP; groundwater recharge; BIAS correction methods; sensitivity


Wind energy forecast ensembles using a fully-coupled groundwater to atmosphere model

JOHN L. WILLIAMS, III1 & REED M. MAXWELL1,2

1 Colorado School of Mines, Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, 1500 Illinois St, Golden, Colorado 80401, [email protected] Integrated Groundwater Modeling Center, 1500 Illinois St, Golden, Colorado 80401, USA

Abstract As wind energy becomes an increasingly important component in the renewable energy portfolio, accurate wind forecasts become critical. We apply the PF.WRF model, a fully-coupled groundwater-to-atmosphere model incorporating the parallel three-dimensional variably-saturated hydrologic model ParFlow and the Weather Research and Forecasting (WRF) atmospheric model to simulate the components of the hydrologic cycle from bedrock to the top of the atmosphere. Model components are coupled via moisture and energy fluxes in the Noah Land Surface Model. The fully-coupled model dynamically simulates important meteorological effects of interactions between the land surface and the atmosphere, controlled in part by soil moisture distribution and land surface energy flux partitioning. In this study, we complete ensemble simulations for three wind ramping events at a wind energy production site on the west coast of North America using varying stochastic random fields of subsurface hydraulic conductivity and forced with meteorological data from the North American Regional Reanalysis dataset for a series of wind ramp events. We attribute error between the modelled and observed data to uncertainty in the statistical representation of subsurface heterogeneity and errors in boundary condition forcing data. Key words land–surface atmosphere feedbacks; uncertainty; heterogeneity; wind; wind energy; weather forecasting


Flow in the unsaturated zone to quantify Acid Mine Drainage: numerical and analytical approaches

MARTÍ BAYER-RAICH & SALVADOR JORDANA Amphos21, Passeig de Garcia i Faria 49-51 1-1, 08019. Barcelona, Spainmarti.bayer @amphos21.com

Abstract We study flow conditions in the unsaturated zone to quantify Acid Mine Drainage (AMD) in mine-waste piles using the van Genuchten model. Both analytical and numerical methods are applied to estimate the fundamental variables governing flow in the unsaturated zone: water saturation, water velocity (i.e. travel times), Darcy velocity, water pressure and head. We use numerical solutions, obtained with the code MIN3P to estimate saturation and travel times in multi-layered systems, for three hypothetical scenarios. A simple, novel analytical approach is developed for vertical flow in homogeneous media to obtain order-of-magnitude estimates of saturation and water velocity. This solution is applied to the hypothetical scenarios and shows that variability of hydraulic conductivity (up to four orders of magnitude) has little effect on travel times.Key words vadose zone; mine-waste piles; unsaturated flow; groundwater


Development of the hourly hydrological model for mountainous basins using the storage function method and the Diskin-Nazimov infiltration model

KAZUMASA FUJIMURA1, KIYOHARA SHIRAHA2, SHINJIRO KANAE2 & MASAHIRO MURAKAMI3

1 Department of Interdisciplinary Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, [email protected] Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan3 School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-gun, Kochi 782-8502, Japan

Abstract This study aims to improve the daily hydrological model to an hourly hydrological model by combining the storage function method, the Diskin-Nazimov infiltration model and the groundwater recharge and runoff calculation procedure. The hourly hydrological model in this study was evaluated by estimating the runoff in the Sameura Dam basin (472 km2), located in the mountains of Shikoku in western Japan, using 16 years series of hydrological rainfall data. The results indicated satisfactory to good model performance in terms of obtaining an accurate monthly mean hydrograph as well as daily and hourly mean hydrographs.Key words hourly hydrological modelling; 50 m-resolution DEM; Diskin-Nazimov infiltration model; groundwater and surface runoff


Development of a regional groundwater flow model along the western Dead Sea escarpment

AGNES GRÄBE 1,3, TINO RÖDIGER1, KARSTEN RINK2, THOMAS FISCHER2 & OLAF KOLDITZ2,3

1 Helmholtz Centre for Environmental Research – UFZ, Department Catchment Hydrology, 06120 Halle/Saale, [email protected] Helmholtz Centre for Environmental Research – UFZ, Department of Environmental Informatics, 04318 Leipzig, Germany3 TU Dresden, Applied Environmental System Analysis, 01062 Dresden, Germany

Abstract Water is a scarce resource in the semi-arid to arid regions around the Dead Sea where the precipitation events occur mostly in winter. Average precipitation values ranges between 50 and 600 mm/year. Because of the Dead Sea Graben structure the distribution of precipitation shows a sharp drop over a short distance from the mountainous area towards the Dead Sea. But the area around the Dead Sea is also characterized by a high population density. Therefore the present study deals with the investigation of the water budget of the western

Dead Sea escarpment. A main goal is to understand the subsurface water balance of the western Dead Sea escarpment and the impact of the lowering of the Dead Sea water level. The study area is limited by the subsurface watersheds and has a size of ~4000 km2. The region is characterized by the heterogeneous aquifer system of the Judea Group. The formations of the Judea Group are separated in two sub-aquifers, the Upper Cenomanian-Turonian aquifer and the Lower Cenomanian-Albian aquifer. The objective is to quantify the surface and subsurface inflow of the western escarpment into the Dead Sea basin. This paper gives an overview of the developed regional groundwater flow model of the western Dead Sea escarpment which was achieved by the scientific software OpenGeoSys (OGS), which is specialized in coupled hydro systems processes and calculates the groundwater flow in porous and fractured media of the aquifer system (OGS 2011). The advantage of OGS is the detailed processing of the geological formations and structures (e.g. faults). Key words numerical modelling; structural model; 3D groundwater flow model; OpenGeoSys; arid region; Israel, West Bank


Propagating subsurface uncertainty to the atmosphere using fully-coupled, stochastic simulations

JOHN L. WILLIAMS, III1 & REED M. MAXWELL1,2

1 Colorado School of Mines, Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, 1500 Illinois St, Golden, Colorado 80401, [email protected] Integrated Groundwater Modeling Center, 1500 Illinois St, Golden, Colorado 80401, USA

Abstract Feedbacks between the land surface and the atmosphere, manifested as mass and energy fluxes, are strongly correlated with soil moisture under dry conditions, making soil moisture an important factor in land–atmosphere interactions. We show that uncertainty in subsurface properties propagate into atmospheric variables, and therefore reduction of uncertainty in hydraulic conductivity will propagate through land–atmosphere feedbacks to yield more accurate weather forecasts. Using ParFlow-WRF, a fully-coupled groundwater-to-atmosphere model, we demonstrate responses in land–atmosphere feedbacks and wind patterns due to subsurface heterogeneity. An idealized domain with heterogeneous subsurface properties is used in ensembles of coupled-simulations. These ensembles are generated by varying the spatial location of the subsurface properties, while honouring the global statistics and correlation structure, an approach common to the hydrologic sciences but never-before used in atmospheric simulations. We clearly show that different realizations of hydraulic conductivity produce variation in soil moisture, latent heat flux and wind for both point and domain-averaged quantities. A single random field is chosen as the “actual” case and varying amounts of hydraulic conductivity data are sampled from this realization. Using these conditional Monte Carlo simulations, we incorporate subsurface data into the ensemble of realizations. We also show that the difference between the ensemble mean prediction and the actual saturation, latent heat flux and wind speed are reduced significantly via conditioning of hydraulic conductivity. By reducing uncertainty associated with land–atmosphere feedback mechanisms, we also reduce uncertainty in both spatially distributed and synoptic wind speed magnitudes, thus improving our ability to make more accurate forecasts important for many applications such as wind energy.Key words uncertainty; land–atmosphere feedbacks; wind; heterogeneity


Multiobjective calibration of coupled soil-vegetation-atmosphere models

THOMAS WÖHLING1,2, SEBASTIAN GAYLER1, JOACHIM INGWERSEN3, THILO STRECK3, JASPER A. VRUGT4 & ECKART PRIESACK5 1 WESS – Water and Earth System Science Competence Cluster, Universität Tübingen, 72076 Tübingen, [email protected] Lincoln Environmental Research, Lincoln Ventures Ltd., Ruakura Research Centre, Hamilton 3240, New Zealand 3 Institute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, 70593 Stuttgart, Germany

4 Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, 92697 California, USA5 Institute of Soil Ecology, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany

Abstract The modular system Expert-N is adopted to analyse the effect of the complexity of soil-vegetation-atmosphere models on their calibration results. Four different models with increasing complexity are calibrated using time series of observed soil moisture, evapotranspiration, and LAI field data from a winter wheat field plot in Kraichgau, southwest Germany. The calibration of each model is posed in a multiobjective framework and three different objective functions are used to summarize the distance between measurements and simulations of different data types. The AMALGAM evolutionary search algorithm is utilized to simultaneously estimate the most important soil hydraulic and plant module parameters. Results show for most models a considerable trade-off appears in the fitting of different data types. If a mechanistic description of plant growth is considered the trade-off reduces considerably. The simplest plant model in our study performs relatively well but requires the availability of key development data of the plant. If such data are not available to the user, such models are rather useless for predictive purposes. Key words soil-vegetation-atmosphere modelling; evapotranspiration; soil moisture; leaf area index; multiobjective parameter optimization; AMALGAM; Pareto analysis; model calibration

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