CMWR2018: COMPUTATIONAL METHODS IN WATER RESOURCES XXII
PROGRAM FOR TUESDAY, JUNE 5TH
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08:30-09:25 Session 19: Keynote speaker 3
Location: Auditorium
08:30
Combining continuous and discontinuous approaches to fracture with a geometrical description of dissipation : The Thick Level Set approach

ABSTRACT. Continuous and discontinuous approaches to fracture have both their advantages and drawbacks. On one side, the discontinuous approach, Griffith type or cohesive, allows for a clear separation of matter but was not designed to take into account easily triaxiality effects close to the crack faces, as well as complicate crack patterns (merging and branching).

On the other side, continuous approaches allows one to use the full blown capabilities of bulk constitutive models but face tremendous computational cost especially when process zone sizes are important. Continuous model are also not well suited if crack opening informations need to be accessed (for instance for a coupling with fluid flow).

The Thick Level Set approach (TLS) to fracture reconciles both approaches and make them usable both at the same time. The key idea is that bulk and interfacial damage are being given a related geometrical meaning (configurational type). Both models may thus combined to create a new powerful material modeling frame.

09:30-10:30 Session 20: S11-2: Impact of groundwater in earth system science
Location: Auditorium
09:30
Global methods for a global model - applying the Morris sensitivity analysis on the global gradient-based groundwater model 3GM

ABSTRACT. To represent groundwater-surface water interactions, lateral flows as well as the human impacts on head dynamics and the impact of capillary rise on evapotranspiration it is necessary to simulate the location and temporal variation of the groundwater table. Global-scale hydrological models have recently moved to include these processes even though data is difficult to obtain. We present an application of the well-established Morris method on a newly developed Global Gradient-based Groundwater Model 3GM to assess the sensitivity of model inputs.

09:45
Assessing groundwater-stream interactions influence on ORCHIDEE land surface model dynamics: parametrization and results for Little Washita watershed

ABSTRACT. We intend to introduce a proposed global wetland map in the ORCHIDEE land surface model, acting as the riparian buffer zone which receives water both from infiltration and down-flowing runoff. This will result in increased soil moisture over the wetland fraction and sometimes building a water table in the soil column, with better representation of latent heat fluxes and seasonal variations. Results will be compared to observations and also 3-D modelling results at the Little Washita watershed in the USA.

10:00
Impact of groundwater on present-day climate and climate sensitivity in the CNRM-ESM2 Earth System Model
SPEAKER: Jeanne Colin

ABSTRACT. Groundwater being part of the surface continental hydrology, it is likely to impact the climate system. Therefore, it has recently been integrated to Earth System Models. CNRM-ESM2 includes a parameterization of unconfined aquifers in its river routing module, CTRIP, coupled to the land surface model ISBA. This hydrological system was validated in offline mode in previous studies. Here, we evaluate the effects of the simulated groundwater on present-day climate, and its impact on climate sensitivity in idealized climate change scenarios.

10:15
Impacts of groundwater on the Amazon precipitation using multi-GCM simulations from the I-GEM project

ABSTRACT. Previous studies showed when considering the groundwater dynamics in a climate model, the wet soil induced surface cooling effect can further reduce the dry season precipitation in Amazon. Further, we examine the surface cooling effects by using the idealized prescribed water table depth simulations from the I-GEM (Impact of Groundwater in Earth system Models Groundwater) project. A contradict result of the tendency of precipitation has been found, which indicates the uncertainties of the groundwater’s impacts in coupled GCMs.

09:30-10:30 Session 21: S24-2: Reactive Transport Modeling
Location: Lamennais 1
09:30
Imaging the spatial distribution of geochemical heterogeneities with inverse reactive transport modeling: The example of pyrite oxidation
SPEAKER: Massimo Rolle

ABSTRACT. In this study we propose an approach to image the spatial distribution of geochemical heterogeneities. The approach is based on distributed sensor data of water quality parameters combined with forward and inverse reactive transport modeling. The method was tested on oxidative dissolution of pyrite investigated in 1-D columns and 2-D flow-through setups.

09:45
Chemical reactions under flow heterogeneities
SPEAKER: Lazaro Perez

ABSTRACT. We examine the impact of flow heterogeneities at pore scale modeling an instantaneous bimolecular chemical reaction A + B --> C in a laminar Poiseuille flow reactor. We use a reactive random walk particle tracking method which represents the reactants by particles. We are able to predict the total amount of product C formed during the reaction through the effective dispersion coefficient, which is based on the temporal evolution of the spatial moments of the plume.

10:00
Mineral dissolution in physically heterogeneous systems

ABSTRACT. Mineral dissolution rates in physically heterogeneous systems are explored using multi-component reactive transport simulations with non-linear kinetic reactions. Results from simulations at varying spatial and temporal scales demonstrate the contribution of physical heterogeneity to the observed discrepancy between laboratory- and field- measured mineral dissolution rates. Orders of magnitude deviation from laboratory-derived dissolution rates are observed in systems where preferential pathways of fast fluid velocity bound low permeability reactive zones once reactive mineral is depleted in the preferential pathways.

10:15
A Large-Scale Model for Dissolution in Heterogeneous Porous Media
SPEAKER: Jianwei Guo

ABSTRACT. Dissolution of pore-scale soluble substances occurs in applications from environmental hydrogeology to CO2 storage. Development of Darcy-scale models has been widely discussed. This paper proposes an upscaling algorithm to develop large-scale models taking into account Darcy-scale heterogeneities. The theory is based on a comparison between the characteristic length-scale of the Darcy-scale heterogeneities and the length-scale of the dissolution front controlled by a Darcy-scale Damk\"{o}hler number. The obtained large-scale model is shown to confront favorably to Darcy-scale direct numerical simulations.

09:30-10:30 Session 22: S18-2: Multiphysics problems, coupling methods and domain decomposition in space and time
Location: Lamennais 2
09:30
A Robin-Robin domain decomposition method to couple nonisothermal compositional gas liquid Darcy and free gas flows
SPEAKER: Roland Masson

ABSTRACT. A domain decomposition algorithm is introduced to model the mass and energy exchanges between the geological formation and the ventilation galleries of a geological radioactive waste disposal. At each time step, the algorithm solves iteratively the nonisothermal gas liquid Darcy flow in the porous medium, the RANS gas flow in the free-flow domain, and the transport and energy equations in the free-flow domain. To speed up the convergence, Robin type boundary conditions with optimized coefficients are designed.

09:45
Using a posteriori error estimates to stop the iterations in a space-time domain decomposition method for porous media flow

ABSTRACT. We present a space-time domain decomposition method for the simulation of subsurface flow, based on based on the Optimized Schwarz Waveform Relaxation algorithm, which enables local time stepping.

In order to decide when to stop the DD iterations, we have developed fully computable a posteriori error estimates that allow for the separation of the part of the error due to the space and time discretizations, and that due to the DD iterations. These error estimates are based on reconstruction techniques.

10:00
A Fully Implicit Finite Volume Scheme For Flows With Reactive Transport In Porous Media

ABSTRACT. We develop a fully implicit finite volume scheme for numerical modeling of single and two-phase multicomponent flow with reactive transport in porous media. Modeling such problems leads to a highly nonlinear coupled system of PDEs to differential algebraic equations or ODEs. We have developed and integrated reactive transport modules in the DuMuX framework. Numerical results for 1D and 2D including benchmarks tests will be presented. The results have demonstrated that this approach yields physically realistic flow fields in heterogeneous media.

10:15
[RESCHEDULED FROM MONDAY Session 07: S02-1] Efficient Iterative Solution and Multiscale Approximation of Anisotropic and Heterogeneous Problems with Applications

ABSTRACT. While finite element analysis is a well-established tool in science and engineering, traditional solver approaches become inefficient or even break down entirely for strongly heterogeneous problems and anisotropies. The topic of this talk is the GenEO spectral coarse space which can be used to either construct preconditioners that perform well in these situations or to generate efficient coarse representations in multiscale applications. A highly scalable implementation in the DUNE numerical framework will be presented alongside numerical results demonstrating its effectiveness.

09:30-10:30 Session 23: S09-1: Fractured rock hydromechanics and seismicity
Location: Lamennais 3
09:30
(Featured speaker) Induced seismicity and In situ mapping of pore pressure

ABSTRACT. In fractured rock masses, fluid flows through interconnected channels. These channels are separated by solid bridges that transmit shear stresses. When the local fluid pressure gets large enough, it generates seismogenic slips. A combined inversion of direct stress measurements and focal mechanisms of induced seismicity helps map the pore pressure magnitude. Results from an in situ experiment help demonstrate the existence of poorly connected channels. They have been confronted to in situ testing that demonstrated the role of hydromechanical coupling

09:45
(Featured speaker) Insights into complex sub-decimeter fracturing processes occurring during a water-injection experiment at depth in Äspö Hard Rock Laboratory, Sweden

ABSTRACT. We investigate the source characteristics of picoseismicity recorded during a hydraulic fracturing in-situ experiment performed in Äspö Hard Rock Laboratory, Sweden. Six stimulations resulted in induced seismicity with MW<-3.5 (sub-dm size fractures). The results of monitoring and analysis are discussed in the context of seismic injection efficiency and maximum potential magnitude

10:00
Aseismic motions drive a sparse seismicity during fluid injections into a fractured zone in a carbonate reservoir

ABSTRACT. We developed an in-situ experiment of fluid injections at a 10-meter scale. Water was injected at high-pressure in a fault, in limestone at 280 m depth in the LSBB Underground Laboratory (France). Induced seismicity, as well as strains, pressure and flowrate were continuously monitored during the injections. Although plastic deformations related to fracture reactivations were observed for all injections, only a few tests generated seismicity. Comparing strain measurements and seismicity shows that more than 96% of the deformation is aseismic.

10:15
Exploring in situ fracture hydromechanics from high resolution surface tilt and borehole strain observations

ABSTRACT. Estimating the hydro-mechanical properties of fractured rock reservoirs is critical for many engineering practices. Laboratory and numerical experiments have brought considerable insights, but in situ hydromechanical experiments are relatively uncommon. We propose a new experimental design based on the combination surface tilt and borehole strain observations in sinusoidal hydraulic tests to access both local fracture behavior and its connectivity to the fractured network at ~10m scales.

09:30-10:30 Session 24: S15-1: Microorganisms in heterogeneous flows: integrating from the cellular to the system-scale and from fundamental physics to applications
Location: Lamennais 4
09:30
Micro-scale heterogeneous bacterial distribution impacts on biodegradation

ABSTRACT. The microorganisms in groundwater rarely cover the matrix uniformly, but form colonies. This limits substrate bioavailability and biodegradation. With a high-resolution numerical model of a pore channel with bacterial colonies we simulated the transport and biodegradation of organic substrates and compared them to 1D simulations based on effective rate laws for bioavailability-limited biodegradation. We quantified bioavailability limitations and evaluated the applicability of established effective rate concepts if microorganisms are heterogeneously distributed. Effective bioavailability was reduced (> one order of magnitude).

09:45
Interaction of porosity structures and microbial uptake dynamics in the degradation of pesticides at µm and mm scales

ABSTRACT. Pesticide leakage through soil results in critical challenges of health and environment. Yet, the mechanisms of pesticide biodegradation in soils are not fully understood. This work aims to formalize the couplings between spatial processes resulting from the saturation structure, sorption processes and microbial processes involved in biodegradation. Through two reactive transport models, we show that these couplings lead to non-linear uptake and biodegradation of pesticide by microorganisms. Strong discrepancies between initial conditions and biodegradation response can emerge from this non-linearity.

10:00
Filtration of biocolloids by porous media: the role of flow disorder
SPEAKER: Filippo Miele

ABSTRACT. A microfluidic model will be introduced to quantify the impact of flow field heterogeneity in filtration of microbial particles (bio-colloids). Long tailing behavior and non-exponential deposition profile are observed in experimental data but not predicted in classical filtration theory (CFT). We use 2D particle tracking simulations and microfluidics experiment to investigate bio-colloids transport and filtration and we upscale the observed macroscopic filtration process in the framework of Reactive Continuous Time Random Walk (R-CTRW) model.

10:15
High-resolution Simulation of Denitrification
SPEAKER: Olaf Ippisch

ABSTRACT. Denitrification by bacteria is modelled as a reaction-diffusion process, consisting of coupled reaction-diffusion equations, in a high-resolution pore space geometry obtained form X-ray micro-tomography. The model results are compared to experimental data obtained in laboratory experiments with an ensemble of artificial aggregates form sintered glass, inoculated with bacteria from two different strains capable of denitrification.

10:30-11:00Coffee Break
11:00-12:15 Session 25: S12-1: Integrated Hydrologic Models: Coupled Surface and Subsurface Flow
Location: Auditorium
11:00
Integrated Water Resource Modeling with Carbon Storage and Plant Growth
SPEAKER: Jason Davison

ABSTRACT. To improve the current generation of land surface models, we coupled HydroGeoSphere (HGS), a 3D fully integrated surface and variably saturated subsurface flow and transport model to the Noah-MP (Multi-Physics) LSM. The coupling method starts with Noah-MP processing the external climate forcing data (e.g. solar radiation, precipitation, wind velocity, and humidity) and provides HGS node specific net precipitation data. Conversely, the 3D HGS model replaces the internal water balance within Noah-MP by providing it soil saturation.

11:15
[CANCELLED] A model intercomparison of a land surface model and a coupled surface subsurface model with a focus on the scaling behaviour

ABSTRACT. We analyse the similarities and the differences of the conceptual land surface model mHM and the physically based coupled surface subsurface model TerrSysMP. A special focus lies on the scaling behaviour of the spatial and the temporal resolutions.

Therefore, we simulate the Rur and the Bode catchments with both models with resolutions ranging from 200m x 200m to 1km x 1km per cell and from daily to annual timesteps.

11:30
Solutions to Improve Stream-Aquifer Model Parameter Estimation and Uncertainty Analysis

ABSTRACT. We present two ways to overcome the computational burden associated with GW-SW models, which is a barrier to the use of parameter estimation and uncertainty analysis: i) An tool to compute the head-dependant stream boundary condition, which is a solution to obtain frugal GW-SW models; ii) a surrogate GW-SW transport model based on particle tracking, with short computation time. These approaches increase the robustness of SW-GW models prediction and make possible the use of advanced techniques to optimize decision variables

11:45
Including riverbank seepage and riverbed heterogeneity in modeling river-aquifer interaction in MODFLOW: a new approach
SPEAKER: Gert Ghysels

ABSTRACT. A new approach for modeling river-aquifer exchange fluxes is proposed which provides the tools to incorporate riverbed heterogeneity and anisotropy. Furthermore, it incorporates the contribution of lateral fluxes through the riverbanks. The method has been successfully applied on an artificial V-catchment model, and on a real case study of an existing gaining lowland river, the Aa River. This method can be used to improve the understanding of riverbed heterogeneity and bank seepage, and their effect on river-aquifer exchange fluxes.

12:00
An ensemble approach for coupling conceptual rainfall runoff model with physically based groundwater model

ABSTRACT. An ensemble approach to couple different conceptual hydrological models with a physically based groundwater component in a modelling framework has been developed. It allows to employ the conceptual output of the rainfall runoff model as an input for transient groundwater modelling. The approach also helps to reduce the overparameterization by using the lumped conceptual recharge models with less calibrated model parameters. Furthermore, it enables the possibility to quantify the uncertainty on groundwater model results given by different recharge models.

11:00-12:15 Session 26: S24-3: Reactive Transport Modeling
Location: Lamennais 1
11:00
Alquimia: an application programming interface for geochemical codes- Development and application
SPEAKER: Sergi Molins

ABSTRACT. For convenience implementation of new geochemical capabilities into flow and transport codes is often circumvented by coupling them to existing reaction codes. Here we introduce Alquimia, an API and wrapper library that provides a unified interface to the biogeochemistry routines from existing codes. We demonstrate the development with the implementation of interfaces to the geochemical capabilities of PFLOTRAN and CrunchFlow. Next, we demonstrate its use in the addition of geochemical capabilities to a newly develop flow and transport simulator, Amanzi.

11:15
MIN3P-THCm-USG: a fully unstructured grid code for subsurface flow and reactive transport simulation
SPEAKER: Danyang Su

ABSTRACT. This presentation introduces the approach used to implement fully unstructured grid discretization into MIN3P-THCm, a process-based numerical model designed for the investigation of subsurface fluid flow and multicomponent reactive transport in variably saturated media. The unstructured grid code, MIN3P-THCm-USG, uses a hybrid vertex-cell-centered control volume method, with options for different control volume discretization approaches, gradient reconstruction methods and cell types. The code’s capability for simulations involving complex geometry has been demonstrated through a series of verification examples.

11:30
How Do We Couple Pore- to Darcy-scale Flow and Reactive Transport in A General Way?
SPEAKER: Xiaofan Yang

ABSTRACT. This research aims to extend and apply a recently-developed multiscale universal interface (MUI) to dynamically couple pore-scale and Darcy-scale models (both solved using the lattice Boltzamann method, LBM) to study flow and reactive transport in porous media. The current work will address both scientific questions and multiscale methodology challenges: 1) How does the heterogeneity affect mixing-controlled reactive transport in porous media? and 2) How to best generalize hybrid multiscale methodologies in a high-performance computing environment?

11:45
Pore-scale reactive transport modeling of mineral-water interactions and implications for reaction rate upscaling
SPEAKER: Hang Deng

ABSTRACT. Pore-scale heterogeneity in pore geometry and mineral spatial distribution largely control the interactions between minerals and fluids. In order to investigate how pore-scale processes affect the bulk properties of a representative elementary volume (REV), a pore-scale reactive transport model was developed and used to simulate geochemical reactions, flow and transport in heterogeneous pore structures. The simulation results are used to develop a framework for upscaling of rock properties - reaction rate in particular.

12:00
Discontinuous kinetics models for reactive transport problems

ABSTRACT. We propose a discontinuous modeling of chemical kinetics for general multiphase problems. This discontinuous modeling is regularized in order to solve a PDE with a continuous right-hand side. We then apply our work to academic and industrial cases.

11:00-12:15 Session 27: S18-3: Multiphysics problems, coupling methods and domain decomposition in space and time
Location: Lamennais 2
11:00
Coupling concepts for free-flow and porous media systems
SPEAKER: Rainer Helmig

ABSTRACT. Soil-moisture processes in the subsurface play a crucial role in the hydrological cycle and the groundwater budget. We will present a conceptual model for coupled single-phase free flow and two-phase porous-medium flow with a detailed description of the models in the free flow and in the porous medium and provide a new coupling concept for modelling coupled porous-medium and free flow.

11:30
Thermo-Chemo-Hydro-Geomechanical Model and Numerical Solution Strategy for Marine Gas Hydrate Geosystems with a focus on Gas Production and related Geohazards

ABSTRACT. Gas hydrate reservoirs, in the context of a future energy resource, are complex subsurface geo-systems characterized by large material heterogeneities, local anisotropies, and a large number of strongly coupled multi-physics processes, including: 1) hydrate phase change; 2) multi-phase, multi-component flows; 3) thermal effects; 4) geomechanical deformation and plastic failure; and 5) sand migration. In this talk, we present our mathematical model, decoupling strategy, and numerical solution scheme for gas-hydrate geosystems with a focus on gas production and geotechnical risks quantification.

11:45
Efficient DG-based simulation of coupled surface subsurface flow

ABSTRACT. An approach for coupled surface surface flow is presented, which is based on a diffusive wave approximation for surface and Richards' equation for subsurface flow. An operator splitting approach based on Discontinuous Galerkin discretizations is used with a coupling via appropriate boundary conditions. The numerical solver is implemented using techniques from the EXA-DUNE project to obtain a high computational efficiency.

12:00
Poromechanics based on Minimization -- Models and Solvers
SPEAKER: Jakub Both

ABSTRACT. Classically models coupling mechanical deformation and fluid flow in porous media are stated as PDEs. Recently, for fully saturated porous media, a minimization formulation of Biot's equations has been introduced yielding an alternative to the standard approach. In this work, (1) we discuss the applicability of minimization principles as modeling tool for nonlinear poromechanics, and (2) we exploit the minimization formulation and apply optimization methods in order to solve the coupled problem efficiently in a decoupled fashion.

11:00-12:15 Session 28: S09-2: Fractured rock hydromechanics and seismicity
Location: Lamennais 3
11:00
(Featured speaker) Fault slip reactivation by fluid injections : aseismic slip and induced seismicity in rate-and-state fault models

ABSTRACT. Fluid operations at depth trigger a significant amount of seismicity and aseismic deformation, which could be interpreted as the reactivation of rapid or slow slip on preexisting fracture. Here we present results about the dynamics of slip reactivation on a planar Dieterich-Ruina rate-and-state fault model permeated by a fluid. We show how such models allow to better identify the mechanical parameters controlling the amount and the size of induced earthquakes, and the magnitude of aseismic response.

11:15
Expected influence of overpressure on observed induced seismicity sequences

ABSTRACT. Monte Carlo simulations with a hybrid model of Enhanced Geothermal Systems (EGS) return quickly physics based answers to the question: ``Does continuing the stimulation, worth the additional induced seismicity risk?`` Here, a hybrid model is presented that employs accurate 3D numerical modeling for flow, heat transport, stochastic modeling for seismicity, allowing numerical experiments that study the effect of overpressure on induced seismicity. The proposed tool provides useful insight on long term forecasts of induced seismicity and thermal revenue.

11:30
The nucleation of injection-induced earthquakes: The role of poroelasticity

ABSTRACT. Recent observations have shown that changes in pore pressure due to the injection of fluids from underground formations may induce earthquakes. We have developed a numerical framework with fault frictional contact described by the Dieterich–Ruina rate-and-state friction law and we model rock as a poroelastic solid. We investigate the nucleation phase earthquakes. This phase is essential, since nucleation patterns may provide the key to detect preseismic signals and estimate the magnitude of the earthquake.

11:45
Fault activation induced by human activities: uncertainty quantification and parameter update

ABSTRACT. Activation of faults due to human-induced operations is becoming extremely important for risk assessment analysis and reservoir management. The variation of the loading conditions due to injection and/or extraction of fluids may cause the faults re-activation and the opening of new fractures that may generate (micro)seismic events. The aim of this work is at developing a Bayesian framework to quantify and possibly reduce the uncertainties linked to such human activities.

12:00
Three-dimensional numerical modelling of hydraulic stimulation of geothermal reservoirs: permeability enhancement and induced seismicity
SPEAKER: Inga Berre

ABSTRACT. Hydraulic stimulation to reactivate and shear-dilate fractures can successfully enhance the permeability of geothermal reservoirs sufficiently to obtain commercial flow rates. The process involves highly coupled hydromechanical processess. We present a hybrid approach for modelling where fractures are modelled as surfaces with associated apertures in a three-dimensional domain.

Results show how the methodology can be applied to understand important mechanisms affecting permeability enhancement as well as induced seismicity. We also discuss its potential in combination with field observation data.

11:00-12:15 Session 29: S15-2: Microorganisms in heterogeneous flows: integrating from the cellular to the system-scale and from fundamental physics to applications
Location: Lamennais 4
11:00
Chemotaxis and flow disorder shape microbial dispersion in porous media

ABSTRACT. We introduce a microfluidic model to image and quantify the role of cell motility on bacterial dispersion and residence time. Using the bacterium Bacillus subtilis, we observe that chemotaxis in highly disordered and confined physico-chemical environment affords bacteria an increase in their ability to persistently occupy the host medium. Our findings illustrate the interplay between bacterial behavior and pore-scale disorder in fluid velocity that impacts the residence time and transport of biota in the subsurface.

11:15
Microbial horizontal gene transfer in flows

ABSTRACT. The soil-bacteria interaction is fundamental for many terrestrial ecosystems processes. Some of these bacteria have the ability to uptake and express exogenous free DNA, a mechanism of gene transfer known as natural transformation. We used microfluidics devices combined with fluorescent optical micoscopy to observe the effect of different flow conditions on this mechanism. Preliminary experiments ran with engineered bacteria show that this method is very promising to study this process source of biodiversity with bacteria species from the environment.

11:30
Fractures sustain dynamic microbial hotspots in the subsurface

ABSTRACT. We present field observations providing new insights on the role of fractures in the formation of a hot spot of microbial activity. We have analyzed the conditions for the formation of a microbial mat composed of iron-oxidizing bacteria at 60 meters depth in the Ploemeur fractured rock observatory. These results show that heterogeneous flowpaths, linked to the structure of fractured media, create mixing zones between iron rich water and oxygen rich water, at the origin of the microbial hot spot.

11:45
Hybrid cellular automata / PDE modeling for solid restructuring including EPS

ABSTRACT. We assess the complex coupling of biological, chemical and physical processes at different scales with the help of a mechanistic modelling approach. It combines a discrete cellular automata/PDE model on the microscale to account for restructuring of soil microaggregates under the influence of geochemistry, transport and attractive forces by charges or glueing agents as EPS stemming from microorganisms. Effective parameters of interest can then be upscaled to the macroscale. Simulations complement aggregation experiments for goethite and illite with EPS.

12:00
Analysis of the influence of growth conditions on the competition between biological aggregate morphotypes: biofilms, flocs and streamers
SPEAKER: Yoan Pechaud

ABSTRACT. In this study, we focus in analyzing the influence of operating conditions on the competition between 3 aggregate morphotypes in biofilm reactors: biofilms, flocs and streamers. The main objectives are: (i) to improve understanding of the mechanisms controlling the competition between the three microbial morphotypes and (ii) to analyze the dynamics of streamers formation.

12:15-14:00Lunch Break
14:00-14:55 Session 30: Keynote speaker 4
Location: Auditorium
14:00
Groundwater-to-atmosphere simulations under human water use conditions over the European continent

ABSTRACT. Groundwater-to-atmosphere simulations are useful for closing the terrestrial water and cycle at the continental scale and interrogating anthropogenic impacts at different space and time scales. We want to understand how human water use, in this case groundwater pumping and irrigation, changes the natural terrestrial cycles over the European continent including local effects, such as changes in water table depths, evapotranspiration, and air temperature, and non-local effects, such as base flow, continental discharge and precipitation. In particular, we study whether these changes are systematic in space and time, and ultimately impact and potentially redistribute water resources across the continent. We present technical aspects of our work related to model coupling and high-performance computing technologies, and results illustrating the significant impact of human water use beyond individual watersheds.

15:00-16:30 Session 31: S12-2: Integrated Hydrologic Models: Coupled Surface and Subsurface Flow
Location: Auditorium
15:00
Integrated groundwater-surface water hydrologic modeling at the continental scale and its applications

ABSTRACT. Groundwater storage and evapotranspiration, which are important components of the water cycle and critical to national, regional and local resource management at ranging scales, are both notoriously difficult to observe. Here we present the results of an integrated, physically-based hydrologic model that spans the entire contiguous United States (CONUS) at hyper-resolution. We discuss a modern-day scenario diagnosing groundwater controls on surface fluxes and energy, and demonstrate applications of large scale physically based modeling to bridge observation and decision-making scale gaps.

15:15
A New Approach to Predicting the Effect of Climate Extremes on California’s Water Supply

ABSTRACT. Standard water management practices neglect the complex dynamics between surface and subsurface waters, making the prediction of groundwater storage in water-limited areas such as the western US highly uncertain. Although a large-scale terrestrial water balance is possible via remote sensing techniques such as GRACE, it lacks the ability to separate groundwater from surface water. This work aims to isolate groundwater from such datasets utilizing a high-resolution integrated hydrologic model by explicitly simulating individual components of a representative Sierra Nevada watershed.

15:30
The AquiFR hydrogeological modeling platform: evaluation of the 1958-2017 reanalysis for the main regional multilayer aquifers in France.

ABSTRACT. The French AquiFR modeling platform gathers hydrogeological models coupled with the SURFEX land surface model. The objective is to provide forecasts of the groundwater resources for operational and climate applications. We present here the evaluation of the 1958-2017 hydrogeological reanalysis for multiple regional multilayer aquifers. The evaluation is made against selected observations in order to identify the potential to capture extreme events in long-term simulations. This reanalysis will allow to dispose of a referential state needed for operational applications

15:45
An integrated hydrologic model approach to evaluate the compounding impacts of groundwater extraction and severe drought on groundwater and surface water supplies in the California Central Valley
SPEAKER: Lauren Thatch

ABSTRACT. Between 2013 and 2015 California, and the already water stressed Central Valley, experienced the worst drought in its recorded history. We used the fully integrated hydrologic model, Parflow, coupled with CLM to evaluate the combined impacts of drought and groundwater extraction using multiple groundwater extraction and management scenarios. Model results were evaluated using a combination of observations and GRACE groundwater storage estimates. With this approach, we provide a method to inform sustainable groundwater use and management during severe climatic conditions.

16:00
A groundwater model as a benchmark for a fully-integrated supra-regional-scale hydrological modeling

ABSTRACT. Integrated hydrological modelling has become more and more important to bring sufficient insight in a climate change effects investigation on hydrological cycle. Nevertheless, a quantitative evaluation of the uncertainty is a challenging issue due to the long run times. As a first step, we propose to consider a pure groundwater model to identified optimal parameter estimation strategies. This will serve to save computation time and bring accessible the uncertainty analysis on the later integrated hydrological model.

16:15
Simulating the Effects of Changes in Climate and Land Use on Streamflow and Groundwater Storage in the Midwestern United States
SPEAKER: David Hyndman

ABSTRACT. Humans are having dramatic effects on the water cycle with irrigated agricultural practices. Using a process-based integrated hydrologic model, we simulate the effects of historical changes in climate and land use on streamflows and groundwater storage along with scenarios of projected climate change. We also simulate feedbacks of irrigation on climate in a WRF regional climate model, which shows that irrigation across the continental United States have significant effects on precipitation and temperatures in the eastern US.

15:00-16:30 Session 32: S10: Multiscale Data-Model Integration for Simulation of Complex Flow and Reactive Transport Systems
Location: Lamennais 1
15:00
Hybrid multiscale modeling to couple pore and continuum scale processes of transport, reaction and biofilm growth along a transverse mixing zone

ABSTRACT. We develop a hybrid multiscale method for mixing-controlled reactions and biofilm growth. Non-overlapping regions at pore and continuum spatial scales are coupled by a suitable method that ensures continuity of flux across the interface. Thus, regions of high reactivity where flow alteration occurs are resolved at the pore scale for accuracy while regions of low reactivity are resolved at the continuum scale for efficiency. We present results for simplified two-dimensional scenarios with transverse mixing of electron donors and acceptors.

15:15
Hybrid multi-scale modeling of reactive transport in fractures– An adaptive embedded-boundary approach
SPEAKER: Sergi Molins

ABSTRACT. Understanding fracture evolution is essential in many subsurface applications. Conceptually, fractured systems have been represented as being composed of fast flow paths -the fractures- and slow flow paths - the rock matrix. While reactive transport in the fractures can be better simulated with a pore scale model, a Darcy-scale continuum model may be sufficient for the matrix. Here we extend a previously developed pore-scale model based on an adaptive embedded-boundary approach to add a Darcy-scale representation of reactive porous media.

15:30
Efficient Multiscale Modeling of Fracture Networks Using Graph-based Representations

ABSTRACT. Flow through fractured media in the sub-surface is heavily dependent on microstructural information. Continuum models often eliminate features critical to accurately predicting macroscale behavior but are commonly used since resolving thousands of fractures individually is computationally intractable. We overcome this hurdle by developing compact graph representations of the fracture networks, and using machine learning algorithms to mimic the detailed physics at the microscale. The resulting workflow has been shown to achieve upto 4x computational speedup while maintaining accuracy.

15:45
Coupled Solid-Fluid Dynamics in Heterogenous Porous Media

ABSTRACT. We developed a method through which we can model coupled fluid-porous media dynamics such as clay swelling and fluid-induced clay transport within Digital Rock Physics. Fluid flow in these scenarios is modeled through the Darcy-Brinkman Equation, which approximates Navier-Stokes in a free fluid, and Darcy’s Law in a microporous (clay) domain. Coupling with geomechanics is achieved by incorporating porous media conservation equations (with appropriate momentum sources) into this framework. This model’s application can go beyond clay and cap rock modeling.

16:00
[CANCELLED] Pore Scale Simulation of Immiscible Two-Phase Flow at Low Capillary numbers

ABSTRACT. Accurate modeling of Moving Contact Line (MCLs) at low Capillary numbers requires honoring the interfacial jump conditions and capturing the multiscale physics. We use a level-set coupled with Navier-Stokes equations (LSNS). The LSNS model captures MCLs in the presence of a thin film that covers the solid surface. We use a low-dimensional film model with disjoining pressure. Several validation cases are presented. We also discuss the effect of roughness on film stability at low Capillary numbers.

15:00-16:30 Session 33: S22: Observatories, remote sensing, data-driven modeling
Location: Lamennais 2
15:00
Use of High Frequency measurements to better determine the concentration-flow relationship (C-Q) of the Avenelles watershed (ORACLE Obs.)

ABSTRACT. The present work is based on the study of concentration-flow relationship from high frequency measurements, made in ORACLE Observatory (Paris, France) using a mixture equation, which is based on the separation of the hydrographs (runoff, subs-surface and groundwater). Thanks to the high frequency (measurements made every 30 minutes) the C-Q ratio is much more accurate than those made from point measurements (e.g., each week or month), allowing us to better understand the hydrogeochemical processes of the catchment.

15:15
Interest and complementarity of physical and chemical monitoring to model the critical zone

ABSTRACT. Critical zone is a complex system where water cycle occurs. Understanding at several scales hydro(geo)logical processes will allow a sustainable water management. Here, we assess the informative content of pluridisciplinary measured data on the Ploemeur observatory (France). From several years of measured hydraulic heads, deformations, concentrations and discharges, we refine our understanding. First we model piezometry, then, other components have been added. Finally, bringing back parameters set exploration to the theoretical framework permits to extract information about processes.

15:30
Groundwater discharge into a coastal freshwater pond impacts an aquatic ecosystem
SPEAKER: Eliot Chatton

ABSTRACT. Quantifying water and element fluxes, mixing of different water bodies and the impact of ecological processes is essential to understand the ecosystem dynamics and resilience. Here, we show how high spatial resolution of dissolved gas data can decipher the spatial heterogeneity of water sources and biogeochemical processes. These innovative experiments implemented on a classified coastal wetland downstream a hydrogeological observatory (H+ Ploemeur) allowed to localise and quantify groundwater discharges and biogeochemical reactivity hotspots associated with a deep concentration of cyanobacteria.

15:45
Constructing an everywhere and locally relevant predictive model of the West-African critical zone

ABSTRACT. The West-African critical zone is undergoing strong climatic (e.g. the observed intensification of extreme precipitation) and anthropogenic changes (e.g. +3% of demographic rate, inducing rapid land use changes) which already affect coupled hydrological systems as surface water/groundwater. Managing large hydrosystems call for integrated models to analyze present changes and anticipate future ones. We construct a high resolution (1 km²) regional scale physically-based model using ParFlow-CLM that is evaluated using AMMA-CATCH observation database which covers 3 supersites with contrasted environments.

16:00
Ecohydrological response of a continuous vegetation transect in wetlands during a typical flooding process

ABSTRACT. In seasonal flooding wetlands,the strong coupling between vegetation and biological, hydrological, meteorological & physicochemical elements leads to important feedbacks between ecosystem processes and environmental changes.In this research, a typical flooding process was captured in one typical freshwater wetlands in China. The ecohydrological response of a continuous vegetation transect in wetlands was investigated during a typical flooding process in 2017. Simulated Results show distinct difference among plant types and are concordant with the in-situ monitoring data in the transect.

16:15
Digital Watershed: Advanced Watershed Characterization across Scales

ABSTRACT. We develop novel watershed-characterization methodology to quantify complex watershed systems across scales, using advanced sensing, inversion, and machine learning approaches. We integrate multi-scale multitype datasets of surface geophysics (e.g. electrical, seismic), airborne electromagnetic survey, airborne LiDAR and satellite/UAV images. By characterizing heterogeneous properties over the watershed, we aim to develop the new ‘Digital Watershed’ concept for model parameterization and validation of hydrological and biogeochemical simulations.

15:00-16:30 Session 34: S04: Characterizing and modeling solid-solution reactivity: from atoms to pore networks
Location: Lamennais 3
15:00
A multi-scale approach to study mineral dissolution: Kinetic Monte Carlo models and experimental observations

ABSTRACT. Mineral dissolution and growth rate variability is one of the most important unresolved problems in modern geochemistry. We approach this problem by using Kinetic Monte Carlo (KMC) techniques as a hypothesis testing tool. We developed KMC models that allow to vary the crystal surface reactivity at will. Comparison of KMC results with experimental data provide insight into reaction mechanisms of phyllosilicates, quartz and calcite dissolution and identify sources of rate variability.

15:15
3D Modeling from X-ray computed tomography images : Crystals properties in Magma

ABSTRACT. Experimental samples of basaltic composition were created in laboratory conditions at various temperatures. This allowed in-situ observations of crystals using X-ray tomography beam lines at Spring-8. Analyses of crystals properties in the synthetic magma were rendered possible through automatic processing using software for CT treatment. Crystals were modeled in 3D using the numerical platform 3DEXPERIENCE© developed by Dassault Systèmes (DS). The 3D imaging facilitated the study of crystals shapes, texture and interaction between mineral species and magma.

15:30
Short- and long-range interactions at solid-water interfaces

ABSTRACT. A common theme in fundamental examinations of adsorption, wetting, nanoparticle aggregation, and nanofluidics is the difficulty of accounting for both short- and long-range interactions. In particular, computational models largely rely on mean-field theories that neglect short-range interactions and treat the fluid as a viscous dielectric continuum. Here, we discuss how molecular dynamics simulations of mineral-water interfaces, mineral-water-CO2 wetting, and nanoparticle interaction in liquid water can provide insight into the relative importance of short- and long-range interactions at mineral-water interfaces.

15:45
Dynamics of celestine precipitation and dissolution in confined spaces: a lab-on-a-chip experiment and complementary pore scale modelling.

ABSTRACT. A microfluidic cell was designed to investigate kinetically controlled dissolution/precipitation reactions in confined spaces. Strontium chloride solution and sodium sulphate solutions were allowed to diffuse across of the cell resulting in the precipitation of celestine. The growth of the celestine crystals were monitored by optical microscopy. Pore scale modelling based on Lattice Boltzmann method was used to estimate concentrations and fluid velocities at the fluid-solid growing interface and to gain an insight of the underlying observed processes.

16:00
Shales and geological waste repositories: from microstructure description to macro-scale properties

ABSTRACT. In this presentation we will highlight the complex interplays of mineralogical, chemical and microstructural characteristics of clay materials that are ultimately responsible for a remarkable array of macro-scale properties such as specific adsorption, high swelling pressure, semi-permeable membrane properties, and non-Fickian diffusional behavior.

16:15
Dynamics of altered surface layer formation on dissolving silicates: the example of wollastonite
SPEAKER: Damien Daval

ABSTRACT. Upscaling mineral dissolution kinetics experiments to geological timescales is complicated by the observation that mineral dissolution rates decrease with time. Here, we related time-resolved wollastonite dissolution rate to the physicochemical evolution of the amorphous silica-rich layers which developed on each surface. Some faces were quickly passivated, because of progressive densification of the surface layer, which limits the transport of reactive species at the fluid-mineral interface. Accounting for these gradual changes appears essential to better reproduce temporal decline ofmineral weathering rate.

15:00-16:30 Session 35: S23-1: Parameter Estimation and Uncertainty Quantification in Water Resources Modeling
Location: Lamennais 4
15:00
(Featured speaker) Multiple-point statistics simulation and inversion using a spatial generative adversarial neural network
SPEAKER: Eric Laloy

ABSTRACT. Probabilistic inversion within a multiple-point statistics framework can be intractable for high-dimensional problems. We therefore introduce a new training-image based simulation and inversion approach for complex geologic media. It relies on a deep, spatial generative adversarial network (SGAN) which defines a (very) low-dimensional parameterization. This allows for efficient probabilistic (or deterministic) inversion using state-of-the-art Markov chain Monte Carlo (MCMC) methods. Synthetic case studies involving 2D steady-state flow and 3D transient hydraulic tomography are used to demonstrate our proposed SGAN-based inversion.

15:15
Predicting remediation efficiency of polluted aquifers by comprehensive data assimilation and forward modelling
SPEAKER: Ziv Moreno

ABSTRACT. Remediation predication under uncertainty for a case study of a contaminated site in Israel is considered. A Monte Carlo approach is adopted and various indicator realizations of the aquifer structure were generated. Uncertainty regarding the plume distribution prior to remediation was evaluated using a forward predictive approach, i.e. reconstructing the plume shape and hydraulic head measurements. Remediation simulations showed that generating a reliable initial plume reduced the uncertainty in estimating remediation efficiency by more than 35%.

15:30
Estimation and Impact Assessment of Input and Parameter Uncertainty in Predicting Groundwater Flow with a Fully Distributed Model

ABSTRACT. We present a general and flexible Bayesian approach using uncertainty multipliers to simultaneously analyse the input and parameter uncertainty of a fully distributed groundwater flow model with consideration of the heteroscedasticity of the groundwater level error. New heteroscedastic error model for groundwater level included to consider the heteroscedasticity. The results confirm that input uncertainty is the dominant source of uncertainty in the groundwater flow prediction and use of groundwater recharge and abstraction multipliers leads to physically more realistic results.

15:45
Bayesian inversion for discrete parameter fields

ABSTRACT. The posterior population expansion (PoPEx) is a new technique that was developed to invert discrete parameter fields using a given prior distribution. The main characteristics of this approach is that it allows dealing with categorical variables. Solving an inverse problem in such discrete cases usually is very difficult time consuming. The main advantage of PoPEx is that it is more effective than existing Markov Chain Monte-Carlo approaches while it estimates accurately the level of uncertainty.

16:00
Using sensitivity analysis to determine effective hydraulic conductivity and mannings n parameters at multiple modeling resolutions in a mountain headwater catchment.
SPEAKER: Lauren Foster

ABSTRACT. Integrated models are increasingly run at catchment or larger scales as the demand for regional models increases. Computational resources for these complex models limits traditional parameter calibrations. Here we present a suite of sensitivity analyses in a 255km2 mountainous domain that varies hydraulic conductivity and mannings n over orders of magnitude at 1km and 100m resolution. We develop a methodology to downscale/upscale K and n in complex domains by incorporating slope into effective K and n parameters.

16:15
Adjusting the complexity level of groundwater models

ABSTRACT. A question that should be addressed at the early stage of model development: What is the optimum level of complexity for the purpose of the study? The complexity cursor should be adjusted for the model to be sufficiently faithful to the processes governing the predictions of interest, but sufficiently simple for model analysis methods to remain practical. The approach will be illustrated with practical case-studies. These examples highlight the benefits of choosing the relevant level of model complexity.

16:30-18:30 Session 36: Posters session
Location: salle du Grand Large
16:30
Poster 1. USING REACTIVE TRANSPORT MODEL TO SIMULATE AN HYDROTHERMAL SYSTEM IN THE POCURO FAULT ZONE (CENTRAL CHILE)

ABSTRACT. In the Aconcagua upper basin some thermal springs outflow spatially related to the Pocuro Fault. The outcrops related to this fault show the presence of several hydrothermal minerals filling fractures suggesting a hotter fluid circulation in the past. To better understand the groundwater circulation and fluid evolution in this system we have used Reactive Transport Models. Three different scenarios have been run by means of Crunchflow software the mineralogical, hydrogeological and geochemical set was implemented to reproduce the field observations.

16:30
Poster 2. A regional-scale hillslope aggregating watershed model: application over Brittany

ABSTRACT. We propose a new and efficient approach to model and calibrate shallow groundwater flow at regional scale and its contribution to water cycle. The hillslope is set as the basic element, where flow is resolved in 1D under the Boussinesq approximation. The model is validated on baseflow analytical solutions. We also show that baseflow analysis offer the opportunity to represent heterogeneity and calibrate the model at basin scale with river discharge data.

16:30
Poster 3. Groundwater resource in northern France from XXth to XXIth centuries

ABSTRACT. Studying both past and future long term evolutions of the groundwater resource helps pointing out how extreme could be the future. Past evolution of the groundwater resource are difficult to assess due to the short observation period. Similar methods are used to treat past and future : climate modeling, downscaling method, and hydrogeological modeling. However, observation availability in the past help driving and assessing the XXth groundwater evolution. Results obtained with the Aqui-FR modeling in France will be shown

16:30
Poster 4. Foam flows in porous media: preferential paths, intermittency and non-stationary bubble size distribution
SPEAKER: Yves Meheust

ABSTRACT. The use of foams for subsurface remediation takes advantage of their peculiar flow properties, which we study using a two-dimensional setup in which the foam structure and bubble velocities are monitored. We uncover a rich phenomenology, where larger bubbles follow preferential paths of higher velocities, the flow is locally intermittent under stationary forcing, and bubble fragmentation leads to an irreversible evolution of the foam's bubble size distribution. We decipher the theoretical link between that evolution and individual bubble fragmentation events.

16:30
Poster 5. Application of a model for point-wise prediction of stream flow statistics using climatic and geomorphologic data to Taiwan
SPEAKER: Igor Lisac

ABSTRACT. We have investigated how spatial variability in rainfall within a given catchment, as for example seen in mountain environments affected by orographically-controlled precipitation, affects the relationship between the characteristics of rainfall variability and those of the water discharge in the river. For this, we have applied to data from Taiwan a model developed by Doulatyari et al. (2017) that uses properties of the surface network and topography to relate spatial variability in rainfall to spatial variability in discharge.

16:30
Poster 6. A Finite Volume Discretization Approach to Solving Flow of Groundwater and Tracer Transport in Karst Aquifers
SPEAKER: Md S. Jamal

ABSTRACT. In this paper, we model the flow of nonreactive tracers in karst reservoirs by coupling the continuity equation, the Brinkman’s equation to the Advection-Diffusion-Adsorption equation. The flow of fluid is modelled as single-phase, slightly-compressible flow by solving the continuity equation and the Brinkman’s equation simultaneously to obtain the pressure and velocity distribution in the entire reservoir. Using the computed velocity distribution, the Advection-Diffusion-Adsorption equation is then solved numerically to model the transport of the tracers through the reservoir.

16:30
Poster 7. Transient times as a tool to resolve “hot moments“ of nitrogen transformations at a mixed land use catchment

ABSTRACT. Resolving the nitrogen sources in river discharge and the “hot moments” of nitrogen transformations at river catchment is crucial in attempts to reduce nitrogen export. Transient time information can be utilized to find these „hot moments“. We use particle tracking of stable water isotopes within a hydrological model to retrieve water travel times and use the information to analyze nitrogen transport and to spot relevant times of nitrate formation within a mixed land use catchment (10 km²).

16:30
Poster 8. Characterisation of two-phase flow within channels of PEM water electrolysis cells

ABSTRACT. Commonly, Darcy scale models are adopted to investigate the removal of gaseous waste products within electrolysis cells. In contrast, we model the two-phase flow within cell channels on the bubble scale. To this end, direct numerical simulations are conducted by adopting smoothed particles dynamics. Results concerning limitations and parametrizations of Darcian scale models will be presented. Moreover, channel flow properties are detected which affect the channels’s gas uptake from porous cell components.

16:30
Poster 9. Numerical Modelling of Poroelasticity in Fractured Rock
SPEAKER: Jan Stebel

ABSTRACT. We present a mathematical model of hydro-mechanical interaction based on the Biot system in a fractured rock. The fracture can be void or filled by an elastic material. We perform dimension reduction of the equations in the fracture and obtain averaged flow and elasticity equations coupled with the equations in the rock through interface conditions. For nearly incompressible materials a mixed formulation of the linear elasticity is used. We further study stability of finite element formulations and of iterative splittings.

16:30
Poster 10. Flow distributions and spatial correlations in mice brain microvascular networks
SPEAKER: Goirand

ABSTRACT. The mouse brain vascular system is composed of a space-filling capillary network connected to branched quasi-fractal arterioles and venules. We investigate the distribution and correlation properties of blood flow velocities from numerical simulations in this system. Flow is solved from a 1D non-linear model taking account of the complex rheological properties of blood flow.

The network structural complexity imparts broad and spatially correlated Lagrangian velocity distributions, leading to power law transit time distributions. The origins of this behavior are studied.

16:30
Poster 11. A new fully distributed model of nitrate transport and removal at catchment scale

ABSTRACT. We present a new flexibly designed, fully distributed nitrate transport and removal model (mHM-Nitrate) at catchment scale. The model was developed mainly based on the mesoscale Hydrological Model (mHM) and the Hydrological Predictions for the Environment (HYPE) model. The mHM-Nitrate model was tested in the Selke catchment (Central Germany), which is characterized by heterogeneous physiographic and land-use conditions, using adequate observed hydrological and nitrate data at three nested gauging stations. Long term (1997-2015) daily simulations showed that the model well reproduced the seasonal dynamics of biweekly nitrate observations in forested, agricultural and urban areas. High-frequency measurements (2010-2015) were additionally used to validate model performance of simulating short-term changes in stream-water concentrations that reflect changes in runoff partitioning and event-based dilution effects.

16:30
Poster 12. Composition of spring and deep borehole waters in the granitic Ringelbach research catchment (Vosges Mountains, France): contribution of a hydrogeochemical modeling approach
SPEAKER: Yann Lucas

ABSTRACT. We present the results of the hydrogeochemical modeling of the geochemical compositions of spring and borehole waters from the Ringelbach catchment (Vosges Mountains, France). The simulations, using the hydrogeochemical code KIRMAT, were performed through two different water pathways in different types of rocks and make it possible to account for not only the geochemical differences between the spring and borehole waters but also the geochemical variations observed in waters in both contexts.

16:30
Poster 13. Flow structures and hydraulic property scalings in fractured sedimentary rock revealed by a large-scale pumping test

ABSTRACT. A pumping test conducted in a faulted formation provides consistent scalings of transmissivity and storativity over a few hundred meters. Drawdown analysis shows persistent reductions of transmissivity in two structures. The linear dependency of transmissivity to storativity indicates a fractured damage zone while the cubic dependency identifies well-defined faults. The latter demonstrates the validity of Poiseuille flow at a rarely investigated scale. Well-designed pumping tests and scaling analysis thus provide essential information on flow-bearing structures for site characterization and modeling.

16:30
Poster 14. Quantifying the contributions of root systems to individual and community drought resilience in the Amazon rainforest

ABSTRACT. The increased intensity and severity of droughts within the Amazon Basin region has emphasized questions of vulnerability and resilience of tropical forests to water limitation. In this work, we utilize a three-dimensional model of root water uptake to explore and quantify the contributions of tree root systems to individual and community drought resilience. The model is informed by data collected during the 2015-2016 El Niño drought period from the Tapajós National Forest, Pará, Brazil.

16:30
Poster 15. How sustainable is groundwater abstraction? A global assessment.

ABSTRACT. Already groundwater abstraction often exceeds groundwater recharge, leading to groundwater depletion. Here we explore the limits to global groundwater consumption for the first time by evaluating effects of head declines on natural groundwater baseflows and groundwater accessibility. We show that negative effects on groundwater baseflows are often experiences first and also for regions not know for significant depletions or head declines. Regionally the increasing level of groundwater stress will be an important factor in future economic development and socio-economic environment.

16:30
Poster 16. Simulating the Development of Weathering Profiles in Shale Bedrock at the Eel River Critical Zone Observatory
SPEAKER: Jia Wang

ABSTRACT. We report the use of 1 and 2D reactive transport simulations to quantify the development of weathering profiles in a dual flow domain fractured argillaceous bedrock. The models uniquely quantify weathering patterns across a variably saturated hillslope within the Eel River Critical Zone Observatory in Mendocino County, California. The validity of the models is demonstrated by comparison to novel direct measurements of solute concentrations from aqueous samples extracted throughout the fractured vadose zone.

16:30
Poster 17. Scale Effects in the Flow of a Shear-Thinning Fluid in Geological Fractures
SPEAKER: Yves Méheust

ABSTRACT. We investigate how fracture wall roughness impacts the flow of a shear-thinning fluid. Numerical simulations of flow in 3D geological fractures are carried out by solving a modified Navier-Stokes equation incorporating the Carreau viscous-shear model. The objective is to investigate how varying the correlation length impacts the flow behavior, for different degrees of closure, and how this behavior diverges from Newtonian fluids. The results from the 3D simulations are also compared to 2D simulations based on the lubrication theory.

16:30
Poster 18. Fluid viscosity controls earthquakes nucleation

ABSTRACT. Understanding the effects of the viscosity of fluids on fault mechanics can shed light on the seismicity in engineering reservoirs induced by the injection of pressurized fluids. Here, we investigate precursory patterns and we explore general stability criteria for earthquake nucleation in presence or not of viscous fluids, using a rotary shear apparatus in laboratory experiments.

16:30
Poster 19. Kinematic metric to quantify fast reactions in transport through heterogeneous media

ABSTRACT. The local rate of stretching of an imaginary filament in a heterogeneous flow is linked to the rate of dilution of a conservative scalar. By linking the rate of dilution to the reactivity for fast reactions, we arrive at a method to understand how the heterogeneous structure affects locally the reaction rates. While yielding identical particle trajectories, the residual divergence, small yet finite, causes significant deviations in the rate of stretching, and thus, the prediction of the reactivity.

16:30
Poster 20. Improving US national water modeling: an intercomparison of two high-resolution, continental scale models, ParFlow-CONUS and National Water Model configuration of WRF-Hydro

ABSTRACT. Continental scale hydrology models at high spatial resolution are increasing in application. We compare models developed for the continental US: ParFlow-CONUS using the integrated model ParFlow and a configuration of the National Water Model using the National Center for Atmospheric Research, Weather Research and Forecasting hydro extension package. Accurately representing large domains remains a challenge considering the difficult task of representing complex hydrologic processes, computational expense, and extensive data needs. Intercomparing both models helps disentangle process, parameter, and formulation differences.

16:30
Poster 21. An Upscaled Rate Law For Magnesite Dissolution in Heterogeneous Media
SPEAKER: Hang Wen

ABSTRACT. Mineral dissolution rates measured in natural systems have long been observed to be lower than those measured in well-mixed reactors by 3–6 orders of magnitude. This work develops a general rate law for magnesite dissolution in heterogeneous media under variable flow velocity and length scale conditions through the connections between rate constants at well-mixed reactors, spatial heterogeneity, and timescales in both reactive zones and the whole domain.

16:30
Poster 22. Toward a forecast model for a water table control system in cranberry production
SPEAKER: Cintia Racine

ABSTRACT. The scope of this study is to develop a forecast hydrological model at the field scale, able to simulate water level and soil tension in the roots zone for water table control operations. In this work, the finite element CATHY (CATchment Hydrology) model associated with sequential data assimilation with an ensemble Kalman filter (EnKF) method will be used to simulated the soil water dynamics and perform model calibration in real-time. The study is conducted in cranberry fields located in Canada.

16:30
Poster 23. Formation and drop control in modeled porous media
SPEAKER: Mario Cachile

ABSTRACT. Production and transport of oil drops in micro as well as millimetric channel is studied. Two simple model porous media were considered. First, made with a capillary tube with a controlled constriction in the middle, modeling pore - throat system. The second, is a bifurcation, which models local distribution at pore scales. Both systems were are wetted by oil. The size and distribution, splitting and coalescence of drops were studied as a function of water and oil flow rates.

16:30
Poster 24. Characterizing Canadian Shield Fractured Crystalline Rock Settings Using Geochemistry

ABSTRACT. The evolution of groundwater system geochemistry in a fractured Canadian Shield crystalline rock setting is explored through a series of numerical experiments in which both model hydraulic and transport properties are varied. The degree of importance of both matrix and fracture zone hydraulic properties to the geochemical evolution of the groundwater system is demonstrated through the use of performance measures such as groundwater age, mean life expectancy, and salinity distributions in both the rock mass and discrete fracture zone network.

16:30
Poster 25. Modelling transport of sorbed species in clays

ABSTRACT. Contaminant migration through clays mainly occurs by diffusion and is affected by sorption. Experimental diffusion data often shows that cation diffusion coefficients are higher than diffusion coefficients of water tracers. In order to account for that discrepancy a surface diffusion model is set up in the reactive transport code FLOTRAN. The model accounts for a partial mobility of sorbed cations. First results for Cs diffusion in Opalinus Clay show that the model is able to describe the experimental data consistently.

16:30
Poster 26. Closing the conceptual gap between the hyporheic zone and the river corridor

ABSTRACT. We aim to provide and integrate field and modelling approaches to overcome the conceptual gap between the hyporheic zone and the river corridor across different spatial and temporal scales. This is indispensable for understanding and quantifying biogeochemical turnover. Numerical models simulating both the hyporheic and stream system will allow quantifying exchange fluxes and processes across the different spatial and temporal scales. These models will be based on a high-resolution LIDAR-UAV streambed and will integrate tracer -and UAV- based data.

16:30
Poster 27. Evaluation of a physically-based base flow time constant in ORCHIDEE Land-Surface Model at global scale
SPEAKER: Ana Schneider

ABSTRACT. In this work we estimate the base flow time constant at global scale by using an analytical solution of the Boussinesq equation for a homogeneous, isotropic, linear reservoir that depends on the effective porosity, transmissivity, drainage density and slope. Different literature values of hydrogeological parameters were tested, and the results that are closest to references from river discharge observations were evaluated in the groundwater reservoir of the ORCHIDEE Land surface Model.

16:30
Poster 28. A transient approach to modeling isotopic equilibration during water-rock interactions

ABSTRACT. In chemical weathering environments the balance between reactivity and transport govern the extent of fluid-rock interactions. In such systems, the common method of treating isotope fractionation using irreversible rates fails to capture the dynamic balance between both kinetic and equilibrium fractionation and transient shifts between them as a function of transport. A transient model involving coupled fluid and solid phase isotopic compositions is used to describe silicon isotopic equilibration during amorphous silica precipitation with applicability to interpretation of weathering fluxes.

16:30
Poster 29. Poroelasticity analysis of a hydraulically fractured shale rock formation
SPEAKER: Miad Jarrahi

ABSTRACT. This study was performed to examine the coupled hydro-mechanical process during hydraulic fracturing in a typical shale rock formation, embedding a system of well-behaved, horizontal plate-like natural fractures. The Stimulated Reservoir Volume modelling technique was integrated with the finite element approach to simulate a 3-D poroelastic porous matrix. The computations were done through a quasi-transient simulations for eight different hydro fractures radius. The corresponding numerical method was verified versus the benchmark model of Wendland and Himmelsbach.

16:30
Poster 30. An approach based on a groundwater flow model and a geomechanical model for estimating thermal anomalies locations

ABSTRACT. In geothermal exploration, the potential to locate thermal anomalies is compromised in some “blind” geological contexts (lack of thermal information at depth and of surface manifestations). We propose an approach to help locating thermal anomalies based on a groundwater flow model and a geomechanical model. The approach incorporates a thorough structural analysis to build the models geometry (Discrete Fracture Network) and a cross-analysis of models results to estimate areas where the physical conditions are expected to favor thermal anomalies.

16:30
Poster 31. Coupled Electro-hydrodynamic Transport in Geological Fractures
SPEAKER: Uddipta Ghosh

ABSTRACT. Transport properties of rock formations are dictated by the behaviour of fracture networks. Noting that the effect of electrical properties of fracture walls on the flow dynamics remains an open question with potentially significant implications, here, we explore the coupled electro-hydrodynamic transport in the same using a generalized version of lubrication theory assuming specified hydraulic head, electrical potential and concentration across the fracture. The resulting system of equations is solved using an iterative Finite-Volume-Method for realistic aperture fields.

16:30
Poster 32. Response of the simulated climate to the sub-grid scale variability of the water table depth: evidence of non-linear amplifications in the IPSL climate model.

ABSTRACT. This study focus on the impacts of a shallow water table in the climate model of the IPSL. A sensitivity experiment was performed by carry out global simulations with different fractions of each grid-cell occupied by a prescribed saturated zone below 1m. We highlighted a non-linear response of the near surface climate due to the coupling between land and atmosphere models, with strongest variations where shallow water table fractions are weak.

16:30
Poster 33. Multiscale analysis of biofilm and tissue mechanics via the method of volume averaging

ABSTRACT. The mechanics of cellular systems is complex, in part because the materials themselves are difficult to characterize, and in part because there can be biological feedbacks between biofilm properties and applied stresses. We present a first effort for formally homogenizing the mechanics of such systems using the method of volume averaging. Our starting point is a simplified model containing cells, an extracellular matrix, and a constitutive law describing how cells respond to induced stresses.

16:30
Poster 34. Understanding couplings between transport mechanisms and biofilms in porous media using 3D printed micro-bioreactors and X-ray imaging

ABSTRACT. We present a novel experimental system based on a fully instrumented 3D printed fluidic micro-bioreactor. We demonstrate how, combined with X-ray microtomography, this system can quantify biofilm distribution in pore-space for different growth conditions. 3D printing further allows for porous structures with known properties (porosity, permeability and pore size) to be precisely replicated. This makes it possible to vary one parameter (e.g. flow rate and nutrient concentrations) and to reveal its influence on the biofilm architecture inside the porous network.

16:30
Poster 35. The Hydrochronology and Water Storage of the Southern Sierra Critical Zone

ABSTRACT. Solute transport within catchments is controlled by how the critical zone selects water from storage for discharge or evapotranspiration. This study investigates the storage selection of the Southern Sierra Critical Zone Observatory, which we constrained by a novel combination of cosmogenic radioactive and stable isotopes: tritium, sodium-22, sulfur-35 and oxygen-18. The derived water storage and travel times are related to the weathering rates and measured solutes in the catchment.

16:30
Poster 36. Long-term chemical evolution of hard rock aquifers related to exploitation : Anthopocene revealed from observatories.
SPEAKER: Aquilina Luc

ABSTRACT. Hard rock aquifers are known as highly compartmentalized structures. The chemical composition of groundwater reflect this compartimentalization including anoxic groundwater with long residence time in the lower section. These deep groundwater have recorded long-term climatic changes. Exploitation induces the propagation of modern pollutants downward and increases mineral dissolution and biogeochemical reactivity such as denitrification. Long term monitoring in the H+ network have shown the limits of anthropogenic influences in these aquifers.

16:30
Poster 37. Analysis of Soil Hydraulic and Thermal Properties for Land Surface Modelling over the Tibetan Plateau
SPEAKER: Hong Zhao

ABSTRACT. To obtain an explicit insight into the soil hydro-thermal consistency for land surface modelling over the Tibetan Plateau (TP), in situ and laboratory measurements of over 40 soil property profiles were obtained across three dominant climate zones (i.e. arid, semi-arid, and semi-humid). Parameterization schemes for porosity, soil hydraulic and thermal properties were investigated. Using the superior parameterization schemes, the uncertainties of five existing soil datasets and their derived soil hydraulic and thermal properties over the TP were quantified.

16:30
Poster 38. Derivation of a bedload transport model with viscous effects

ABSTRACT. We aim at proposing a new bedload transport model without closure relationship. Our model is deduced from a fluid-like description of the sediment layer. It is obtained by performing simultaneously the Shallow-Water approximation and the diffusive limit in the Navier-Stokes equations. Dierent scalings of the viscosity coecient allow to obtain an equation for the sediment velocity with or without viscous term. Numerical experiments illustrate the novelty of the model.

16:30
Poster 39. A combination of high resolution hydro-sedimentary data and distributed numerical modelling to understand internal catchment erosion processes

ABSTRACT. A high resolution data set on discharge, precipitation, suspended sediment concentration as well as quantified sediment source contributions obtained with fingerprinting in two-meso scale Mediterranean catchments is used in combination with a distributed numerical model in order to assess the impact of connectivity on suspended sediment fluxes. The hydro-sedimentary model is set up in Iber, a 2-D hydrodynamic model that solves the St. Venant equations and is completed with a soil infiltration module and an erosion model.

16:30
Poster 40. Morphodynamic modelling of landslide evacuation in bedrock rivers

ABSTRACT. The timescales and mechanisms by which rivers evacuate landslide deposits are poorly known, but are critical for predicting geomorphic hazards and determining the role of extreme events on landscape evolution. Here, we use a numerical model of river evolution accounting for the morphodynamic feedbacks between river transport capacity and changes in river geometry, initially perturbed by the potentially large landslide deposits. Our simulations evidence the previously unrecognized role of river dynamic narrowing in significantly accelerating the removal of landslide deposits.

16:30
Poster 41. Benchmarking Multilayer-HySEA model for landslide generated tsunamis
SPEAKER: Jorge Macias

ABSTRACT. The Multilayer-HySEA model including non-hydrostatic effects has been used to perform all the benchmarking problems dealing with laboratory experiments proposed in the workshop that was organized at Texas A&M University - Galveston, on January 9-11, 2017 by NTHMP. The aim of this presentation is to show some of the latest numerical results obtained with the Multilayer-HySEA (non-hydrostatic) model in the framework of this validation effort.

16:30
Poster 42. Coupling topo-bathymetric lidar and 2D flood modelling to invert spatial patterns of friction in rivers
SPEAKER: Dimitri Lague

ABSTRACT. Topo-bathymetric lidar can now map water surface and river bathymetry at very high accuracy (5-10 cm), resolution (> 10 pts/m²) and over large areas (> 10 km). We use a reduced complexity 2D flood model and knowledge of the discharge to invert for spatial patterns of the Manning friction coefficient in various rivers. Systematic spatial variations are observed. The relationship to bed lidar roughness is explored to evaluate if bed friction can be computed from topo-bathymetric lidar data.

16:30
Poster 43. Formulation of the 3D Shallow Water and 3D/2D Coupled Shallow Water Models in the Adaptive Hydraulics Suite
SPEAKER: Corey Trahan

ABSTRACT. The Adaptive Hydraulics (AdH) software suite is a state-of-the-art modeling system developed by ERDC, USACE. AdH is an adaptive and implicit finite element suite containing models for 2D and 3D shallow water (SW) dynamics and salt, sediment and general transport. This presentation will focus on the formulation and implementation of the AdH SW 3D stand alone baroclinic model and 2D/3D SW coupling. Validation results will be shown for both stand-alone and coupled results.

16:30
Poster 44. Daily spatial groundwater table dynamics over a 15-year period from monthly time series of different lengths
SPEAKER: Eric Laloy

ABSTRACT. Groundwater table behaviour in shallow aquifers is often more dynamic than one would expect from monthly groundwater level observations. Moreover, spatial patterns of groundwater flow can vary considerably throughout the seasons, and may even be influenced by single rainfall and corresponding recharge events. We investigate the typical temporal and spatial groundwater table behaviour at the ONDRAF/NIRAS Mol/Dessel site, and quantify the daily spatial groundwater table dynamics over a period of 15 years, based on monthly time series.

16:30
Poster 45. Multiphase fluid flow modeling of chlorinated solvents infiltration in fractured clay till

ABSTRACT. In this work, the infiltration of chlorinated solvents underground is modelled using a dual porosity single-permeability multiphase transport formulation. The model considers a fractured, clay-rich vadose zone overlying a sandy aquifer. The results predict that once the infiltration is stopped, most contaminant is already settled down at the bottom of aquifer, remaining mainly at the dead-end of fractures in the vadose zone. At longer times, back-diffusion drives the release of contaminant to the aquifer.

16:30
Poster 46. Revisitation of the dipole tracer test for heterogeneous porous formations
SPEAKER: Alraune Zech

ABSTRACT. An analytical solution for interpreting dipole-tests in heterogeneous media is presented. It is shown how the solution can be used for interpreting field tests in view of geostatistical aquifer characterization on some illustrative examples. The analytical solution for the tracer breakthrough curve at the pumping well is developed by considering a perfectly stratified formation and associating the shape of the BTC with the log-conductivity variance. Solutions are presented for resident/flux proportional injection and for instantaneous/continuous solute injections.

16:30
Poster 47. Simulating the variability of surface saturation generation in a forested catchment

ABSTRACT. In this study we use the integrated surface subsurface model HydroGeoSphere for simulating the generation of surface saturation within a small (45 ha) forested catchment. We compare the simulated surface saturation patterns and dynamics of several locations distributed over the catchment with repeated field mappings of surface saturation at these locations. The comparison demonstrates the potential of the model to reproduce the spatial and temporal variability of surface saturation and helps to identify the underlying surface saturation generation processes.

16:30
Poster 48. A modern software approach to improve the computational efficiency of the integrated hydrological model GEOtop
SPEAKER: Bortoli Elisa

ABSTRACT. Integrated hydrological modeling systems simulate complex interactions between groundwater, surface water flows, vegetation and atmosphere under heterogeneous conditions. Therefore, the developed codes are often not easy portable and difficult to be handled. Moreover, the application such models to large domains or long time series requires significant computational efforts. We present our recent software re-engineering efforts of the GEOtop model to create a robust and computationally efficient scientific software package open to the hydrological community, easily usable by researchers and experts.

16:30
Poster 49. Modeling leaf-phenology in Amazonia: impacts on carbon and water fluxes

ABSTRACT. A novel mechanistic model of tropical leaf-phenology, reconciling observations of dry season greening and water stress in Amazonia, is presented. The model accounts for leaf development, synchronized dry season litterfall and the effect of leaf quality and quantity on leaf photosynthetic capacity. Simulation results from 32 sites in the Amazon basin over a 15-year period reveal that leaf phenology explains carbon fluxes seasonality but the impact on evapotranspiration is limited due to compensatory effects of canopy-atmosphere decoupling and LAI dynamics.

16:30
Poster 50. Modeling the hydrological response of different tree line vegetation in Central Himalaya, India
SPEAKER: Rajesh Joshi

ABSTRACT. In this study rainfall-runoff-soil loss relationship were modeled for three prominent vegetation types in tree line zone of Central Himalaya in India. Nine experimental plots (10mx5m) were delineated on three prominent vegetation types, viz; Coniferous forests, Krumholz, and alpine grassland. Using stochastic and soft computing models, an empirical relationship was developed to simulate rainfall-runoff- soil loss and hence to estimate soil erosion from tree line vegetation in central Himalaya; these findings will lead towards devising better conservation and management strategies.

16:30
Poster 51. Analysis of persistent seismic multiplets at the EGS reservoir of Soultz-Sous-Forêts, France

ABSTRACT. The induced seismicity at the Enhanced Geothermal System of Soultz-Sous-Forêts in France has been related to both fluid pressure increase during stimulation and aseismic creeping movements. The fluid-induced seismic events often exhibit a high degree of similarity and the mechanism at the origin of these repeated events is thought to be associated with slow slip processes where asperities rupture several times. We investigate the sources of such events to decipher the link between multiplets and aseismic slip.

16:30
Poster 52. Fluid thermodynamics control induced earthquake ruptures.
SPEAKER: Marie Violay

ABSTRACT. To understand hydro-mechanical couplings between fluid and fault rocks during earthquake rupture, we performed laboratory earthquakes at conditions representative of Enhanced-Geothermal-Reservoirs (Stress, Fluid Pressure, Lithology). We observe that fluid pressure level controls dynamic fault heating and weakening trough fluid's phase transitions which can act as heat buffers. Our experimental observations, supported by microstructures and simplified models of temperature rise in the fault led to an understanding of the weakening mechanisms during dynamic earthquake rupture in presence of fluids.

16:30
Poster 53. Impact of large erosional events on seismic cycle

ABSTRACT. Large typhoons or earthquakes trigger numerous landslides and produce large volumes of sediments that are exported by rivers in years to decades. This surface unloading could induce stress changes at depth and trigger shallow seismicity. We use the QDYN numerical model to investigate the effects of time-dependent variations of stress rate on faults activity. Our results show a step-like increase of earthquake frequency following a normal stress decrease, which is most significant if river transport occurs within a few years.

16:30
Poster 54. Mixing and reactions: The case of Taylor dispersion in a tube
SPEAKER: Brian Wood

ABSTRACT. In this work, we extend some previous analyses of mixing an reaction under transient conditions to the simple case of Taylor dispersion and reaction in a tube. This geometry has provided an archetype for understanding dispersion in porous media for more than 70 years, and here we consider that analysis for the case of reacting fluids. In particular, we examine how the configuration of the initial condition influences the resulting effective rate of reaction.

16:30
Poster 55. From sequential homogenization to multiscale data reconstruction

ABSTRACT. Direct numerical simulations of pore-scale flow and transport in porous media require the knowledge of pore-space topology. Real porous systems, e.g. rocks, pose additional challenges since they usually exhibit multi-modal distributions in physical and chemical properties. These hierarchical media cannot be approached by a single continuum formulation. We discuss both the approximation of sequential homogenization approaches and propose an algorithm of downscaling followed by segmentation to reconstruct the unresolved pore space from XCT images of natural polydisperse geological porous media.

16:30
Poster 56. Chemical Continuous Time Random Walks
SPEAKER: Tomas Aquino

ABSTRACT. Simulating reactive transport at the large scale requires upscaled frameworks where local incomplete mixing must be acknowledged. Departing from continuous time random walk theory, we extend classical Kinetic Monte Carlo theory to account for arbitrary inter-reaction times representing incomplete mixing, providing a generalized Gillespie algorithm. Our approach efficiently simulates generalized Michaelis—Menten kinetics and time-nonlocal kinetics exhibiting weak ergodicity breaking. We introduce a hybrid framework that models transport through a Lagrangian random walk and local-scale reactions through our generalized framework.

16:30
Poster 57. Mathematical model of Fast High Volume Infiltration into Subsurface

ABSTRACT. Fast high volume infiltration (FHVI) is a technique to inject high volume of water into subsurface in a short span of time. During periods of heavy rainfall or dewatering of sites of construction large volume of water is available which can effectively be used in future if stored. The conventional infiltration techniques cannot achieve FHVI. The present study mathematically models the FHVI process. The model results are compared with that of a numerical model and also an experimental field study.

16:30
Poster 58. Marine and continental controls of groundwater flooding in coastal areas

ABSTRACT. Groundwater flooding is a critical issue in relatively flat coastal areas like along the coasts of Normandy (Western France). Starting from field observations, we build a numerical groundwater flow model of a coastal aquifer near Bréville-sur-Mer (Normandy, France). We show that while tidal variations have a limited influence, the mean sea level rise may induce significant groundwater table elevations. Local topographical depressions through their capacity to offer natural drains may significantly alleviate flood vulnerability and present key structures.

16:30
Poster 59. Opening versus self-sealing behavior of single fractures in mudstone caprocks during CO2 migration
SPEAKER: Niko Kampman

ABSTRACT. CO2-induced reactions in fractured mudstone include mineral dissolution/precipitation, clay swelling reactions, and CO2-exsolution promoted mineral precipitation; the progress of these reactions controls fracture opening versus self-sealing behavior. We investigate the controls on fracture opening versus self-sealing for synthetic vertical single rough walled fractures with self-affine fracture surfaces, using 2.5D reactive transport modeling simulations. The impact of mineralogy, aperture distribution, fluid residence time and poro-elastic effects on fracture opening versus self-sealing behavior is investigated for single and two phases flows.

16:30
Poster 60. Investigating the influence of aperture variability on the fracture surface area in enhanced geothermal reservoirs

ABSTRACT. To estimate the performance of enhanced geothermal systems (EGS) an accurate characterization of the created fracture networks is crucial. One of the most relevant parameters for heat extractions is the fracture surface area. However, it is also one of the major uncertainties in the characterization of fractured reservoirs. Here, we perform numerical simulations to investigate the influence of heterogeneous aperture distribution on fracture surface area and its implication for the results of tracer tests.

16:30
Poster 61. A conceptual and numerical approach for modeling reactive transport in Discrete Fracture Networks
SPEAKER: Elena Abarca

ABSTRACT. A challenge in modelling reactive transport in discrete fractures is how to conceptualize the matrix-fracture interface. We present an approach that solves reactive transport in discrete fractures and the porous matrix independently but couples them through mass transfer terms. Its implementation in iCP (interface Comsol-Phreeqc) is validated against analytical and numerical solutions for flow and transport. We apply it to model calcite precipitation in fractures driven by mixing between granitic waters and pore water from concrete leaching.

16:30
Poster 62. A finite-volume based discrete fracture model for non-isothermal flow and transport in fractured porous media

ABSTRACT. This work presents a discrete fracture model on the basis of a cell-centered finite volume approach, where the fractures are modeled as lower-dimensional geometries. The scheme allows for an explicit evaluation of matrix-fracture transfer fluxes and is able to represent jumps in solution and fluxes across the fractures. First, we examine the performance of the model for complex flow processes on simple geometries by comparing the results to an equi-dimensional discretization. Subsequently, it is applied to complex fracture networks.

16:30
Poster 63. Effect of roughness on solute transport through synthetic rough single fractures
SPEAKER: Zhou Chen

ABSTRACT. Understanding solute transport in fractured rocks is of particular importance in many applications. This paper focused on the dispersion process in rough single fractures under non-Darcian flow conditions. Non-Darcian flow existed in both smooth and rough single fractures and were best described by the Forchheimer equation.The ADE model failed to capture the long-tailing of breakthrough curves (BTCs). Instead, the CTRW model could better explain BTCs in both smooth and rough fractures, especially in capturing the long-tailing feature

16:30
Poster 64. Dynamics of reactive microbial hotspots in concentration and velocity gradients

ABSTRACT. Natural nutrients fluxes and solute concentrations needed for bacteria metabolism may be highly variable in space and intermittent in time. Reactive hotspots induce biogeochemical reaction kinetics that differ significantly from homogeneous model environments. We develop microfluidic devices to produce single and double concentration gradients, allowing for quantitative monitoring of the bacteria's spatial distribution and early-stage biofilm development. We investigate the influence of chemical and velocity gradients on biogeochemical reactions kinetics, biomass production, and we develop growth models.

16:30
Poster 65. Can 18O of lakes be used to measure lake water residence times? Simulation of groundwater-lake interactions and lake water budgets at the catchment scale

ABSTRACT. An integrated 3D catchment-scale groundwater-stream-lake model was developed and calibrated using PEST. The aim was to derive the water budgets and lake water residence times (T) for 13 lakes in two neighboring catchments. Water stable isotopes were used to derive a 18O – T relationship in order to investigate if 18O in lakes can be used to estimate residence time. The results are encouraging, but work best for T < 2-3 years.

16:30
Poster 66. Effect of streamline distribution and mixing on reactive processes at the hillslope scale

ABSTRACT. Subsurface flow patterns exert a significant influence on solute transport and biogeochemical processes for a broad range of scales. Consequences on solute turnover and chemical weathering is usually addressed by residence time distribution approaches. However, understanding streamline spatial patterns impact and the effect of mixing across streamlines on reaction kinetics remains an outstanding challenge. Here, we investigate the impact of surface topography on subsurface streamline patterns and analyse their influence on mixing and reaction processes for different biogeochemical reactions.

16:30
Poster 67. Investigating the dynamics of transit times and subsurface mixing of a small agricultural catchment using physically-based numerical model
SPEAKER: Jie Yang

ABSTRACT. We explore the dynamics of transit times and subsurface mixing in the small agricultural catchment Schäfertal, Central Germany. We use a 3D fully coupled surface-subsurface hydrological model to simulate water flow, and particle tracking to track flow paths and calculate the transit times of water parcels. The catchment-scale transit time distributions, residence time distributions and fractional StorAge Selection functions are computed and evaluated in terms of the transient, seasonal nature of median transit/residence times and discharge selection preferences.

16:30
Poster 68. Upscaling reactive flow and transport in an evolving porous medium
SPEAKER: Nadja Ray

ABSTRACT. We consider porous media applications that contain evolving solid phases. Deriving models that describe such structural changes at a variety of scales is essential to understanding the intimate linking between structure and function. With reference to the soil's heterogeneity, we aim to develop a mathematical model at the pore scale, perform its upscaling to transfer our model from the small scale to the macroscale and investigate the resulting model numerically.

16:30
Poster 69. A dynamic modeling procedure for estimating flow-induced seismicity in fluid-saturated faults

ABSTRACT. The paramount role of pore fluid pressure during earthquake nucleation and dynamic rupture deserves further comprehension. Earthquake ruptures in poroelastic media encompass complex phenomena, including stick-slip frictional instabilities, thermal processes and hydromechanical couplings. A numerical simulation that couples fault poromechanics, rock poroelasticity and inertial effects is required in order to understand the elastodynamic issues on the rupture of induced earthquakes. Our numerical model includes fully-coupled hydromechanical, frictional and dynamic features; analyses the effects of both poroelasticity and the viscous material properties on the characterization of injection-induced earthquakes. We assume a rate-and state-frictional law for the fault and the Kelvin-Voigt constitutive model for the rock. We simulate the whole earthquake sequence, both the interseismic and dynamic rupture phases, and quantify the differences between the rupture events whether the dynamic approach is considered or not. So we elucidate the key question of whether quasi-dynamic models are able to faithfully reproduce the main features of induced earthquakes obtained in dynamic simulations. The viscoelastic constitutive relation for the solid domain implies a dissipative term that affects the overall response and allows us to simulate the physical process of seismic wave attenuation. Furthermore, viscous dissipation avoids spurious high-frequency oscillations during wave propagation. The inclusion of inertial terms enables the model to account for the incremental fluctuations of both pore pressures and the stress field during dynamic rupture, which may shed light on the mechanisms that control the dynamic triggering on nearby faults.

16:30
Poster 70. Reactive Modeling in Porous Media with an Innovative Dual Mesh Method

ABSTRACT. We propose an original algorithm for a compositional flow modeling in porous media with rock-fluid interactions using two different space and time discretization: one mesh, as usual for the pressure equation and a much finer one for the chemical reactions. The interest of this scheme is that the calculation of the flow on the high resolution grid is done solving a local problem on each coarse grid. This step is easily solved on parallel machines. The transport of species are done on the high resolution mesh using an explicit scheme which is also easy to solve on a parallel machine. The time step and the well indexes for the transport on the high resolution mesh is of course adapted to this explicit scheme. Two examples will illustrate this algorithm: one for an injection of CO2 in a carbonate reservoir and the second one will address reactions during the injection of an acidic water for improving well injectivity again in a carbonate reservoir.

16:30
Poster 71. Mapping groundwater recharge using the relationship between the IDPR and baseflow indexes
SPEAKER: Sandra Lanini

ABSTRACT. A gridded water budget model was developed to compute the groundwater recharge with a resolution of 8 km and a daily time step. Three different water budget methods were included to assess the uncertainty associated to the effective rainfall parameterization method. We then proposed a global solution to split the effective rainfall between runoff and infiltration, relying on a GIS built parameter called IDPR. A linear relationship between the BFI and the spatial average IDPR index was proved for the sedimentary basins. It thus allowed calibrating the IDPR index in terms of infiltration capacity. Finally, groundwater direct recharge could be calculated and annual average recharge maps were generated.

16:30
Poster 72. Behaviour of Bingham fluid in heterogeneous porous media

ABSTRACT. We study statistical properties of a Bingham fluid in macroscopic porous media generated with a log-normal distribution. We find multi-scale properties characterised by exponents. We also find an unexpected flow rate as a function of the relative pressure. We explore the exponents and give an explanation for this specific flow regime.