1. Earth Sciences Sector Groundwater Mapping 1 GROUNDWATER MODELLING: FROM GEOLOGY TO HYDROGEOLOGY Alfonso Rivera Chief Hydrogeologist Geological Survey of Canada GSA Annual Meeting Denver, CO, USA October 28-31 2007

2. Earth Sciences Sector Groundwater Mapping 2 GROUNDWATER MODELLING: FROM GEOLOGY TO HYDROGEOLOGY OUTLINE Modelling Geology mapping-Groundwater modelling links Approaches to Groundwater Modelling Examples of Models developed by the GSC Groundwater Analysis & Simulation types Towards an integrated hydrogeological approach Summary and Conclusions

3. Earth Sciences Sector Groundwater Mapping 3 MODELLING So what do we mean?  Modelling is a very broad term; we have: Geological Models Conceptual Models Hydrogeological models Mathematical models Analytical models Numerical models Deterministic models Stochastic models …

4. Earth Sciences Sector Groundwater Mapping 4 Geology Mapping-Groundwater Modelling Links Groundwater investigations depend on the process of developing a conceptual flow model as a precursor to developing a mathematical model … leading to the development of a numerical approximation model Assumptions made in the development of the conceptual model depend heavily on the geological framework (or model) defining the aquifer Thus, the link between geological mapping and groundwater Modelling is the building of a conceptual model

5. Earth Sciences Sector Groundwater Mapping 5 Geology Mapping-Groundwater Modelling Links Conceptual Model Geologist Hydrogeologist Geological survey Hydrogeological model

6. Earth Sciences Sector Groundwater Mapping 6 Define Objective Conceptual Model Mathematical Model Numerical Formulation Computer Program Analytical Solution Model design Calibration Verification Prediction Presentation of results Postaudit Code verified? no yes Code Solution Field data Comparison with Field Data Pre- Processing Modelling/ Simulation Post- Processing Overview of the Hydrogeological Modelling Process Geological model

7. Earth Sciences Sector Groundwater Mapping 7 Approaches to Groundwater Modelling The flow of GW through fractured rock aquifers is modelled using one of two types of conceptual models:  Equivalent Porous Medium (EPM) If the length scale of interest is large compared with the scale of heterogeneities, such as fracture lengths  Discrete Fractured Network (DFN) When the structure of the rock is highly heterogeneous on the scale of interest The structure of the rock is described in terms of statistics of the fracture sets, i.e., fracture density and orientation

8. Earth Sciences Sector Groundwater Mapping 8 Approaches to Groundwater Modelling

9. Earth Sciences Sector Groundwater Mapping 9 Approaches to Groundwater Modelling Types of approaches, models Equivalent Porous Medium (EPM) Discrete Fractured Network (DFN) A combination of the two (Serco, 2000)

10. Earth Sciences Sector Groundwater Mapping 10 Example of Methodology for Developing Conceptual and numerical models (Rivera et al., 2001) G G GHgHg Hg Hg G, Hg G G G Hg Hg Hg G

11. Earth Sciences Sector Groundwater Mapping 11 Examples of Models developed by the GSC Aquifer StudyTypeDimensionsApproachHydrogeological Model (HM) Does a Geological model (GM) exist? Piedmont, Quebec (1998-2001) Porous medium2-D, GW flowPorousMODFLOWNo GM Gulf Islands, British Columbia (2003-2006) Bedrock, fractured rock2-D, GW flowEPM, structural geology MODFLOWYes, conceptual, not coupled Mirabel, Quebec (1999-2003) Bedrock, fractured medium 3-DEPMFEFLOW (Nastev et al, 2005) Yes, goCAD, but not coupled, built after HM (Ross et al, 2005) Oak Ridges Moraine, Ontario (1999-2003) Porous3-D, GW flowPorousMODFLOWYes, very detailed but not coupled Carboniferous Basin, New Brunswick (2000-2003) Bedrock, fractured medium 3-D GW flowEPMMODFLOWNo GM Winnipeg aquifer, Manitoba (1999-2003) Bedrock, fractured medium 3-D, GW flow and transport EPM3DFRACV (Kennedy, 2003) GM only, not conceptual GM Annapolis, Nova Scotia (2003-2006) Combined porous- fractured media 3-D GW flowEPMFEFLOWNo GM Châteauguay, Quebec (2003-2006) Bedrock, fractured rock3-D GW flowEPMFEFLOW (Lavigne, 2006) Yes, but not coupled, built after HM St.-Mathieu Esker, Quebec (2003-2006) Porous3-D, GW flowPorousMODFLOW (Riverin et al, 2005) Yes, SVM, but built after HG (Smirnoff et al, in press) Okanagan, British Columbia (2003-2009) Combined porous- fractured media 3-D, GW flowEPMPlannedPartially, only the surficial aquifer (planned) Paskapoo, Alberta (2003-2009) Bedrock, fractured rock3-D, GW flowCombined EPM/DFN (planned) Planned

12. Earth Sciences Sector Groundwater Mapping 12 Groundwater Analysis & Simulations Types Two different “schools” of groundwater scientists developing the science of hydrogeology: –fundamental hydrogeologists, and –environmental hydrogeologists. Fundamental hydrogeologists study and develop laws and methods to quantify groundwater flow from a theoretical perspective. Environmental hydrogeologists use those laws and methods to study real aquifer systems, that is, geological formations containing and conducting water. The second group is the one that most closely interacts with geologists

13. Earth Sciences Sector Groundwater Mapping 13 Types of Environmental (water) models CategoryCurrent stateApplication Separated models  Meteorological  Hydrological  Hydrogeological  High uncertainties  Mid uncertainties  Climate predictions  Surface water resources  Groundwater resources and contaminant transport Coupled models  Meteorological- hydrological  Hydrological- hydrogeological  High uncertainties  Mid uncertainties  Watershed analysis and IWRM  IWRM and CC Semi-integrated models  Hydrodynamic  Watershed dynamics  Watershed management On-going research still many uncertainties  Resource management  Watershed without groundwater, and without management  Watershed with groundwater, without management Fully-integrated models  Coupled meteorological- hydrological- hydrogeological Category of the future, still containing high uncertaintiesFor climate change scenarios coupling climate, surface water and groundwater (i.e., HydroGeoSphere, Therrien, et al., 2004)

14. Earth Sciences Sector Groundwater Mapping 14 Towards an integrated hydrogeological approach

15. Earth Sciences Sector Groundwater Mapping 15 Towards an integrated hydrogeological approach Pre-processors include information from GIS (MAPINFO) and are used to facilitate data synthesis, analysis, and visualization Simulators abound in the second phase, but the link with pre-procesors is still lacking to a large degree. Graphical User Interfaces (GUI) have become a necessity in this phase. The third phase, post-processing, has become perhaps the most important part of the modelling process, i.e., –Strong need for understanding GW from water managers and public, thus visualization is a key element in modelling. –In the future we should be able to virtually “walk” the client through and inside the simulated aquifer Future: integration of disciplines and processes

16. Earth Sciences Sector Groundwater Mapping 16 Differences and Issues HM have a very different ontology as compared to geological HM have a very different ontology as compared to geological models! models! Model Boundary conditions: Dirichlet (specified h or c); Neumann (specified c- or q-gradients); Cauchy (combined) Medium conditions: Heterogeneity, Isotropy, Anisotrophy Porous media, Fractured Media, discrete, EPM, Hybrid 1D, 2D, 3D Set of parameters: Hydraulic, Transport, Mechanic, Heat: P, H, C, T, K, S s, σ, N α, qi, t Type of modelling: Deterministic, stochastic Coupling: Hydro-transport (solute transfer); Thermohaline (flow, solute, heat); Hydro-mechanic (subsidence)

17. Earth Sciences Sector Groundwater Mapping 17 SUMMARY If the geological model is wrong, the conceptual model could be wrong and the HG model will not be successful HG ModelTo build a HG Model, you need: − A numerical code to solve for a set of equations − Discretization of space (FDM, FEM) and time − Boundary conditions − Initial conditions − Set of model parameters, per node, per element or per layer − Set of data of the stresses in the system (pumping) − Set of data for calibration (heads, conc., subsidence) We should distinguish: Geological model -- ► Conceptual model -- ► Hydrogeological model

18. Earth Sciences Sector Groundwater Mapping 18 SUMMARY all levelsThus, geologists and hydrogeologists need to enhance cooperation at all levels: − Geologists need to learn to listen to hydrogeologists − Hydrogeologists need to ask geologists and learn form their input/insight

19. Earth Sciences Sector Groundwater Mapping 19 CONCLUSIONS Increased emphasis in geological mapping and groundwater applications is observed in interrelated disciplines of Earth sciences A clear link between geological mappers and groundwater modelers is still lacking More serious efforts of communication are needed in three interrelated disciplines: geology, hydrogeology and geomatics when dealing with GW models Technology and tools abound but the three domains do not take full advantage to benefit each other

20. Earth Sciences Sector Groundwater Mapping 20 CONCLUSIONS Most important issues: differences between practitioners, e.g., HM have a very different ontology as compared to GM Integrated and automated platforms for modelling 3D processes in hydrogeology using experts systems and standard ontologies are the future and should be pursued in close cooperation between the three domains