Groundwater Contamination: Use of Models in Decision-Making, 1989 Proceedings of the International Conference on Groundwater Contamination: Use of Models in Decision-Making, Amsterdam, The Netherlands, 26–29 October 1987, Organized by the International Ground Water Modeling Center (IGWMC), Indianapolis — Delft

The protection of groundwater resources has emerged in recent years as a high priority topic on the agenda of many countries. In responding to the growing concern over deteriorating groundwater quality, many countries are developing a comprehensive regulatory framework for the management of subsurface water resources with management referring to both quantity and quality aspects. Within this framework, groundwater models are rapidly coming to playa central role in the development of protection and rehabilitation strategies. These models provide forecasts of the future state of the groundwater aquifer systems and/or the unsaturated zone in response to proposed management initiatives. For example, models will predict the effects of implementing a proposed management scheme on water levels and on the transport and fate of pollutants. The models are now used in the formulation of policies and regulations, the issuing of permits, design of monitoring and data collection systems, and the development of enforcement actions. The growth in the use of these sophisticated tools has led to many unforeseen problems in groundwater management. Lingering issues include reliability of codes, quality assurance in model development and applications, efficient utiliza­ tion of human and material resources, technology transfer and training. Some issues have legal ramifications, as in cases where the applications of models have been contested in courts.

Contributions.- Opening and Introduction.- Opening address.- Model application in the field of soil and groundwater quality: a policy point of view.- to the conference theme.- International Standpoints.- Groundwater quality management: a multi-dimensional problem.- Report on the seminar ’Modelling for Water Management’, organized by the European Institute for Water in Como, Italy, May 21 and 22, 1987.- Topic 1: Risk Assessment and Management.- Invited paper.- The consideration of risk and uncertainty in the management of groundwater contamination.- Specialist papers.- A method to assess the risk and admissibility of one or more activities in the inflow area of a receptor.- An expert system for groundwater risk assessment.- Environmental risk assessment using stochastic modelling.- Topic 2: Models in Regulation and Legislation.- Invited paper.- Methodology for developing a national water policy with Israel’s case as an example.- Specialist papers.- Modelling aspects of an environmental impact statement for a coastal area: a case study.- Topic 3: Quality Assurance in Modelling.- Invited paper.- The role of the International Ground Water Modeling Center (IGWMC) in groundwater modeling.- Specialist papers.- Testing, verification, and validation of two-dimensional solute transport models.- Imprecision in groundwater modelling and management.- Topic 4: Parameter Estimation and Stochastic Modelling.- Invited paper.- Parameter estimation in groundwater modelling: from theory to application.- Specialist papers.- Analysis of data from well tests in dikes and fractures.- Stochastic optimal management of perched saline aquifers in irrigated regions.- The outlier problem and an on-line procedure to detect outliers in groundwater quality time series.- Are reconstructors useful in groundwater protection decision-making?.- Indirect evaluation of hydrogeologic spatial correlation length: an approach to quantification of hydraulic conductivity variance reduction using synthetic hydraulic tests.- A moment method for calculating groundwater flow uncertainty: the analysis of a landfill.- Topic 5: Modelling Heat and Contaminant Transport.- Invited paper.- On the finite element integration of the dispersion-convection equation.- Specialist papers.- Application of GEOTHER/VT4 to assess groundwater transients in a high level radioactive waste repository.- STROP: a computer program simulating flow patterns and pollution migration in saturated groundwater.- On the modelling of groundwater flow under the influence of salinity.- Models of nitrate transport at different space and time scales for groundwater quality management.- Upwind preconditioned conjugate gradients for finite element transport models.- Modelling immiscible organic chemical transport in soils and groundwater.- Calculation of three-dimensional groundwater transport using second-order moments.- The use of a hydrology contaminant transport model for the prediction of the effect of air stripping on the in situ cleaning of contaminated soil.- Environmental impacts of aquifer thermal energy storage (ATES): modelling of the transport of energy and contaminants from the store.- Topic 6: Geo-Chemical and Bio-Chemical Modelling.- Specialist papers.- Solute transport in the unsaturated zone: model verification and input data.- Model of petroleum mineralization response to soil aeration to aid in site-specific in situ biological remediation.- The environmental impact of agriculture on surface and groundwater quality and the use of Nitsol/Phosol in decision-making.- Recent developments in coupling geochemical and hydrologic processes.- MISS: a coupled model of water chemistry and hydrodispersive transport in aquifers.- The utility of one- and two-dimensional coupled geochemical and geohydrological migration codes.- Use of models and soil survey information in assessing regional water quality.- Topic 7: Modelling of Fractured Rock Aquifers.- Invited paper.- The use of stochastic concepts in modelling fracture flow.- Specialist papers.- The fractured rock model approach to modelling natural geological pollution barrier systems involving organic soils.- A study of the validity of flow predictions in discrete fracture networks, generated from field data statistics.- Regional modelling of fractured rock aquifers.- Topic 8: Regional Groundwater Contamination Studies.- Specialist papers.- The prediction of contamination potential in coastal aquifers from proposed shallow disposal sites for low-level radioactive wastes.- Development and applications of three-dimensional analytic element models for transport modelling.- Application of a flow and transport model to the exploration and management of partially polluted aquifers.- Groundwater contamination due to surface disposal of geothermal wastewater at Nesjavellir, Iceland.- Flow pattern modelling around a well extraction scheme in the vicinity of the River Rhine in the Netherlands.- Modelling time-variant groundwater quality in a catchment area influenced by agriculture and river infiltration.- FLOSA: a tool for regional three-dimensional flow systems analysis.- Topic 9: Solid and Hazardous Waste Management Studies.- Invited paper.- Use of groundwater models and the settlement process at the Chem-Dyne hazardous waste site.- Specialist papers.- Groundwater contamination by soil disinfection.- Groundwater models as part of the safety assessment of underground disposal of hazardous waste in the Netherlands.- Finite element method to assess the impact on groundwater quality of trace metals released from a coal fly ash repository.- REFCON: a ground- and surface water pollution response model for the design and optimalization of clean-up and soil protection strategies for petrochemical complexes.- Solute transport modelling of organic compounds in groundwater west of the Lawrence Livermore National Laboratory, Livermore, California.- Study of groundwater pollution around waste disposal sites with a simulation model.- Hydrogeological studies within the framework of an ecological risk analysis of harbour mud deposits.- Panel 1: The Role of Data in Modelling.- The role of data in modelling.- The role of data in the management of groundwater.- Panel 2: Models in Regulation.- Models in regulation: a report on the panel discussions.