The use of geological and hydrogeological models in environmental studies

Many duties of the Environment Agency involve a thorough understanding of water and its movement through the geosphere. The Agency has identified the development of conceptual models as the primary building blocks for their management of the water environment. Where appropriate these conceptual models provide the basis for numerical models for simulation and forecasting. Geological models play a key role in the development of the conceptual understanding and models in relation to groundwater systems under the CAMS process and the Water Framework Directive. Geological models are also useful to communicate sub-surface conditions and investigate site-specific problems in a variety of other Agency activities. By its very nature, the geometry and properties of the geosphere remain hidden from the observer and can therefore only be approximated using observations such as boreholes, surface outcrop and proxy measurements of its properties such as geophysical conductivity. In most cases the available data are not sufficient to create a data driven geological model and geologists with understanding of geological processes and the evolution of a particular area are required to complete the jigsaw puzzle of hard facts and conception to create an explicit understanding of the subsurface arrangement of rocks – the validated geological model. In recent years great advances in technology and geological-hydrogeological modelling mean that affordable models can now be produced across all of England and Wales. It is now also recognised that there are clear benefits in basing conceptual and numerical (groundwater flow) models on digital 3D geological models not only because of the formalisation of the geological interpretation but also because of the clarity of vision and understanding the 3D geological model provides. The British Geological Survey is the nation’s statutory body for the understanding of Britain’s geology. In this unique role it manages considerable data holdings including borehole logs, well data, seismic sections, geophysical datasets and digital geological linework. These datasets are the building blocks for 3D geological models. Amongst national geological survey organisations BGS has pioneered the development of 3D geological models, modelling software and the application of models. BGS is fully committed through its new strategy document (2009) to transforming its’ standard geoscience information delivery from 2D geological map outputs to 3- 4D geological and process models. This scoping study summarises the present methodologies and softwares used in the construction of geological and hydrogeological models both at BGS and elsewhere. It makes key recommendations for the closer integration of the varied styles of models, together with improvements in data formats, exchange mechanisms and enhanced collaboration between the Agency, consultants and BGS towards delivery of the business mission of the Agency.