The first phase of the ‘Groundwater 3D’ (GW3D) project was a government funded, multi-annual endeavour, focussed on assisting Geological Survey Ireland meet its policy goals in the areas of characterisation of and research into groundwater resources, within a number of specific themes. The investigation of the geometry of sand and gravel deposits throughout Ireland, as both a water resource and a flow pathway, was one of the priority themes identified for pursuance. The output of a previously collated national sand and gravel aquifer map, comprising 93 sand and gravel aquifer bodies, was variable, due to the inconsistent amounts of information available to delineate each aquifer body. ‘Full’ Quaternary stratigraphic mapping, showing the three-dimensional extent of these sand and gravel deposits, had not been completed for the majority of these areas across the country. Such mapping and subsequent characterisation was undertaken in phase I of GW3D to provide field evidence on the true nature of these deposits (i.e. thickness, saturated thickness, depth to bedrock, depth to water table, degree of grading and bedding, lateral extent and variability), in the third dimension. Thus, as well as mapping the extent and depth of the deposits, the investigations considered their hydraulic properties. A consistent, systematic approach was developed which led to the investigation of 420 discrete deposits of sand and gravels nationwide; of these approximately 200 aquifers were delineated or further characterised. Dissemination of the work is achieved through online publishing of the revised aquifer maps on the Geological Survey Ireland website with an accompanying bespoke report for each aquifer.
Geological Survey Ireland is currently moving in the direction of providing three-dimensional subsurface models, focusing on applying sound geological science to meet the requirements of end users. Phase 2 of ‘GW3D’ will be a direct progression of phase 1, focussing on further investigating of the hydraulic properties of the aquifers and developing sand and gravel aquifer models. It is envisaged these models will help to undertake and facilitate the management of resources (such as wholesome drinking water supplies) and the environment (such as applied data provision for integrated catchment management). At the commencement of phase 2 a systematic approach to the investigations has recently been developed, using geographically-distributed case studies. The detailed hydrogeological investigation of the Robertstown Sand and Gravel Aquifer in Co. Kildare is one such case study. This project will use groundwater modelling software (MODFLOW) in order to better understand the geometry of the aquifer, the water resources it holds, and the effect of groundwater abstraction on the stability of a nearby canal.