THE USE OF MULTIPLE TECHNIQUES FOR CONCEPTUALISATION OF LOWLAND KARST, A CASE STUDY FROM COUNTY ROSCOMMON, IRELAND
Caoimhe HICKEY - (39/2,2010)
This paper summarises research carried out in county Roscommon, Ireland to characterise the workings of low-lying karst, of which little is known. The research employed a combination of five main investigative techniques, in conjunction: geomorphological mapping, spring chemistry and discharge analyses, dye-tracing, microgravity geophysical investigations and bedrock core drilling. The results enabled the production of a detailed conceptual model for the area. Surface and subsurface karst landform mapping revealed a high level of karstification. Clustering and alignment of recharge landforms is found to be a significant aspect of the karst. Analyses of spring chemistry and discharge data revealed characteristics of the aquifer systems in operation. It was found that a significant percentage of flow is via enlarged conduits but that the smaller fractures are important for providing base flow. Water tracing experiments proved that water moved from highly karstified, elevated recharge zones to springs at the periphery. Microgravity geophysical investigations, detected and located solutionally enlarged voids in the bedrock and demonstrated the importance of the shallow epikarst system as well as a deeper conduit network. Bedrock core drilling detailed the nature of the bedrock underneath karst landforms and showed the successes and failings of the geophysical investigations. Spring catchment boundaries were then delineated using water balance equations and a combination of the information retrieved from the other methods. Using these results in combination large amounts of information were gathered leading to the production of the first conceptual model for the karst of Roscommon, which can be adapted and applied to Irish Lowlands in general. The use of multiple, complimentary, investigative techniques in conjunction greatly enhanced the accuracy and success of this project. The aim of this paper, therefore is to highlight the benefits of using many analytical techniques together.