QSC graphs: an aid to classification of data-poor aquifers in Ireland
G. R. Wright, 2000. "QSC graphs: an aid to classification of data-poor aquifers in Ireland", Groundwater in the Celtic Regions: Studies in Hard Rock and Quaternary Hydrogeology, N. S. Robins, B. D. R. Misstear
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The Geological Survey of Ireland’s aquifer classification system recognizes three main categories: Regionally Important, Locally Important and Poor Aquifers. This system is increasingly used to assist local authorities and state agencies to make decisions on planning applications and integrated pollution control licences, by prioritizing areas according to the value of their underlying groundwater resources. Most aquifers in Ireland are unconfined fractured hard rock aquifers, often of limited extent, which can exhibit a wide range of properties. Pumping test data are scarce, patchy and often of uncertain quality, and reliable transmissivity or permeability values are unavailable for many aquifers. Under these circumstances, the classification of a given geological formation in a given region can be difficult. The ‘QSC Graph’ compares the specific capacity (SC) for a borehole, determined by a pumping test, with the abstraction rate during the test (Q), and indicates a ‘borehole productivity index’, in five classes (I, II, III, IV and V from highest to lowest). From the relative frequency of productivity classes for a given aquifer, the appropriate aquifer category can be inferred. However, other types of information for the aquifer should also be considered. The current QSC data set comprises about 1100 boreholes, and for individual formations up to 150 boreholes. The minimum data set required for an aquifer, depending on the diversity or compactness of the data, is between 20 and 50. Examples are given of the application of the approach to a number of Irish aquifers.
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Groundwater in the Celtic Regions: Studies in Hard Rock and Quaternary Hydrogeology
This book covers a diverse range of hydrogeological environments that occur in the Celtic regions of Britain and Ireland. These include hard rock aquifers of Lower Palaeozoic and Precambrian age, generally dominated by fracture flow within a shallow zone of weathering; Carboniferous Limestone aquifers, often characterized by conduit flows in karstic systems; dual-porosity Permo-Triassic sandstone aquifers; and Quaternary deposits, many of which form shallow granular aquifers. The papers presented here address a number of current issues common to the Celtic regions, including: groundwater protection policies, groundwater management in karst aquifers, groundwater development in Quaternary aquifers, groundwater evaluation in data-scarce aquifers and groundwater supplies to small island communities.