Sand and gravel aggregate resource management and conservation in Northern Ireland

Abstract

Glaciofluvial landforms in Northern Ireland are important resource bodies for sand and gravel aggregate, and also form integrated geomorphic assemblages which have scenic and aesthetic importance in the landscape. Determining the overall «value» of sand and gravel features in economic and landscape terms involves making assumptions about their geotechnical properties, future extraction rates, and quantifying otherwise poorly-defined aesthetic attributes. This paper deals mainly with landscape economic, scientific and aesthetic «values» and rates of resource depletion on different spatial scales. Based on remote sensing, field mapping and automation of the data set using a geographical information system (GIS), glaciofluvial sand and gravel is calculated to cover 534 km2±10% in Northern Ireland (approximately 3·4% of land area). By assuming specific deposit thicknesses for each landform type, mappable sand and gravel reserves are calculated to range between 2400 and 14 675 million tonnes. Based on low growth, high growth and «business as usual» scenarios of future annual increases in extraction rate from 1996 AD onwards, these reserves are calculated to have a lifespan of 48–314 yr (median value 132 yr). Case studies of the Glarryford esker complex and the Lough Fea deltas complex illustrate the local landscape importance of sand and gravel features. These case studies show that defining, quantifying and evaluating landscape resources at a local-scale is a necessary part of aggregate resource management and conservation where the overall resource-base is diminishing.