Digital Grain Size Analysis of a Mixed Sand and Gravel Beach

Abstract

Abstract PENTNEY, R.M. and DICKSON, M.E., 2012. Digital grain size analysis of a mixed sand and gravel beach. A new technique to estimate the properties of sediment from digital images is investigated. Sediment was obtained from mixed sand and gravel beaches in Hawke Bay, New Zealand. Samples were manually sieved, and grain size distributions were compared to those obtained from digital images. Digital image analysis provided variable estimates of the grain size distribution (R2 = 0.21−0.74), with much poorer estimates obtained when images contained grain sizes beyond the range of sediments imaged for the calibration catalogue. A reasonable approximation of the mean grain size of a sample was returned from digital analyses when compared with the mean grain size obtained from sieving (R2 = 0.68), provided all sediment sizes within images fitted within the calibration catalogue. This paper discusses limitations of the technique when applied to mixed sand and gravel beaches, and possibilities for overcom...