Cross-shore ripple variations under laboratory partially standing waves : a possible clue to paleo-wavelength

Abstract

Setting the experimental condition under partially standing wave, which little attention has been given to in spite of being found in nature, a series of wave-flume experiments of development of ripples were performed, using four kinds of sand with different diameters (0.15 mm≤D≤1.23 mm). Ripples developed under partially standing waves showed the cross-shore variations in ripple spacing, asymmetry and crest-line pattern, depending on the positions to ‘nodes’ and ‘anti-nodes’, and on grain size. Ripple spacing was the largest under nodes and the smallest under anti-nodes and was associated with the variation in the orbital diameter. Ripples with rounded crests and bifurcated crest-lines tended to form under anti-nodes.