TY - JOUR
T1 - Observations of sand waves, megaripples, and hummocks in the Dutch coastal area and their relation to currents and combined flow conditions
AU - Passchier, S.
AU - Kleinhans, M. G.
PY - 2005/12/1
Y1 - 2005/12/1
N2 - [1] This paper aims to investigate the distribution and stability of large-scale bed forms in response to storm and fair-weather conditions in a shallow marine environment. Multibeam and side-scan sonar data off the Dutch coast (median grain size 0.25-0.35 mm) were collected to monitor sand waves (λ = 100-800 m) and superimposed megaripples (λ = 1-40 m) through multiple storm and fair-weather events. Box cores were used to observe the vertical bed structure and grain size. In the Dutch coastal area, two-dimensional (2-D) megaripples (X = 1-15 m) are the dominant bed forms in current-dominated (>0.4 m/s) tidal flow regimes with oscillatory flows <0.15 m/s. Effects of trapping of fine material under these conditions by tube building Lanice conchilega colonies on bed form development are suspected but need further study. At slightly higher energy conditions, 3-D megaripples (λ = 5-15 m) begin to form on the shoreface. After seasonal storms, at oscillatory flows >0.4 m/s, undulating bed topography of mound-like 3-D bed forms (λ = 20-40 m) is observed. Immediately after storms, these bed forms are covered by smaller 3-D megaripples, which are related to sets of low-angle converging laminae in box cores, interpreted as hummocky cross stratification (HCS). The sand waves form compound bed forms of sets of 2-D and 3-D megaripples. The morphology of the sand waves is a function of the general wind-wave climate of the marine environmental setting, with flat-topped 3-D sand waves occurring in shallow wave-dominated settings and 2-D sand waves occurring in the tide-dominated environment farther offshore.
AB - [1] This paper aims to investigate the distribution and stability of large-scale bed forms in response to storm and fair-weather conditions in a shallow marine environment. Multibeam and side-scan sonar data off the Dutch coast (median grain size 0.25-0.35 mm) were collected to monitor sand waves (λ = 100-800 m) and superimposed megaripples (λ = 1-40 m) through multiple storm and fair-weather events. Box cores were used to observe the vertical bed structure and grain size. In the Dutch coastal area, two-dimensional (2-D) megaripples (X = 1-15 m) are the dominant bed forms in current-dominated (>0.4 m/s) tidal flow regimes with oscillatory flows <0.15 m/s. Effects of trapping of fine material under these conditions by tube building Lanice conchilega colonies on bed form development are suspected but need further study. At slightly higher energy conditions, 3-D megaripples (λ = 5-15 m) begin to form on the shoreface. After seasonal storms, at oscillatory flows >0.4 m/s, undulating bed topography of mound-like 3-D bed forms (λ = 20-40 m) is observed. Immediately after storms, these bed forms are covered by smaller 3-D megaripples, which are related to sets of low-angle converging laminae in box cores, interpreted as hummocky cross stratification (HCS). The sand waves form compound bed forms of sets of 2-D and 3-D megaripples. The morphology of the sand waves is a function of the general wind-wave climate of the marine environmental setting, with flat-topped 3-D sand waves occurring in shallow wave-dominated settings and 2-D sand waves occurring in the tide-dominated environment farther offshore.
UR - http://www.scopus.com/inward/record.url?scp=36448958491&partnerID=8YFLogxK
U2 - 10.1029/2004JF000215
DO - 10.1029/2004JF000215
M3 - Article
AN - SCOPUS:36448958491
SN - 2169-9003
VL - 110
JO - Journal of Geophysical Research: Earth Surface
JF - Journal of Geophysical Research: Earth Surface
IS - 4
M1 - F04S15
ER -