Sediment transport is a key element in intertidal beach morphodynamics, but measurements of sediment transport are often unreliable. The aim of this study is to quantify and investigate cross-shore sediment transport and the resulting topographic changes for a tide-dominated, sandy beach. Two fortnight-long field experiments were carried out during which hydrodynamics and sediment dynamics were measured with optical and acoustic sensors, while the beach topography was surveyed with a permanent terrestrial laser scanner. Suspended sediment was generally well-mixed and currents were largest at approximately 1.5 m above the bed, which resulted in a peak in sediment transport at 1/3 of the high tide level. The mean transport direction was onshore during calm conditions (wave height <0.6 m) thanks to tidal currents and offshore during energetic conditions due to undertow. Oscillatory transport was always onshore because of wave asymmetry but it was subordinate to mean transport. The intertidal zone showed an alternation of erosion and accretion with formation of morphological features during energetic (no storm) conditionsand smoothening of the morphology during calm conditions. A good qualitative and quantitative agreement was found between the daily cross-shore suspended load and beach volume changes, especially during calm conditions.

No abstract

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

No abstract

The intertidal beach is very dynamic and is characterized by high sediment transport rates which may result in large topographic changes. Measuring techniques are well developed for both sediment transport and beach topography but the quantification of transport remains difficult. This paper provides an in-depth review of studies that cross-checked sediment transport measured underwater to transport derived from topographic change and/or predictive formulas to optimize future measuring campaigns in the intertidal zone. Based on these studies it is strongly recommended to measure sediment transport at multiple locations in the intertidal zone, although it is recognized that this is costly. When the suspended sediment is mixed and vertically stratified, it should be gauged over the entire water column. Acoustic backscatter intensity can be used for this purpose but needs to be corrected for grain size and turbulence. When cross-checking measured sediment transport rates with beach volume changes topographic profiles may not be sufficient. Instead, laser scanning of the beach is recommended. Additionally, valuable insights can be obtained from continuously measuring the beach topography. When beach topography is only measured during low tide, wind-driven transport should be taken into account during energetic conditions. It is deemed necessary to improve sensors to measure bed load transport and suspended sediment transport close to the bed and to further improve formulas to predict sediment transport. With the suggestions given in this paper it is encouraged to perform field investigations of sediment transport in the intertidal zone to improve our knowledge of the intertidal beach morphodynamics.