TY - JOUR

T1 - Sediment supply to beaches

T2 - cross-shore sand transport on the lower shoreface

AU - Aagaard, Troels

PY - 2014/4

Y1 - 2014/4

N2 - Many beaches have been built by an onshore supply of sand from the shoreface, and future long-term coastal evolution critically depends on cross-shore sediment exchange between the upper and the lower shorefaces. Even so, cross-shore sediment supply remains poorly known in quantitative terms and this reduces confidence in predictions of long-term shoreline change. In this paper, field measurements of suspended sediment load and cross-shore transport on the lower shoreface are used to derive a model for sediment supply from the lower to the upper shoreface at large spatial and temporal scales. Data collection took place at five different field sites that exhibit a wide range of wave conditions and sediment characteristics. Data analysis shows that both suspended sediment load and cross-shore sediment transport scale with the grain-related mobility number which ranged up to ψ ≈ 1000 in the measurements while the effect of orbital velocity skewness is more limited. A 1 year long simulation of sediment transfers between the lower and the upper shorefaces on a natural beach compares well with transport rates estimated from long-term bar migration patterns and aeolian accretion on the same beach.

AB - Many beaches have been built by an onshore supply of sand from the shoreface, and future long-term coastal evolution critically depends on cross-shore sediment exchange between the upper and the lower shorefaces. Even so, cross-shore sediment supply remains poorly known in quantitative terms and this reduces confidence in predictions of long-term shoreline change. In this paper, field measurements of suspended sediment load and cross-shore transport on the lower shoreface are used to derive a model for sediment supply from the lower to the upper shoreface at large spatial and temporal scales. Data collection took place at five different field sites that exhibit a wide range of wave conditions and sediment characteristics. Data analysis shows that both suspended sediment load and cross-shore sediment transport scale with the grain-related mobility number which ranged up to ψ ≈ 1000 in the measurements while the effect of orbital velocity skewness is more limited. A 1 year long simulation of sediment transfers between the lower and the upper shorefaces on a natural beach compares well with transport rates estimated from long-term bar migration patterns and aeolian accretion on the same beach.

U2 - 10.1002/2013JF003041

DO - 10.1002/2013JF003041

M3 - Journal article

VL - 119

SP - 913

EP - 926

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 0148-0227

IS - 4

ER -