Airflow dynamics and aeolian sand transport across a beach-climbing dune-clifftop dune system

This study presents an analysis of wind flow and sediment transport from the beach, up a 50m high, long (130m), steep (mean slope 26°) climbing dune and across a 1.5 m high max, 85 m long and 17.5 m wide clifftop dune 30km south of Dakhla in Morocco, NW Africa during highly oblique incident wind conditions. Multiple 2D sonic and cup/vane anemometers and sand traps were utilised for measurements. Flow steering was significant on the upper climbing dune. Flow deceleration occurred near the dune toe, and topographic forcing of flow was considerable on the upper slopes of the climbing dune. Near-surface flow steadiness (CVU1, CVU0.25) on the climbing dune straight slope segment was low and constant The distance upslope over which the airflow reached the speed comparable to that on the beach increases as the incident wind speed increases. The greatest flow acceleration and speed-up was observed at the cliff edge reaching 250% at 1m height and 220% at 0.25m height for the lowest incident wind speed class (4-5 m/s). The sand transport rate declined from the beach to the climbing dune toe and lower slope, but at the uppermost section of the climbing dune was 4 times higher than at the beach for the 7-8m/s incident wind speed. Sand in aeolian transport was generally finer than surface sand with mean grain size increasing up the slope. A comparison of the sand transport data collected with sand transport models, and the effects of slope on aeolian transport are also examined.

本研究针对非洲西北部摩洛哥达赫拉以南30公里处的沙丘系统开展风沙流与输沙过程分析，该系统包含一座高50米、长130米、平均坡度26°的爬升沙丘，以及一座最大高度1.5米、长85米、宽17.5米的崖顶沙丘，实验期间遭遇高度斜入射风况。研究采用多台二维声学风速仪（2D sonic anemometer）、旋杯/旋叶风速计（cup/vane anemometer）与集沙仪（sand trap）开展野外观测。
结果显示，爬升沙丘的上部区域存在显著的气流转向（flow steering）现象；沙丘趾部附近出现气流减速，而沙丘上坡段受到地形强迫（topographic forcing）的气流变化十分显著。在爬升沙丘的直坡段，近地表气流稳定性（CVU1、CVU0.25）较低且保持恒定。随着入射风速升高，气流达到海滩处风速所需的上坡距离随之增加。在崖顶边缘观测到最大的气流加速与增速效应：针对最低入射风速等级（4-5 m/s），1米高度处的风速增幅达250%，0.25米高度处达220%。
输沙率从海滩向沙丘趾部及下坡段逐渐降低，但在7-8 m/s入射风速条件下，爬升沙丘最上段的输沙率是海滩处的4倍。风成搬运（aeolian transport）的沙粒总体比地表沙粒更细，且沿坡向上的平均粒径逐渐增大。本研究还对比了实测输沙数据与输沙模型的结果，并探讨了坡度对风蚀输沙过程的影响。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于摩洛哥西北部一个海滩-爬坡沙丘-崖顶沙丘系统的风流动动力学和风成沙传输研究，通过现场测量分析了风加速、沙传输速率变化及沙粒粒度特征。数据集包含2023年发布的沉积学相关数据，使用CC BY-NC 4.0许可证，适用于非商业研究目的。