Hesp Patrick A, Hernández-Calvento Luis, Hernández-Cordero Antonio I, Gallego-Fernández Juan B, Romero Levi García, Miot da Silva Graziela, Ruz Marie-Helene
Beach and Dune Systems (BEADS) Laboratory, College of Science and Engineering, Flinders University, South Australia 5042, Australia.
Grupo de Geografía Física y Medio Ambiente, Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, Unidad Asociada ULPGC-CSIC, CTM Taliarte, 35214 Telde, Las Palmas, Spain.
Sci Total Environ. 2021 Jun 15;773:144815. doi: 10.1016/j.scitotenv.2020.144815. Epub 2021 Feb 3.
This study examines the role of sediment supply in controlling the formation and the spatial patterns of nebkha, numbers and sizes, present in foredunes fronting coastal dunefields of the arid northwest African and the Canary Islands coasts. Sediment supply is estimated qualitatively and quantitatively by various measures, and the number and size of nebkhas are obtained on a range of beach-dune systems. In the case of the Canary Islands, LiDAR data and orthophotos with high spatial resolution (0.25 m) are used to measure sediment supply/activity, nebkha numbers and sizes, and vegetation variables, whereas data availability is less on the African coast. Results show that sediment supply exerts a major control on nebkha development such that as sediment supply increases, the number of coastal nebkha decreases, and the size of individual plants/nebkha increases. Once sediment supply is large, nebkha can only form on the immediate backshore if space is available, and a point is reached when the sediment supply is so large that nebkha do not, or cannot form. The data presented here provide two indicators which could be applicable to other dune systems. Firstly, by estimating the number of nebkha and the vegetation cover, the degree of aeolian sedimentary activity or sediment supply might be estimated. Secondly, the type of aeolian landform present provides a qualitative indication of sediment supply and aeolian activity.
本研究考察了沉积物供应在控制非洲西北部干旱地区和加那利群岛海岸前沙丘上存在的藤本植物沙丘的形成及空间格局、数量和大小方面所起的作用。通过各种方法对沉积物供应进行了定性和定量估计，并在一系列海滩-沙丘系统上获取了藤本植物沙丘的数量和大小。对于加那利群岛，利用激光雷达数据和高空间分辨率（0.25米）的正射影像来测量沉积物供应/活动、藤本植物沙丘的数量和大小以及植被变量，而非洲海岸的数据可得性较低。结果表明，沉积物供应对藤本植物沙丘的发育起主要控制作用，即随着沉积物供应增加，海岸藤本植物沙丘的数量减少，单个植物/藤本植物沙丘的大小增加。一旦沉积物供应量大，如果有空间，藤本植物沙丘只能在紧邻的后滨形成，当沉积物供应量大到一定程度时，藤本植物沙丘就不会或无法形成。本文所呈现的数据提供了两个可应用于其他沙丘系统的指标。首先，通过估计藤本植物沙丘的数量和植被覆盖度，可以估计风成沉积活动或沉积物供应的程度。其次，现存风成地貌的类型提供了沉积物供应和风成活动的定性指示。
