Anfuso Giorgio, Bowman Dan, Danese Chiara, Pranzini Enzo
Departamento de Ciencias de la Terra, Facultad de Cuiencias del Mar y Ambientales, Universitad de Cádiz, Poligono Rìo San Pedro s/n, 11510, Puerto Real, Càdiz, Spain.
Department of Geography, Ben-Gurion University of the Negev, P.O. Box 653, 84105, Beer Sheva, Israel.
Environ Monit Assess. 2016 Oct;188(10):568. doi: 10.1007/s10661-016-5571-1. Epub 2016 Sep 16.
Field surveys, aerial photographs, and satellite images are the most commonly employed sources of data to analyze shoreline position, which are further compared by area based analysis (ABA) or transect based analysis (TBA) methods. The former is performed by computing the mean shoreline displacement for the identified coastal segments, i.e., dividing the beach area variation by the segment length; the latter is based on the measurement of the distance between each shoreline at set points along transects. The present study compares, by means of GIS tools, the ABA and TBA methods by computing shoreline displacements recorded on two stretches of the Tuscany coast (Italy): the beaches of Punta Ala, a linear coast without shore protection structures, and the one at Follonica, which is irregular due to the presence of groins and detached breakwaters. Surveys were carried out using a differential global positioning system (DGPS) in RTK mode. For each site, a 4800-m-long coastal segment was analyzed and divided into ninety-six 50-m-long sectors for which changes were computed using both the ABA and TBA methods. Sectors were progressively joined to have a length of 100, 200, 400, and 800 m to examine how this influenced results. ABA and TBA results are highly correlated for transect distance and sector length up to 100 m at both investigated locations. If longer transects are considered, the two methods still produce good correlated data on the smooth shoreline (i.e. at Punta Ala), but correlation became significantly lower on the irregular shoreline (i.e., at Follonica).
实地调查、航空照片和卫星图像是分析海岸线位置最常用的数据来源，这些数据通过基于面积分析（ABA）或基于断面分析（TBA）的方法进行进一步比较。前者通过计算已识别海岸段的平均海岸线位移来执行，即通过将海滩面积变化除以段长度；后者基于测量沿断面的设定点处各条海岸线之间的距离。本研究借助地理信息系统工具，通过计算意大利托斯卡纳海岸两段记录的海岸线位移，比较了ABA和TBA方法：线性海岸且无海岸保护结构的蓬塔阿拉海滩，以及因存在丁坝和离岸防波堤而不规则的福洛尼卡海滩。使用实时动态（RTK）模式下的差分全球定位系统（DGPS）进行测量。对于每个地点，分析了一段4800米长的海岸段，并将其划分为96个50米长的扇区，使用ABA和TBA方法计算这些扇区的变化。扇区逐步合并，长度分别为100米、200米、400米和800米，以研究这对结果有何影响。在两个调查地点，对于长达100米的断面距离和扇区长度，ABA和TBA结果高度相关。如果考虑更长的断面，这两种方法在平滑海岸线上（即蓬塔阿拉）仍能产生相关性良好的数据，但在不规则海岸线上（即福洛尼卡）相关性显著降低。
