Mean High Water Shorelines for the Outer Cape of Massachusetts from Nauset Inlet to Race Point (1998-2005)

This data release contains mean high water (MHW) shorelines for the Outer Cape of Cape Cod, Massachusetts, from Nauset Inlet to Race Point. From 1998-2005, the U.S. Geological Survey surveyed 45 kilometers of coastline 111 times using a ground-based system called Surveying Wide-Area Shorelines (SWASH). The SWASH system used a six-wheeled amphibious all-terrain vehicle as a platform for an array of Global Positioning System sensors. High-accuracy measurements of horizontal position, vertical position, and beach slope were collected at 0.5-second intervals as the vehicle traversed a single, shore-parallel line along the foreshore. The data were interpolated onto a coast-following reference line at 2-meter intervals. The shoreline position (defined as the intersection of the MHW datum with the foreshore) was determined by extrapolating from the location of the vehicle-driven track to the location of the MHW contour. The uncertainty for each shoreline point was calculated and the shoreline data were written to netCDF and ASCII csv files. This SWASH dataset represents a unique time series for quantifying large-scale coastal evolution, seasonal shoreline variability, and coastal behavior due to storms.

本次发布的数据包含美国马萨诸塞州科德角外海岬（从诺塞特湾到雷斯角）的平均高潮位（mean high water, MHW）岸线数据。1998年至2005年间，美国地质调查局（U.S. Geological Survey）使用名为广域岸线测量系统（Surveying Wide-Area Shorelines, SWASH）的地面测量系统，对45千米长的海岸线开展了111次勘测。该SWASH系统以六轮两栖全地形车作为搭载阵列式全球定位系统（Global Positioning System, GPS）传感器的平台。当车辆沿前滩行驶一条与岸线平行的单行轨迹时，系统以0.5秒的间隔采集高精度的水平位置、垂直位置以及海滩坡度数据。随后将数据以2米的间隔插值到沿岸线延伸的参考线上。岸线位置（定义为平均高潮位基准面与前滩的交点）通过将车辆行驶轨迹的位置外推至平均高潮位等值线的位置来确定。研究人员计算了每个岸线点的不确定性，并将岸线数据存储为netCDF与ASCII CSV格式文件。该SWASH数据集为量化大规模海岸演化、季节性岸线变化以及风暴引发的海岸动力过程提供了独特的时间序列数据。