Text Files of the DGPS Navigation Logged with HYPACK Software on U.S. Geological Survey (USGS) Cruise 2011-006-FA from June 13 to June 21, 2011

The USGS, in cooperation with NOAA, is producing detailed maps of the seafloor off southern New England. The current phase of this cooperative research program is directed toward analyzing how bathymetric relief relates to the distribution of sedimentary environments and benthic communities. As part of this program, digital terrain models (DTMs) from bathymetry collected as part of NOAA's hydrographic charting activities are converted into ESRI raster grids and imagery, verified with bottom sampling and photography, and used to produce interpretations of seabed geology and hydrodynamic processes. Although each of the 7 continuous-coverage, completed surveys individually provides important benthic environmental information, many applications require a geographically broader perspective. For example, the usefulness of individual surveys is limited for the planning and construction of cross-Sound infrastructure, such as cables and pipelines, or for the testing of regional circulation models. To address this need, we integrated the 7 contiguous multibeam bathymetric DTMs into one dataset that covers much of Block Island Sound. The new dataset is adjusted to mean lower low water, is provided in UTM Zone 19 NAD83 and geographic WGS84 projections, and is gridded to 4-m resolution. This resolution is adequate for seafloor-feature and process interpretation, but small enough to be queried and manipulated with standard GIS programs and to allow for future growth. Natural features visible in the grid include boulder lag deposits of submerged moraines, sand-wave fields, and scour depressions that reflect the strength of the oscillating tidal currents. Bedform asymmetry allows interpretations of net sediment transport. Together the merged data reveal a larger, more continuous perspective of bathymetric topography than previously available, providing a fundamental framework for research and resource management activities off this portion of the Rhode Island coast. For more information on the ground-truth surveys see http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-006-FA美国地质调查局（USGS）与国家海洋和大气管理局（NOAA）合作，正编制新英格兰南部近海的详细海底地形图。当前该合作研究项目的阶段目标，是解析水深地形起伏与沉积环境分布、底栖生物群落之间的关联机制。作为该项目的组成部分，研究人员将NOAA水文海图测绘活动中采集的水深数据生成的数字地形模型（DTMs），转换为ESRI栅格网格与影像数据；经海底采样与摄影验证后，该数据被用于解读海底地质与水动力过程。尽管7项连续覆盖且已完成的单项勘测均可提供重要的底栖环境信息，但诸多应用场景需要更广阔的地理视野。例如，在跨湾基础设施（如电缆与管道）的规划建设，或是区域环流模型测试中，单项勘测的应用效能较为受限。为满足这一需求，研究团队将7块连续覆盖的多波束水深数字地形模型整合为一套数据集，覆盖布洛克岛湾的大部分区域。该新数据集已校正至平均低低潮面，采用通用横轴墨卡托投影19带NAD83（UTM Zone 19 NAD83）与世界大地坐标系1984（WGS84）两种投影方式，网格分辨率为4米。该分辨率既能满足海底地貌与过程解读的需求，又可适配标准地理信息系统（GIS）程序的查询与操作，同时为后续拓展预留了空间。网格中可见的自然地貌包括：淹没冰碛物的巨砾滞后沉积、沙波场，以及反映振荡潮流强度的冲刷洼地。底形不对称性可用于推断沉积物的净输运方向。相较于此前已有的数据成果，整合后的数据集展现出更广阔、更连续的水深地形视野，为罗德岛海岸该区域的科研与资源管理活动提供了基础框架。如需了解实地勘测的更多细节，请访问：http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-006-FA