SEABOSS Images from Block Island Sound Collected During U.S. Geological Survey (USGS) Cruise 2011-006-FA in JPEG Format

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.Interpretations were derived from the multibeam echo-sounder data and the ground-truth data used to verify them.
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）与美国国家海洋和大气管理局（NOAA）合作，正开展新英格兰南部近海海底的详细制图工作。本合作研究项目的当前研究阶段，旨在分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。作为该项目的一部分，研究人员将NOAA水文测绘活动中采集的水深数据所生成的数字地形模型（DTMs）转换为ESRI栅格网格与影像产品，通过底质采样与水下摄影开展验证，并用于海底地质与水动力过程的解译工作。
尽管7项已完成的连续覆盖调查单就每项而言均可提供关键的底栖环境信息，但多数应用场景需要覆盖范围更广的地理视角。例如，单独的调查数据在规划与建设跨湾口基础设施（如海底电缆、管道）或开展区域环流模型测试时，实用性较为受限。为满足这一需求，研究团队将7块连续的多波束测深数字地形模型整合为覆盖布洛克岛海峡大部分区域的统一数据集。
该新数据集已校准至平均低低潮水位，提供通用横轴墨卡托投影19带NAD83与世界大地测量系统1984（WGS84）两种投影格式，栅格分辨率为4米。该分辨率既可满足海底地貌与过程解译的需求，又足够精细，可通过标准地理信息系统（GIS）程序进行查询与处理，同时预留了后续扩展的空间。
该栅格中可见的自然地貌包括淹没冰碛的漂砾沉积、沙波场，以及反映往复潮流强度的冲刷洼地。底形的不对称性可用于推断净输沙方向。整合后的数据集相较以往公开数据，展现了更全面、更连续的水深地形全貌，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。
本次解译结果均基于多波束测深仪数据与用于验证的实地调查数据得出。
如需了解实地验证调查的更多信息，请访问：http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-006-FA