Outline the Combined 4-m Multibeam Bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Surveys H12009, H12010, H12011, H12015, H12033, H12137, and H12139 offshore in Block Island Sound (BISOUND_OUTLINE shapefile, Geographic, WGS84)

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.

美国地质调查局（USGS）与美国国家海洋和大气管理局（NOAA）合作，正在编制新英格兰南部海域的详细海底地形图。本合作研究项目的当前阶段，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。作为该项目的组成部分，研究人员将NOAA水文海图测制作业所获取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，并通过底质采样与水下摄影探测进行验证，以此开展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测量各自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角。例如，单份测量数据在规划、建设跨海峡基础设施（如电缆与海底管道），或验证区域环流模型时，其应用范围受到限制。为解决这一需求，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覆盖布洛克岛海峡大部分区域的数据集。新数据集经平均低潮面校正，采用通用横轴墨卡托投影19带NAD83坐标系与WGS84大地坐标系，网格分辨率为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）程序进行查询与操作，同时预留了后续扩容空间。网格中可见的自然地貌包括埋藏冰碛物的砾石滞留沉积、沙波场，以及反映往复潮流强度的冲刷洼地。通过底形不对称性可解译泥沙净输运方向。相较于此前的数据集，本次融合后的整体数据展现了更广阔、更连续的水深地形视角，为罗德岛沿岸该区域的科研与资源管理活动提供了基础框架。