4-m Grid of the Combined 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_4MUTM, UTM Zone 19, NAD83)

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（United States Geological Survey, USGS）与美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）合作，正在制作新英格兰南部近海的详细海底地图。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以及底栖生物群落之间的关联。作为该项目的一部分，研究人员将美国国家海洋和大气管理局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（Digital Terrain Models, DTMs）转换为ESRI栅格网格与影像，并通过海底采样与摄影进行验证，随后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勘测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野。例如，单项勘测在规划和建设跨湾基础设施（如电缆与管道），或是测试区域环流模型时，其适用性会受到限制。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个数据集，覆盖了布洛克岛湾（Block Island Sound）的大部分区域。新数据集已校准至平均低低潮面，采用UTM 19区NAD83与WGS84地理坐标系两种投影方式，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，又足够精细，可通过标准地理信息系统（Geographic Information System, GIS）程序进行查询与处理，同时预留了未来扩展的空间。网格中可见的自然地貌包括反映振荡潮流强度的水下冰碛物漂砾沉积、沙波场以及冲刷洼地。底形不对称性可用于推断净输沙方向。整合后的数据集相较于此前的资料，展现了更广阔、更连续的水深地形视角，为罗德岛沿岸这片海域的科研与资源管理活动提供了基础性框架。