ELISCOMB_4MBAT_GEO.TIF: Color Shaded-Relief GeoTIFF Image Showing the Combined 4-m Multibeam and LIDAR Bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Surveys H11224, H11225, H11250, H11251, H11252, H11361, H11441, H11442, H11445, H11446, H11997, H11999, H12012, and

The USGS, in cooperation with NOAA and the Connecticut DEP, is producing detailed maps of the seafloor in Long Island Sound. 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 (primarily of 2-m resolution), verified with bottom sampling and photography, and used to produce interpretations of seabed geology and hydrodynamic processes. Although each of the 18 completed surveys, ranging in area from 12 to 293 square kilometers, 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 12 multibeam and 2 LIDAR (Light Detection and Ranging) contiguous bathymetric DTMs into one dataset that covers much of eastern Long Island Sound. The new dataset is adjusted to mean lower low water, is provided in UTM Zone 18 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 exposed bedrock outcrops, 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. Anthropogenic artifacts visible in the bathymetric data include a dredged channel, shipwrecks, dredge spoils, mooring anchors, prop-scour depressions, buried cables, and bridge footings. 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 in this major east-coast estuary.

美国地质调查局（USGS）与美国国家海洋和大气管理局（NOAA）、康涅狄格州环境保护部（Connecticut DEP）合作，正在开展长岛湾海底详细制图工作。本合作研究项目的当前阶段，聚焦于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。作为该项目的组成部分，研究团队将美国国家海洋和大气管理局水文海图绘制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（分辨率多为2米），并通过海底采样与摄影开展验证工作，以此生成海底地质与水动力过程的解译成果。已完成的18项勘测项目的面积介于12至293平方千米之间，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具广度的地理视野。例如，单份勘测数据在规划与建设跨湾基础设施（如电缆、管道），或是测试区域环流模型时，其适用性存在局限。为满足此类需求，项目团队将12幅多波束测深数据与2幅激光雷达（Light Detection and Ranging, LIDAR）连续水深数字地形模型整合为一套数据集，覆盖了长岛湾的大部分东部海域。新数据集已校准至平均低低潮水位，采用UTM 18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特征与过程解译的需求，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，同时预留了未来扩展的空间。网格数据中可见的自然地貌包括裸露基岩露头、淹没冰碛物的砾石滞留沉积、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。水深数据中可见的人为扰动遗迹包括疏浚航道、沉船、疏浚弃土、系泊锚具、螺旋桨冲刷洼地、掩埋电缆以及桥梁桥墩。整合后的数据集相较于此前的资料，展现了更为完整连续的海底地形格局，为这座东海岸主要河口的科研与资源管理活动提供了基础性支撑框架。