Interpretation of Bottom Features from National Oceanic and Atmospheric Administration (NOAA) Surveys H12009, h12010, H12011, H12015, H12033, H12137, and H12139 and U.S. Geological Survey (USGS) Cruise 2011-006-FA in Block Island Sound (BISOUND_INTERP.SHP, 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. 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，正在开展新英格兰南部近海海底的精细化成图工作。本合作研究项目的当前阶段，旨在剖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所生成的数字地形模型（Digital Terrain Models, DTMs）转换为ESRI栅格网格与影像成果，通过海底采样与摄影开展验证工作，并以此开展海底地质与水动力过程的解译研究。
尽管7项具备连续覆盖范围的已完成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地理广度的视角。例如，在跨布洛克岛湾（Block Island Sound）的基础设施（如电缆、管道）规划建设，或是区域环流模型测试等场景中，单项勘测的效用存在明显局限。为满足此类需求，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覆盖布洛克岛湾大部分区域的数据集。
该全新数据集经校正至平均低潮水位，提供UTM 19区NAD83与地理WGS84两种投影格式，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精度要求，又足够精细以支持标准地理信息系统（Geographic Information System, GIS）程序的查询与操作，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反映振荡潮流强度的冰碛漂砾沉积、沙波场与冲刷洼地。底形不对称性可用于推断沉积物的净输运方向。
相较于此前可获取的资料，整合后的数据集展现了更为广阔且连续的水深地形全貌，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。本次解译成果基于多波束测深仪数据与用于验证的地面实测数据完成。
如需了解地面实测勘测的更多详情，请访问：http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-006-FA