National Wetlands Inventory (Hosted Feature Layer)

The National Wetlands Inventory (NWI) from the U.S. Fish and Wildlife Service (USFWS) represents the extent, approximate location and type of wetlands, riparian, deepwater and related aquatic habitats in Massachusetts. The present goal of the Service is to provide the citizens of the United States and its Trust Territories with current geospatially referenced information on the status, extent, characteristics and functions of these data in priority areas to promote the understanding and conservation of these resources. These data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979).The National Wetlands Inventory - Version 2, Surface Waters and Wetlands Inventory was derived by retaining the wetland and deepwater polygons that compose the NWI digital wetlands spatial data layer and reintroducing any linear wetland or surface water features that were orphaned from the original NWI hard copy maps by converting them to narrow polygonal features. Additionally, the data are supplemented with hydrography data, buffered to become polygonal features, as a secondary source for any single-line stream features not mapped by the NWI and to complete segmented connections. See full metadata.美国鱼类和野生动物管理局（U.S. Fish and Wildlife Service, USFWS）的国家湿地清单（National Wetlands Inventory, NWI）记录了马萨诸塞州内湿地、河岸带、深水及相关水生栖息地的分布范围、大致位置与类型。该机构当前的目标是为美国本土及其托管领地的民众提供优先区域内这些数据的最新地理空间参考信息，涵盖相关栖息地的现状、分布范围、特征与功能，以推动对这类资源的认知与保护。这些数据按照考尔丁等人（Cowardin et al., 1979）的定义，勾勒出湿地与地表水的面积范围。国家湿地清单第二版——地表水与湿地清单的构建方式为保留组成NWI数字湿地空间数据图层的湿地与深水多边形要素，并将原始NWI纸质地图中遗漏的线性湿地或地表水要素转换为窄多边形要素后重新纳入数据集。此外，数据集还补充了经缓冲区处理转换为多边形要素的水文数据，以此作为NWI未绘制的单线溪流要素的补充数据源，并完善分段水系的连接。详见完整元数据。