Wetlands Characterization (MEGIS)

WETCHAR contains National Wetland Inventory polygons for towns in Maine characterized on six different wetland functions and values at a scale of 1:24000. The base layer for the Wetlands Characterization is the National Wetlands Inventory (NWI) data. In the Wetlands Characterization, wetlands are characterized for floodflow alteration, sediment retention, finfish habitat, shellfish habitat, plant and animal habitat, and cultural value. A series of queries is applied to the National Wetlands Inventory coverage. The resultant file is basically the NWI polygons with fields for the presence or absence of the characteristics within each query and fields indicating whether or not the wetland met all the criteria for each query. The process started with NWI coverage by 1:24,000 quad sheet. The quad boundaries were dissolved on NWI attribute. Open water (lakes, rivers, ponds) was removed unless identified as a "PUB" in the NWI classification. The NWI polygons were then dissolved on the system attribute of the NWI classification (P, L, E, R, M). The queries were then applied to that coverage.WETCHAR数据集包含缅因州各城镇的国家湿地清单（National Wetland Inventory）面状矢量要素，以1:24000比例尺针对6类不同湿地功能与价值开展了特征表征。本次湿地特征表征（Wetlands Characterization）的基础图层为国家湿地清单（National Wetlands Inventory，下称NWI）数据。在该特征表征过程中，湿地的评估维度涵盖洪水径流调节、沉积物滞留、有鳍鱼类栖息地、贝类栖息地、动植物栖息地及文化价值6项指标。研究团队将一系列查询分析操作应用于国家湿地清单覆盖图层，最终生成的文件基本保留了NWI面状要素的原始结构，新增两类属性字段：一类用于标识各项查询分析中对应特征的存在与否，另一类用于标注该湿地是否满足各项查询的全部判定标准。本次处理流程始于以1:24000比例尺划分的NWI覆盖图幅：首先依据NWI属性对图幅边界进行融合；随后移除所有开放水域（湖泊、河流、池塘），除非其在NWI分类体系中被标记为"PUB"类；接着依据NWI分类的系统属性（P、L、E、R、M）对NWI面状要素进行融合；最后将前述查询分析应用于该处理后的覆盖图层。