North America Watersheds

The North American Environmental Atlas – Basin Watersheds data set shows watersheds in North America at 1:10,000,000. A watershed is an area encompassing part or all of a surface drainage basin, a combination of drainage basins, or a distinct hydrologic feature. Watersheds are mapped in a hierarchical system, with the largest units encompassing the entire drainage areas of major rivers or river systems or encompassing seaboard areas. Within these large units, subsequently smaller units encompass the drainage areas of smaller rivers and streams. Watersheds are classified differently in Canada, Mexico, and the United States; the data set includes a continental classification (the North American Watershed, or NAW level), as well as the classification unique to each country. This data set was compiled from each country’s watershed file and adjustments were made to the data to resolve misalignments and mismatches across international borders. Files Download北美环境地图集——流域水系数据集以1:1000万比例尺展示了北美地区的流域水系分布。流域指涵盖部分或全部地表排水流域、多个排水流域组合，或是独立水文特征的区域。流域采用分级制图体系：最大一级单元覆盖主要河流或河系的完整汇水区，亦或是沿海区域；在此大型单元之下，次级更小的单元则覆盖小型河流与溪流的汇水区。加拿大、墨西哥与美国的流域分类标准各有不同，本数据集既包含跨大陆统一分类体系（北美流域，North American Watershed，简称NAW），也纳入了各成员国专属的分类标准。本数据集整合自各成员国的流域文件，并针对数据进行了调整，以解决跨国边界间的对齐偏差与匹配不一致问题。文件下载