Southern Puerto Rico National Hydrography Dataset HUC12 Boundary

Adapted from Seaber, P.R., Kapinos, F.P., and Knapp, G.L., 1987, Hydrologic Unit Maps: U.S. Geological Survey Water-Supply Paper 2294, 63 p. Updated information not from this source is enclosed in square brackets below. A copy of USGS Water-Supply Paper 2294 may be ordered from USGS Information Services

The United States is divided and sub-divided into successively smaller hydrologic units which are classified into four levels: regions, sub-regions, accounting units, and cataloging units. The hydrologic units are arranged or nested within each other, from the largest geographic area (regions) to the smallest geographic area (cataloging units). Each hydrologic unit is identified by a unique hydrologic unit code (HUC) consisting of two to eight digits based on the four levels of classification in the hydrologic unit system.

本数据集改编自Seaber, P.R., Kapinos, F.P., 及Knapp, G.L.于1987年发表的《水文单元图：美国地质调查局水资源论文2294号，63页》。[以下更新信息非源自该来源]。欲获取美国地质调查局水资源论文2294号的副本，可从美国地质调查局信息服务处订购。美国领土被划分为一系列依次递减的水文单元，这些单元被划分为四个级别：区域、次区域、核算单元和编目单元。水文单元按照从最大地理区域（区域）到最小地理区域（编目单元）的顺序进行排列或嵌套。每个水文单元通过一个独特的由两位至八位数字组成的（水文单元代码HUC）进行标识，该代码基于水文单元系统的四个分类级别。]