Abstract
Automating Stream Selection: Global Map Hydro from NHD Track: Water Resources Author(s): Robin Gary, Zachary Wilson The Global Mapping project is an international effort to develop and integrate 1:1,000,000-scale (1:1M) geospatial data to facilitate environmental research at spatial scales ranging from continental to global. The 1:100,000-scale National Hydrography Dataset (NHD) is the base being used to create the U.S. 1:1M Global Map drainage dataset. After appropriate headwater reaches are identified, a downstream trace algorithm attributes streams for inclusion in the 1:1M dataset. The downstream trace algorithm is written in VBA, using ArcObjects, and implemented as an easy-to-use tool within the ArcMap environment. The tool considers flow direction, number of adjacent downstream reaches, stream names, and feature type to extract preliminary 1:1M flow paths from NHD. Existing similar-scale data indicate that the selection algorithm creates a 1:1M dataset with appropriate density and preserves hydrologic significance. Automation of the selection process reduces human bias, increases repeatability, and facilitates feature-level documentation. Robin Gary U.S. Geological Survey 8027 Exchange Drive Austin , TX 78754 US Phone: 512-927-3512 E-mail: rhgary@usgs.gov Zachary Wilson U.S. Geological Survey 8027 Exchange Dr. Austin , TX 78754 US Phone: 512-927-3511 E-mail: zdwilson@usgs.gov |
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