Abstract
Analyzing the Relationship of Events in a Hydrography Network Track: Water Resources Author(s): Jeff Simley Analyzing the relationship of events in a hydrography network can lead to important conclusions regarding cause and effect in the landscape. The hydrography of the United States is defined by the National Hydrography Dataset (NHD), which maps surface water, links it to a flow network, and provides an addressing system to position events within the network. With network position and flow established, it is possible to use operators to determine relationships in terms of route, sequence, distance, time, and value. For example, it is possible to find diversions upstream of a streamgage, look at the trend in sequenced pH values, determine the distance between water sampling sites, calculate the time of travel between a chemical spill and a drinking water intake, or find all species downstream of a construction site. This can be done using simple tools applied to the NHD in Geodatabase within the ArcMap environment. Jeff Simley U.S. Geological Survey Geography PO Box 25046, MS-507, DFC Denver , CO 80225 US Phone: 303-202-4131 E-mail: jdsimley@usgs.gov |
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