DESIGNING A SPATIALLY BALANCED, RANDOMIZED SITE SELECTION PROCESS FOR REGIONAL STREAM SURVEYS: THE EMAP MID-ATLANTIC PILOT STUDY

摘要

In 1993, the U.S. Environmental Protection Agency(EPA),as part of the Environmental Monitoring and Assessment Program(EMAP), initiated a sample survey of streams in the mid-Atlantic. A major objective of the survey was to quantify ecological condition in wadeable streams across the region. To accomplish this goal, we selected 615 stream sites using a randomized sampling design with some restriction. The design utilized the digitised stream network taken from 1:100,000-scale USGS topographic maps as the sample frame.