Comparison of digital elevation models for aquatic data development

Thirty-meter digital elevation models (DEMs) produced by the U.S. Geological Survey (USGS) are widely available and commonly used in analyzing aquatic systems. However, these DEMs are of relatively coarse resolution, were inconsistently produced (i.e.; Level 1 versus Level 2 DEMs), and lack drainage enforcement. Such issues may hamper efforts to accurately model streams, delineate hydrologic units (HUs), and classify slope. Thus,. the Coastal Landscape Analysis and Modeling Study (CLAMS) compared streams, HUs, and slope classes genera erated from sample 10-meter drain age-enforced (DE) DEMs and 30-meter DEMs. We found that (1) drainage enforcement improved the spatial accuracy of streams and HU boundaries more than did increasing resolution from 30 meters to 10 meters, particularly in flatter terrain; (2) streams and HU boundaries were generally more accurate when delineated with Level 2 than with Level 1 30-meter DEMs; and (3) the 10-meter DE-DEMs better represented both higher and lower slope classes. These findings prompted us to have 10-meter DE-DEMs produced for the Coast Range Province of Oregon, increased confidence in CLAMs outputs from the 10-meter DE-DEMs, and should benefit others interested in using DEMs far aquatic analyses.