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Journal of Environmental Quality Abstract - Landscape and Watershed Processes

Identifying Riparian Sinks for Watershed Nitrate using Soil Surveys


This article in JEQ

  1. Vol. 30 No. 5, p. 1596-1604
    Received: Dec 18, 2000

    * Corresponding author(s): agold@uri.edu
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  1. A. E. Rosenblatta,
  2. A. J. Gold *a,
  3. M. H. Stolta,
  4. P. M. Groffmanb and
  5. D. Q. Kellogga
  1. a Dep. of Natural Resources Science, 210B Woodward Hall, Univ. of Rhode Island, Kingston, RI 02881
    b Institute of Ecosystem Studies, Box AB, Millbrook, NY 12545


The capacity of riparian zones to serve as critical control locations for watershed nitrogen flux varies with site characteristics. Without a means to stratify riparian zones into different levels of ground water nitrate removal capacity, this variability will confound spatially explicit source–sink models of watershed nitrate flux and limit efforts to target riparian restoration and management. We examined the capability of SSURGO (1:15840 Soil Survey Geographic database) map classifications (slope class, geomorphology, and/or hydric soil designation) to identify riparian sites with high capacity for ground water nitrate removal. The study focused on 100 randomly selected riparian locations in a variety of forested and glaciated settings within Rhode Island. Geomorphic settings included till, outwash, and organic/alluvial deposits. We defined riparian zones with “high ground water nitrate removal capacity” as field sites possessing both >10 m of hydric soil width and an absence of ground water surface seeps. SSURGO classification based on a combination of geomorphology and hydric soil status created two functionally distinct sets of riparian sites. More than 75% of riparian sites classified by SSURGO as organic/alluvium–hydric or as outwash–hydric had field attributes that suggest a high capacity for ground water nitrate removal. In contrast, >85% of all till sites and nonhydric outwash sites had field characteristics that minimize the capacity for ground water nitrate removal. Comparing the STATSGO and SSURGO databases for a 64000-ha watershed, STATSGO grossly under-represented critical riparian features. We conclude that the SSURGO database can provide modelers and managers with important insights into riparian zone nitrogen removal potential.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:1596–1604.