Methods to prioritize placement of riparian buffers for improved water quality |
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Authors: | Mark D Tomer Michael G Dosskey Michael R Burkart David E James Matthew J Helmers Dean E Eisenhauer |
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Institution: | (1) USDA/ARS National Soil Tilth Laboratory, 2110 University Blvd., Ames, IA 50011, USA;(2) USDA/FS National Agroforestry Center, Lincoln, NE, USA;(3) Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA;(4) Department of Biological Systems Engineering, University of Nebraska, Lincoln, NE, USA |
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Abstract: | Agroforestry buffers in riparian zones can improve stream water quality, provided they intercept and remove contaminants from
surface runoff and/or shallow groundwater. Soils, topography, surficial geology, and hydrology determine the capability of
forest buffers to intercept and treat these flows. This paper describes two landscape analysis techniques for identifying
and mapping locations where agroforestry buffers can effectively improve water quality. One technique employs soil survey
information to rank soil map units for how effectively a buffer, when sited on them, would trap sediment from adjacent cropped
fields. Results allow soil map units to be compared for relative effectiveness of buffers for improving water quality and,
thereby, to prioritize locations for buffer establishment. A second technique uses topographic and streamflow information
to help identify locations where buffers are most likely to intercept water moving towards streams. For example, the topographic
wetness index, an indicator of potential soil saturation on given terrain, identifies where buffers can readily intercept
surface runoff and/or shallow groundwater flows. Maps based on this index can be useful for site-specific buffer placement
at farm and small-watershed scales. A case study utilizing this technique shows that riparian forests likely have the greatest
potential to improve water quality along first-order streams, rather than larger streams. The two methods are complementary
and could be combined, pending the outcome of future research. Both approaches also use data that are publicly available in
the US. The information can guide projects and programs at scales ranging from farm-scale planning to regional policy implementation. |
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Keywords: | Conservation planning Conservation practices Non-point pollution Soil survey Terrain analyses |
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