Submitted to: The Sierran
Publication Type: Popular Publication
Publication Acceptance Date: May 10, 2002
Publication Date: June 1, 2002
Citation: Burkart, M.R., Tomer, M.D. 2002. Hydrologic constraints to the effectiveness of vegetated riparian buffers and constructed wetlands for pollution control. The Sierran. 32(2):6. Technical Abstract: Vegetated riparian buffers and constructed wetlands are among the stream-corridor management systems that can reduce the amount of sediments, nutrients, and biocides entering streams. Hydrologic factors can constrain water-quality benefits of these practices because riparian buffers can only affect the quality of water they intercept. Overland runoff only occurs during and immediately following rainfall or snow melt. Sediment, phosphorus and some biocides are transported via runoff that can be intercepted in riparian buffers. Infiltration into riparian soils can be a useful process to remove or alter soluble contaminants carried with runoff water. Soil permeability and depth to the water table will affect the quantity of water that will infiltrate and the length of time that water will reside in the subsurface. Groundwater can constitute more than 80% of annual stream flow. Contaminants that move through groundwater are likely to impact stream quality more frequently than contaminants associated with runoff. Buffers located and designed to process groundwater will have a substantial impact on stream quality, particularly nitrate and soluble biocides. Constructed wetlands are being promoted as the best alternative to enhance riparian processes for contaminant removal in agricultural areas with artificial drainage. Artificial drainage was installed in much of Iowa and the Midwest. This short-circuits natural pathways where contaminants could be removed in riparian areas. Successful implementation of any riparian management will require an understanding of hydrology. Riparian management systems also offer landowners the potential to manage for long-term sustainability through market benefits obtained from wildlife, timber, and other perennial crops.