Submitted to: American Water Resources Association Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2003
Publication Date: May 15, 2003
Citation: BURKART, M.R., JAMES, D.E., TOMER, M.D. ESTIMATING HYDROLOGIC VARIABLES AND TERRAIN FEATURES TO STRATEGICALLY LOCATE RIPARIAN BUFFERS. AMERICAN WATER RESOURCES ASSOCIATION CONFERENCE PROCEEDINGS. 2003. CD-ROM. MIDDLEBURG, VA. Technical Abstract: Methods for estimating and mapping hydrologic variables that influence the optimum location of vegetated riparian buffers are proposed using examples from the deep loess region of the Midwest. Digital elevation data and stream-flow records were used to define four hydrologic variables; a wetness index, a baseflow index, a sediment transport index, and a discharge index. Stream initiation points were established in all headwaters using direct observations and a threshold model based on primary topographic attributes. The spatial distribution of the four indices is presented in the context of stream orders. Groundwater dominates transport through riparian areas in the region producing substantial opportunities to manage nitrate, most pesticides, and some pathogens with riparian buffers. A discharge index combined with a baseflow index demonstrates that buffers along first order streams have more than an order of magnitude greater opportunity to affect dissolved contaminants than similar reaches of larger streams. A wetness index showed that surface soils are more likely to become saturated along smaller streams enhancing the potential for these sites to retain sediment, nutrients, and remove many pesticides from runoff. Riparian areas with small wetness index values represent unstable bank conditions where slopes are great unless catchment areas are small. Most hydrologic indicators of potential vegetated buffer function do not significantly vary among stream orders. However, a discharge index shows that riparian buffers along first order streams can intercept a much larger fraction of both runoff and groundwater than those occupying a similar reach along larger streams.