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Agricultural Conservation Planning Framework: 2. Classification of Riparian Buffer Design Types with Application to Assess and Map Stream Corridors

Tomer, M. D., Boomer, K. M. B., Porter, S. A., Gelder, B. K., James, D. E., McLellan, E.
Journal of environmental quality 2015 v.44 no.3 pp. 768-779
buffers, classification, digital elevation models, ecosystem services, groundwater, landforms, lidar, planning, pollution load, riparian areas, riparian buffers, runoff, sediments, streambank stability, streams, vegetation, water table, watersheds, Illinois, Iowa
A watershed’s riparian corridor presents opportunities to stabilize streambanks, intercept runoff, and influence shallow groundwater with riparian buffers. This paper presents a system to classify these riparian opportunities and apply it towards riparian management planning in HUC12 watersheds. High resolution (3-m grid) digital elevation models derived from LiDAR (Light Detection And Ranging) data are analyzed to identify spatial distributions of surface runoff contributions and shallow water tables in a watershed’s riparian zones. Results are tabulated and a cross classification is applied to convey recommendations for buffer vegetation and width. Classes of buffers include those primarily placed to: 1) trap runoff and sediment; 2) influence shallow groundwater; 3) address both runoff and shallow groundwater, and; 4) maintain/improve stream bank stability. This system was applied to two headwater watersheds from each of three landform regions found in Iowa and Illinois. Riparian buffers that could intercept runoff and/or stabilize streambanks would occupy about 2.5% of the total areas of these watersheds, but intercept runoff contributions from 81-94% of the watersheds. However, the distributions of riparian zones where shallow water tables (SWT) were >25 m wide varied according to landform region. Nevertheless, these riparian zones with a wide SWT area were the most common riparian setting in all six watersheds, and found to occupy 23-53% of stream bank lengths among the six watersheds. The wide SWT setting provides opportunities to reduce nutrient loads carried via groundwater, and could be managed for a variety of ecosystem services. This riparian classification and mapping system should provide a consistent basis for developing riparian corridor plans and identifying management priorities in Midwestern headwater catchments where high resolution elevation data are available.