Sediment retention in rangeland riparian buffers
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Authors: P. B. Hook
Date: 2003
Journal: Journal of Environmental Quality
Volume: 32
Number: 3
Pages: 1130-1137
Summary of Methods: The influences of buffer width and slope, vegetation characteristics, and stubble height on sediment retention were examined at the Montana Agricultural Experiment Station’s Red Bluff Research Ranch in Southwestern Montana (45˚ 35’ N, 111˚ 40’ W). Four upland (bunchgrasses), five transitional (dominated by Baltic rush with some grasses), and four wetland (Northwest Territory sedge and other sedges) paired plots were established. Two clipping treatments (2-3 cm stubble-severe and 10-15 cm-moderate) and six runoff sediment simulations (silt at 6 m, fine sand at 6m, silt at 2m, fine sand at 2m, silt at 1m and fine sand at 1m) were tested. Water and sediment were released at a set distance above the bottom of the plot and allowed to flow through the plot. These simulations occurred during June- August 1999. Clipping was done immediately before runoff simulation. Runoff samples were taken immediately after addition of sediment and then again between 15 seconds and 5 minutes until simulations were complete. Slope, runoff and sediment retention were analyzed with vegetation type, clipping treatment and buffer width.
Article Summary / Main Points: As buffer width increased, the amount of sediment collected in the runoff at the bottom of the buffer plot decreased. Slope, stubble height, and runoff rate did not have any effect on sediment retention. Sparsely vegetated buffers that are less than 2m wide on moderately steep slopes delivered a higher rate of sediment to the stream than densely vegetated buffers. Sediment delivery to streams increased if buffers strips have narrower widths, steep slopes, and sparse vegetation. When buffer width increased to 6m there was no difference between the vegetation types. Biomass, cover, or density are more appropriate vegetation characteristics than stubble height for judging capacity to remove sediment from overland runoff.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 63A Northern Rolling Pierre Shale Plains
Agrovoc Control Words: Riparian zones Rangelands Nonpoint pollution
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: runoff, slope, buffer width, stubble height, biomass, ground cover, sediment retention
Annotation: The results from this study provide vital information on what factors affect the performance of rangeland riparian buffers and are applicable to all rangeland riparian buffers. These findings will assist land managers in making recommendations on rangeland riparian buffers to minimize sediment (non-point source) pollution.
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