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Hillslope sediment fence catch efficiencies and particle sorting for post-fire rain storms

Author(s): Codie Wilson, Stephanie Kampf, Joseph W. Wagenbrenner, Lee H. MacDonald, Hunter Gleason
Year Published: 2021
Description:

Hillslope erosion has often been monitored with sediment fences, but these can underestimate sediment yields due to overtopping of runoff and associated sediment. We modified four sediment fences to collect and measure the runoff and sediment that overtopped the fence in addition to the sediment deposited behind the fence. Specific objectives were to: (1) determine the catch efficiency of sediment fences measuring post‐fire hillslope erosion; (2) assess particle sorting of sand, silt/clay and organic matter from each hillslope through the sediment fence and subsequent runoff collection barrels; (3) evaluate how catch efficiency and particle size sorting relate to site and rainfall‐runoff event characteristics; and (4) use runoff simulations to estimate sediment fence volumes for future post‐fire monitoring.

 

Catch efficiency ranged from 28‐100% for events and 38‐94% per site for the entire sampling season, indicating a relatively large underestimation of sediment yields by sediment fences. Most of the eroded sediment had similar proportions of sand and silt/clay as the hillslope soils, but the sediment behind the fence was significantly enriched in sand while the sediment that overtopped the fence was more strongly enriched in silt/clay. The sediment fences had capacities of 3 m3 for hillslopes of 0.19‐0.43 ha, but simulations of runoff for 2‐ to 100‐yr storms indicate that the sediment fences would need a capacity of up to 240 m3 to store all of the runoff and associated sediment. More accurate measurements of sediment yields with sediment fences require either increasing the storage capacity of the sediment fence(s) to accommodate the expected volume of runoff and sediment, reducing the size of the contributing area, or directly measuring the runoff and sediment that overtop the fence.

Citation: Wilson, Codie; Kampf, Stephanie; Wagenbrenner, Joseph W.; MacDonald, Lee H.; Gleason, Hunter. 2021. Hillslope sediment fence catch efficiencies and particle sorting for post-fire rain storms. Earth Surface Processes and Landforms 46(1):267-279. https://doi.org/10.1002/esp.5021
Topic(s): Fire Behavior, Weather, Fire Effects, Ecological - Second Order, Soils, Water, Post-fire Management, Post-fire Rehabilitation, Erosion Control, Recovery after fire, Restoration
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
Hot Topic(s):
NRFSN number: 22625
FRAMES RCS number: 62203
Record updated: Feb 3, 2021