ARS | Publication request: Seepage Erosion Properties Contributing to Streambank Failure [abstract]

Submitted to: Agronomy Abstracts
Publication Type: Abstract
Publication Acceptance Date: August 28, 2004
Publication Date: October 29, 2004
Citation: Wilson, G.V., Periketi, R., Fox, G.A., Cullum, R.F. 2004. Seepage erosion properties contributing to streambank failure [abstract]. Agronomy Abstracts #3343.

Technical Abstract: Field observations have suggested that up to 85% of the sediment leaving a watershed may be from streambank failure. Numerous streambank locations were identified on the Little Topashaw Creek in the Yalobusha River Watershed in which an unconsolidated sand layer above a clay layer exhibited seepage erosion. The objective of this study was to quantify the impact of hydraulic head and slope of the restricting layer on seepage erosion and the resulting streambank failure. Lysimeter experiments were conducted in which the hydraulic head and slope of the water-restricting layer were varied for three replicated streambank depths. Lysimeters were saturated then allowed to drain for 24 h to achieve consistent antecedent conditions near field-capacity for each flow experiment. The dynamics of bank undercutting due to seepage erosion from the subsurface flow layer were quantified while simultaneously measuring the dynamics of water pressure in the soil profile. Seepage erosion was observed to begin within 3 minutes of head establishment. Sediment concentrations greater than 1 kg/L were observed resulting in sufficient undercutting of the bank to result in bank failure within minutes of flow initiation for deep streambanks (80 cm) and less than 1 hour for shallow (30cm) streambanks.