Subsurface Flow and Erosion Induce Streambank Failure.
(A05-wilson937700-poster)
Authors:
G.V. Wilson* - USDA-ARS National Sedimentation Laboratory S.M. Dabney - USDA-ARS National Sedimentation Laboratory F.D. Shields - USDA-ARS National Sedimentation Laboratory
Abstract:
Field observations have shown that up to 85% of the sediment leaving a watershed may be from streambank failure. Subsurface flow contributes significantly to streamflow generation but its
contribution to streambank failure is not well known. Flow through unconsolidated, permeable layers results in erosion of the material at the face of streambank leaving the bank undercut and susceptible to failure. The objective of this study was to quantify the soil physical properties and hydrologic conditions associated with subsurface flow and erosion that results in streambank failure. Subsurface flow and erosion was quantified using lateral flow collection pans placed against exposed faces of the Little Topashaw Creek streambank. Numerous streambank locations were identified in which a highly permeable, unconsolidated sand layer occurred above a water-restricting clay horizon. Pans were permanently installed at one location at five depths in duplicate for a total of 10 pans. Water collected by the 100 cm long pans was routed to sealed containers where the volume of flow was recorded and sediment sampled. Alternatively, subsurface flows were measured at several seep locations following selected events by temporarily installing 50 cm long flow-collection pans. The physical properties of soil profiles that exhibited subsurface flow-induced erosion were characterized. These data will be used to model the subsurface flow-surface flow interaction.
Speaker Information: Glenn Wilson, USDA-ARS National Sedimentation Laboratory, USDA-ARS NSL 598 McElroy Dr, Oxford, MS 38655; Phone: 662-232-2927; E-mail: [email protected]
Session Information: Tuesday, November 4, 2003, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 205)
Keywords: Subsurface flow; bank failure; erosion; sediment
