Relationship Between Scour Depth and Bend Radius of Curvature on the Red River

Thorne, Colin R.; Biedenharn, David S.; Combs, Phil G.; ,

Relationship Between Scour Depth and Bend Radius of Curvature on the Red River

by Colin R. Thorne, Univ of Nottingham, United Kingdom,
David S. Biedenharn, Univ of Nottingham, United Kingdom,
Phil G. Combs, Univ of Nottingham, United Kingdom,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering

Abstract:

Studies of bank and bend processes were undertaken on the Red River between Index, Arkansas and Shreveport, Louisiana in connection with the navigation project on the river downstream of Shreveport. The aim was to establish the relationship between bend geometry and scour depth for bends with a variety of outer bank types. The results show that the banks are formed in materials of five different origins: meander belt alluvium and clay plug materials associated with the present flood plain; back swamp deposits in a terrace left from the nineteenth century flood plain; Pleistocene/Tertiary materials in the valley walls; and revetments formed from riprap. On the basis of an engineering-geomorphic analysis, a relationship between outer bank type and bend scour depth was found. Generally, scour depth increases as outer bank resistance to erosion and failure increases, especially for tight bends of low radius of curvature to width ratio. Maximum scour pool depths for revetted bends are 5 to 20% greater than those for the equivalent free, alluvial meander. These results suggest that additional bed scour should be expected in a bendway as a consequence of stabilizing the outer bank, even if the original alignment is maintained. The summary curves presented could be useful in predicting the degree of further scour which must be allowed for in the revetment design.

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