USGS Water Resources of Michigan - Bank stability concerns-Fluvial Geomorphology-Study of the Kalamazoo River

Bank Stability Concerns

Project Chief
Cyndi Rachol

Fluvial Geomorphology - Study of the Kalamazoo River

Evaluate Historical Literature and Aerial Photography

Bank Stability Concerns

Channel Evolution and Designs

Published Report
WRIR02-4098

Table of Contents

Search ALL of USGS

Feedback

Bank Stability Concerns Unstable banks provide additional sediment to water, affecting water quality and sediment load. Areas with unstable banks are prone to channel widening. Bank stability is dependent on sediment type, bank profile, vegetation, and hydrology. Concerns are elevated due to the history of the study reach. Even small amounts of bank erosion would provide additional material for transport and facilitate the availability of contaminants to the water column. Bank stability model Developed by USDA-ARS National Sedimentation Laboratory Excel-based macros that calculate Factor of Safety for bank using values for stresses based on field measurements Inputs include bank profile, sediment characteristics, vegetative cover, and hydrograph Bank data collection Data collection focused on area between city of Plainwell and intersection of Kalamazoo River near M-89 below Otsego City Dam. Performed two field tests: jet test and bore-hole shear test (BST) Collected samples for particle size and bulk density analysis to be analyzed at USGS Kentucky Sediment Laboratory Collected photos of each transect and noted vegetation

Jet test device

Base of jet set-up
Apron along bottom must remain sealed to bank to maintain water pressure

Pressure gages and handle for jet blocking plate

Jet blocking plate and orifice

Depth gage and air bleed valve

Depth gage is slowly lowered and is used to measure the depth of scour hole

Bore hole shear test (BST)

Is performed on top of bank
Measures shear failure of sediment using resistance provided by normal stresses applied by shear head to sides of auger hole
Each unsaturated layer is tested
Test time varies depending on sediment composition

Hand pump or air tank supplies pressure to shear head
Crank mechanism with shear pressure gage sits above bore hole on platform.

Shear head expands to apply normal pressure to sides of bore hole; Once pressure is applied, sediment is allowed to consolidate-Click image for larger photograph

Shear head expands to apply normal pressure to sides of bore hole
Once pressure is applied, sediment is allowed to consolidate (~0.5 to 1 hr)

After consolidation period, a crank holding the shear head in place is turned, raising the shear head in small increments
Apparatus is connected to gage that measures the shear pressure resisting the rising shear head
Once failure begins, maximum shear pressure is noted

Sediment transport model

Using failure predictions from USDA-ARS bank stability model, will modify bank profile, toe/bed elevations, and toe/bed sediment size descriptions for transect inputs into 1D sediment transport model ("Bennett model")