Table 1. Interactions of bank erosion and failure processes and conditions

Table 1. Interactions of bank erosion and failure processes and conditions.

* Effects on bank soils

Climatic zones

(A)

(B)

(C)

(D)

(E)

(F)

(G)

Surface

soils

frost

→ 2, 5, 6, 9, 10, 1418

→ 14

Excessive soil

Heavy and/or prolonged precipitation

X

1

pore water (1)

Snowmelt

Rapid river/lake level drop

Irrigation

Ground ice melt

→ 14

Soil water piping (2)

Water flow through coarse-grained,

X

2

1

permeable soil strata discharging

along bank face

→ 2, 5, 6, 911, 14, 18

→ 14

Soil freeze-thaw (3)

Ground temperatures fluctuating

X

1

below and above 32F cause soil

pore water to freeze and thaw,

→ 14

2

and soil mass to swell and shrink

→ 2, 5, 6, 911, 14, 18

→ 14

Ground temperatures below 32F

Growth of ground ice (4)

X

1

2

and suction of soil water to freezing

→ 14

2

soil zone

→ 911, 1517 2

no effect

X

River/lake ice

Ice moving along a bank

1

scour/abrasion (5)

→ 911, 1517 2

→ 14

River/lake ice push (6)

Ice moving into or onto a bank due

X

1

3

1

to thermal expansion, wind or currents

River/lake ice

Previously grounded ice with incorpor-

no effect

X

2

3

rafting (7)

ated sediment breaks free and flows away

→ 2, 57, 911, 1318

Changes in soil grain

Normal chemical and physical weather-

X

1

→ 6, 14

mineralogy and

ing actions and reactions

1

physical condition (8)

→ 1417 2

→ 14

Water wave actions (9)

Wind

X

1

3

1

Boat passage

Landslides

Water current detach-

Gravity

no effect

X

ment and transport (10)

Thermal

2

3

Wind

Wind detachment

Wind blowing over transportable soil

no effect

X

2

3

and transport (11)

Toppled trees (12)

Loss of soil support below

X

2

root zone

→ 57, 911, 1418 2

Man and animal

Burrowing, trampling (compacting),

X

1

3

2

3

actions (13)

excavating and disrupting the surface

of bank soils

Soil failures (14)

Excessive soil water

X

2

Seismic action

Loss of bank toe support

Raindrop detachment (15)

Rain drop impacts on unvegetated

no effect

X

2

bank soils

Overland sheet flow (16)

Infiltration capacity of soil is exceeded,

no effect

X

2

3

resulting in flows on the soil surface

Rill/gully flow (17)

Flow on a sloped soil surface becomes

no effect

X

concentrated in surface depressions

2

3

often where vegetative cover is sparse

Snow sliding (18)

Binding forces between bank face sedi-

no effect

X

ments and snow become insufficient

2

to hold snow mass in place

→ 2, 57, 911, 1418 2

→ 14

Ground ice melting/

Exposure to solar radiation, water

X

1

and air temperatures above 32F

sublimation (19)

*Effects on bank soils:

→ 3, 810

1 Reduction in granular interlocking and/or soil cohesion with associated

Effect could increase the susceptibility of bank soils to other processes or condi-

1

loss of soil strength and stability

tion in column A with their associated effects in columns C and D and so on.

2 Removal of soil particles from in-situ position

3 Removal of soil particles from site

Note: This table may not include all factors.

2