Scottish Road Network Landslides Study - University of Glasgow

3.2.1 Hazard Factors
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INFORMATION SOURCES
Hazard factors are those conditions from the past (e.g. geology), present (e.g. slope angle) and
future (e.g. forecast rainfall) which determine either individually or in combination with other
factors the potential for a debris flow event to occur, and thus the existence of that type of
hazard.
Many hazard factors were identified at the Project Workshop and these are divided into a
number of categories. These are developed further in Sections 5 and 6.3, but for the moment
are listed with no attempt to relate factors to each other, to eliminate repetition, omission or,
indeed, to ensure that each factor resides in the correct category.
1. Geological:
a) Superficial and underlying
conditions.
b) Structural control (e.g. bedding
and dip).
c) Drift location and thickness.
d) Grading.
e) Rockhead profile.
f) Weathering.
g) Permeability.
h) Cohesion.
i) Grain size.
j) Pore pressure.
k) Soil properties.
l) Scale.
m) Glacial history.
n) Soil properties.
o) Moisture content.
2. Geomorphic:
a) Slope angle.
b) Slope aspect.
c) Slope height.
d) Instability features.
e) Paleo-landforms.
f) Stream issues.
g) Hydrological.
h) Breaks in slope.
i) Proximity of toe to
carriageway.
j) Rock outcrops.
k) Natural barriers.
3. Geotechnical:
a) Pore water pressure.
b) Saturation point.
c) Ground water table.
d) Sheer strength parameters.
e) Relative density.
f) Void ratio.
g) Rock weathering
characteristics.
h) Erodibility.
i) Maximum particle size.
4. Hydrological:
a) Channel width and depth.
b) Roughness.
c) Sinuosity.
d) Catchment area.
e) Runoff coefficients.
f) Culvert alignment, shape and
capacity.
g) Channel location.
h) Side slope stability.
i) Displacement of culvert
relative to stream.
j) Catchment infiltration.
k) Catchment drainage.
5. Vegetation:
a) Afforestation.
b) Peat.
c) Scarring.
d) Ground coverage.
e) Type.
f) Deforestation.
6. Land Use:
a) Agriculture.
b) Forestry.
c) Communities.
d) Infrastructure.
e) Utilities.
f) Sensitive developments.
g) Forestry roads.