Footpath degradation of the Malvern Hills - Malvern Hills Conservators

Stephen Britnell
Footpath degradation of the Malvern Hills
Erosion increases with the increase in slope angle, and slope length. This is due to
the increase in velocity and volume of surface runoff, and the erosive power of walkers is
greater going up hill. Also on a slope rainsplash is greater in the downslope direction than
upslope, and so increases transportation of particles (Morgan 1995). The relationship
between erosion and slope can be expressed by the equation (see Figure 1.) by Zingg
(1940).
Vegetation acts as a protective layer between the atmosphere and the soil. Above
ground components, such as leaves and stems, absorb some energy of falling raindrops.
Below ground components, comprising root systems contribute to the mechanical strength of
the soil (Sharma et al. 1989). Plant cover provides resistance from recreational pressure and
dissipates the energy of running water and so reduces the erosive power of overland flow.
However this is only true for dense uniform vegetation cover. Clumps of vegetation are less
effective and may lead to concentrations of flow with localised high velocities. (Morgan 1995)
1.4 Weathering
Weathering as well as erosion contributes to the degradation of upland regions.
Weathering occurs over a longer period of time than erosion, and the effects may not be
noticed for hundreds of years, however the weathering of rocks causes them to become
awkward to walk upon, and so contributes to the problem of footpath divergence and
widening.
“Weathering is the breakdown and alteration of materials near the earth’s surface to
products that are more in equilibrium with newly imposed physio-chemical conditions.” Ollier
(1984)
Physical weathering is the breakdown of material by entirely mechanical methods
brought about by a variety of causes. The main processes at work are frost weathering, salt
weathering, insulation, moisture swelling, slaking, and abrasion. Frost weathering is the most
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