The causes of erosion

The causes of feature erosion

Shrinking beaches

As with soil compaction, erosion of a feature is also caused by exertion of pressure. However, the greatest erosional forces exerted on a feature come from natural sources such as rain, wind and, in the intertidal area, wave action. At a site level, these forms of erosion will be much more significant than that caused by recreation. However, as recreational activities tend to be concentrated along specific access routes or in small areas, their impact can be magnified, causing significant erosional patches within a site or feature. Such erosion is particularly evident in coastal areas frequented by walkers and in the vicinity of heavily used access points.

The rate of erosion is not simply dependent upon the intensity of activities in the vicinity of a feature. It is also related to the erodibility of the soil, which in turn is linked to its texture, its capacity to absorb and filter water and its organic and chemical content. Figure 6.1 illustrates this relationship.

1.    Wind                                                                         1. Types of activity

2.    Rain                                                                          2. Location of activity

3.    Waves                                                                       3. Level of activity

                              NATURAL IMMUNITY OF FEATURE

                                1. Texture

                                2. Infiltration capacity

                                3. Chemical/biological content

                                EROSION OF FEATURE

UK CEED (1998)

Soft coastal habitats tend to face the greatest risk of erosion from both natural processes and also human activities, including recreation. Recreation may have a particular erosional impact on sand dunes and sand flats. Table 6.2 summarises the main causes of erosion on marine features.

UK CEED (1998)

ü Significant recreational impact ü Small recreational impact

r Little or no recreational impact

Many of the UK’s shorelines, consisting of soft rock expanses, mud and sand flats, are undergoing a process of ‘retreat’, whereby the sea is eroding the intertidal features in front of static sea defences. Such shrinking is largely a result of a number of natural processes, including wave and wind actions and sea level rise. However, these processes can be accentuated by erosional pressures caused by recreational activities.

The decrease in the width of sandy beaches, which is common throughout Europe, can have a serious effect upon the ability of the habitat to support indigenous species. It can also have a significant impact upon its amenity value for tourism and recreation. It can also have the knock-on effect of putting greater recreational pressure on other similar sites. The impact on tourist incomes could have important indirect effects on the environment as less money may be available for management and nature conservation purposes.

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