2. TECHNICAL AND GEOLOGICAL ASPECTS OF COASTAL EROSION: IMPACT ANALYSIS ON BIODIVERSITY AND HUMAN POPULATION Erosion affects more than 70% of the coasts worldwide and is caused by human activities and natural environment changes, making the coastal sediment dynamics lose balance and lead to coastline retreat and beach erosion. Coastal land is being swallowed by the seawater and coastal villages and houses are forced to move inland: so humans living spaces are squeezed, the beach biodiversity and ecological balance are been destroyed, and there are direct or indirect harms on human life and natural environment. Nowadays, coastal erosion has changed from a natural environmental change to a serious hazard.
2.1. NATURAL CAUSES OF EROSION Erosion, in principle, is the detachment
events such as glaciation or orogenic
and transportation of the weathered rock
cycles that may greatly alter sea levels
materials away from a coast. There are
and tectonic activities that cause coastal
four types of erosion that take place at
land subsidence or emergence. Most
coastal regions: (a) abrasion - the force
coastlines are naturally dynamic, and
of sand and pebbles being thrown by the
cycles of erosion are often an important
sea scraping away at rock, (b) attrition
feature of their ecological character.
- the wearing away of rocks in the sea
Excluding the impact of human activity,
by hitting off one another, (c) hydraulic
these processes are simply natural
action - the wearing away of rocks by the
evolutionary phenomena. The occurrence
force of the water, this can also occur
of coastal erosion is dependent upon
through the compression of air in small
the balance between the resistance,
gaps by water, (d) solution - the chemical
or erodibility, of the coastline and the
breakdown of rock by seawater. Rocks
strength, or erosivity, of the waves and
can also be broken down by physical and
tides affecting the area. These conditions
chemical weathering processes.
are, in turn, reliant upon a number of factors, including: topography, the
Natural shoreline changes induced by
composition and structure of the exposed
erosion and accretion take place over
geological formations, local currents and
a range of time scales. They may occur
tidal range, wave climate (wave height,
in response to short-term events, such
period, direction and fetch), groundwater,
as storms, regular wave action, tides
sediment supply (provided by eroding
and winds, or in response to long-term
cliffs and rivers’ load), and relative sea
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