WHAT IS A COAST?• The area lying between the land and the sea. It includes the shore and the cliffs• a narrow zone where the land and the sea overlap and directly interact.
WHAT IS A SHORE?• The shore is the zone between the lowest water mark and the highest water mark reached by storm waves.• The shore can be divided into three sections:1. Backshore: • Stretches landwards from the high water level. • Can be reached by high storm waves.2. Foreshore: • Lies between the low water level and the high water level. • Covered with water during high tide.3. Offshore: • Never exposed even during low tide
Wave TerminologyWAVES?• The undulations of water in the sea or oceans created by wind blowing over their surfaces.• The parts of a wave:i. Crest - the highest part of a waveii. Trough - the lowest part of a waveiii. Wave height- vertical distance between the crest and the trough Parts of the waveiv. Wave length- distance between two consecutive crests or two consecutive troughs
Wave Terminology• Wavelength (L) - the distance between two successive crests. It can be determined by the formula: L = 1.56T , 2where L= wavelength, T=wave period• Wave period (T) – is the time taken for a wave to travel through one wavelength.
Wave Terminology• Wave velocity (C) – is the speed of movement of a crest in a given period of time.• Wave steepness – the ratio of the wave height to the wave length ( H / L ).• Swell - is characterised by waves of low height, gentle steepness, long wavelength and a long period.• Wave frequency - the number of waves per minute.
Wave Terminology• Wave Fetch – is the amount of open water over which a wave has passed.• Plunge line – the point at which the wave breaks.• Swash - the body of foaming water which then rushes up the beach, while any returning down to the sea is the backwash.• Wave orbit - the shape of the wave. It varies between circular and elliptical.
The coast as an open system• Landforms are the result of inputs of energy to surface and near-surface materials• At the coast, the main source of energy is waves generated by the wind.• The coast as a system is a highly complex system with many factors influencing its characteristics.• Along any one stretch of coastline, these factors interrelate in a unique way, with each one assuming a different degree of importance.
Questionsa. Using annotated diagram, explain the followingterms: • Wave crest • Wave trough • Wavelength • Wave height b. Explain how coastal landscapes vary on account of human activities and geological structures.