Coastal Environments
There are many different types of environments on earth with specific factors that support every type of environment. One of the more interesting environments we have on earth is our coastal regions. The coast is fascinating when studying geography because this is where the terrestrial and marine life depends on each other. Temperature is also significantly different from the inner continent, which plays a vital role in cooling down the average temperature. This research paper will be providing information about coastal environments such as coastal landforms, coastal ecosystems, coastal climate, temperature, their importance, what they provide for life, as well as how they are formed and how they impact our atmosphere.
The Coasts
The coast is where the land and the sea meet, actually a transition zone with a coastline between them. The coat is made up of two parts; the onshore and the offshore. The onshore extends to the land with up to 60km while the offshore extends out in the sea for up to 370km (pearsonschoolsandfecolleges). The different coast of the world differs in landscapes and ecosystems associated with many factors affecting coasts which include; variation in land and sea features, the difference in weather and climate and also the human activities taking place at different coasts (Pratolongo). Weather and climate form essential factors as it determines the state of the atmosphere. Human activities, settlement, and development affect the coasts too. The land and sea processes affect the physical landforms, which falls into two parts; the terrestrial and marine landforms (Pratolongo).
Land processes
On the land side of the coastline, there are three main processes taking place leading to the formation of terrestrial land landforms;
weathering – the breakdown of rocks into smaller particles. Weathering is caused by several processes; freeze-thaw action, the growth of salt crystals in rocks, breaking by acid rain, and the growth of vegetation (pearsonschoolsandfecolleges).
Erosion – the wearing away of rocks by wind and rain
mass movement – the gravitational influence of the removal of cliff-face material in the form of landslides, rock falls ad slumping.
Marine processes
Marine processes are mainly formed through erosion, transportation, and deposition by Waves. Waves come about as a result of the wind flowing over the surface of the seawater. If the wind is strong enough, waves are set in motion by friction. The stronger the wind, the stronger the waves will be created (Davis). Time and distance traveled by the wind, determine its strength, that is the fetch. At the coast, the water is shallow, and thus the wave results in friction between the water and the sea bed before breaking into the land, i.e., the swash. As the wave is depleted of energy on the beach, it finally falls back down the beach, i.e., backwash (Davis).
The difference in strength between the swash and backwash determines the nature of the wave, whether constructive or destructive. In a constructive wave, the swash is stronger than the backwash, and therefore materials are transported up the beach and deposited there (pearsonschoolsandfecolleges). And for a destructive wave, the backwash is stronger than the swash, and thus, materials are eroded and moved down the beach and even transported along the coast through longshore drift. Materials are eroded in destructive waves in through;
hydraulic action – the cracks and crevices are hit by the waves by forcing air into them, thus extracting materials.
Abrasion – the stones picked up by the waves are hurled in the cliffs and therefore wearing them off.
Corrosion – water dissolves the surface rocks.
The materials carried by the wave are reduced in size over time through Attrition as they collide with each other forming small pebbles and sand. After the materials are eroded, they are moved along the coastline in a longshore drift for a long distance, depending on the size of the particles. Eventually, the particles are deposited to form a marine landform (Trenhaile).
Coastal landforms
Both marine and terrestrial processes lead to the formation of many landforms in the coastal regions. The landforms can be formed through erosive or depositional actions.
Erosional landforms
Erosion leads to common landforms such as the alternation of headlands and bays, forming the coastline aided mostly by destructive waves and the nature of rocks along the coast. The concordant coasts where the rock outcrops run parallel to the sea are often eroded uniformly, thus forming relatively straight coastlines (Sharma). While the discordant coasts where the rock outcrops are at right angles to the sea forms irregular coastline at thus larger headlands and bays. Also, the weaker the rocks along the coastline line, the more erosion will take place.
Headlands are mostly defined by cliffs, and as the destructive waves keep up, they are cut, thus forming a wave-cut notch. The wave-cut notch collapses due to continued undercutting leading to the cliff retreat, but its steep face is maintained and a gentle slope at the base (pearsonschoolsandfecolleges). The continued attack on the headland rocks leads to the formation of other features such as caves, arches, stacks, and even stumps. First, the abrasion and hydraulic action of the waves on the headland forms a cave, and when the process continues, thus enlarging the cave further inside the headland until the cave extends to the other side to form an arch (Sharma). If the roof of the arch is eroded and it finally collapses, it forms a stack which is separated from the headland. Continuous erosion of the stack reduces its size until it forms a flat portion called a stump, which may be visible only during low tides (Pratolongo).
Depositional landforms
Depositional landforms are formed as a result of the accumulation of materials along the coastline. When the accumulation rate of sand, shingle, and mud is higher than the rate at which they are moved away by the waves, results in the formation of these landforms. They are mainly formed under constructive waves (Short). The most common depositional features are beaches, which results from the deposition of materials between the low tide mark and the high tide mark along the coastline (pearsonschoolsandfecolleges). Beaches depict some small features; At the far end from the sea, the larger materials from high tides are deposited and storms forming a storm beach. In the middle, there are materials deposited by average tides to form small ridges called berms, and down the beach; the accumulation of fine particles from small swash and backwash results in beach cusps (Pratolongo).
Other landforms as a result of depositional processes are the spits that are formed when deposition of materials extends across a bay or towards the sea where the coastline changes its course forming long narrow beaches (Davis Jr). Spits a formed when longshore drift is dominant in a particular direction. Spits may develop on a river estuary leading to deposition of sediments and encouraging formation of salt marshes (Davis Jr). A bar may be formed when spits are formed in a bay linking two headlands. The accumulation of water in the landward side of the bar forms a lagoon, for example, the Slapton lagoon in England (pearsonschoolsandfecolleges).
The continued growth of spits towards the sea may result in the stretching and joining an island forming Tombolos, for example, the Chesil Beach linking the mainland to the Portland of south coast England (pearsonschoolsandfecolleges). Tombolos may arise due to dominant longshore drift and offshore sedimentation towards the coast. If the spits extending seaward are triangular, they form a Cuspate foreland that forms due to longshore drift in two directions and resulting in the deposition of materials from two different directions when the coastline changes its direction (Davis).
Other depositional features are the sand dunes, which are formed indirectly from the coastal processes. The sand deposited to form the beach dries up, which are then blown by the wind to form the sand dunes. The formation of sand dunes successively leads to the formation of ridges that are later colonized by vegetation and thus stabilizing them (Yu).
Importance of the coastal landforms
The landforms provide many opportunities for various economic activities on the coast. First, the tourism sector exploits the fine scenery of the sandy beaches on the coast for recreational purposes. Some beaches of the world offer opportunities for the development of golf courses and forms the world-famous (Williams). Secondly, the development of spits on estuaries aids the building of the Marinas as they provide shelter to them. Also, the exposure of some coasts offers opportunities for energy firms to establish wind power generation stations along the coast (Williams). Furthermore, Thermal and nuclear farms are set up on some coasts and, thus, economic exploitation by the energy industry (Williams).
Factors affecting coasts
There are several factors affecting coasts on top of the marine and terrestrial processes affecting the coasts. Some of the factors include the geology of the coast, changes in sea level, and the vegetation cover of the coast.
Geology
The shape of the coastline is dependent on the distribution of the hard and soft rocks along the coastline. Destructive waves strongly erode coastline made up of weak materials such as clay and sands and therefore encouraging the formation of bays. While for hard rocks, the resistance will leave the coastline less eroded (Haslett). The hard rocks often jut out into the sea when the soft rocks are eroded and thus forms the headlands. The nature of rocks also determines the shape of cliffs and the rate of formation of other features from the cliff. And therefore, the geology of the coastline influences the formation of different landforms and the shape of the coastline (Haslett).
Sea-level changes
The sea levels changes are associated with the effects of global warming and climate change. Therefore, low lying coasts will be drowned when the sea level rise and thus reducing the extent of the coast (Haslett). The melting ice and glaciers are responsible for the rising and drowning of the coasts to form the submergent coastlines with its main features being; the drowned glacial valleys to form fjords and the drowned river valleys forming rias. On the other hand, when the sea level falls, emergent coastlines are exhibited and associated with raised beaches and other landforms and increasing the visibility of stacks and stumps that were long drowned (pearsonschoolsandfecolleges).
Vegetation
The vegetation cover of the coast affects the temperature and humidity of the coast as well as determining the stability of the landforms. Vegetation protects and preserves most coastal landforms. The vegetation, however, has to adapt to the high level of salts in the coast.
Human activities
Human activities affect most coastal processes in many ways. The activities include; settlements around the coast, economic developments in the coast such as fishing, the building of ports and harbors which affect most landforms, and coastal management protecting the coastlines from sustained erosion and other destructive activities around the coast (pearsonschoolsandfecolleges).
Coastal ecosystems
Despite the high rate of human activities on the coasts, the coast can still be very rich in biodiversity. The main ecosystems around the coast are the coral reefs, the mangroves, salt marshes, and the sand dunes. Though sand dunes and salt marshes can be found around the world and not only restricted to the coast.
Mangroves
Mangroves are most common within 30 degrees latitude of the equator. Mangroves live on both land and sea along the coastline, thus have its ‘foot’ on both land and water (Davidson-Arnott). Since they live along the coastline, Mangroves are highly subjected to changing environments where sometimes they are completely submerged in water. During low tides, they are completely exposed, and when the tides are average, they live partly exposed (pearsonschoolsandfecolleges). And therefore, mangroves can survive changing conditions and also cope easily with choking mud and heat. Mangroves are of several species of varying sizes ranging from small shrubs species to species of up to 60m in height (pearsonschoolsandfecolleges). All species are well adapted to the environment they inhabit. Mangroves have means of removing excess salts in the saline environment by filtration and breathing roots that stick out of the mud to aid in air acquisition (Davidson-Arnott). They also have buttress roots to aid in low tides and soft grounds
Coral reefs
Coral reefs forms part of the marine ecosystem. Reefs are made up of entirely living organisms. Coral reefs and formed as a result of the deposition of calcium carbonate made up of corals (pearsonschoolsandfecolleges). The survival of coral reefs in the cost is dependent on some factors like; temperature of between 23o C and 25o C for their best growth but can still grow in temperatures lower to a minimum 18o C water temperature, shallow water because corals need light to grow and thus are limited to up to a maximum of 25m water depth and also salinity is a factor in coral growth since they are marine creatures and can only grow in saline environments (Davidson-Arnott). Furthermore, corals need well-oxygenated water and thus thrive well in water of strong wave action to ensure that they get oxygen or they be exposed to air and the water needs to be clean and free from sediments for enough sunlight penetration (Davis Jr).
Salt marshes
Salt marshes are an ecosystem of the intertidal zone, just like the mangroves. They live in the midway between terrestrial and the muds in the marine. They develop in locations that are sheltered from the sea, especially the head of bays and some estuaries where water is brackish, i.e., partly salty and partly fresh (Davidson-Arnott).
Sand dunes
Sand dunes at the coast are formed due to wind action on dry beach sand and deposition to form ridges (pearsonschoolsandfecolleges). Their development is dependent on some factors such as; the presence of a wide beach with a large quantity of sand, the presence of prevailing winds from the sea along the shore, and a favorable location for the accumulation of the sand (Davis). The stability of the sand dunes is provided by vegetation cover
Importance of the Coastal ecosystems
The coastal ecosystems provide a lot of importance. Most ecosystems aid people to get valuable goods and services from the coast. They include the provision of fish protection from storms, availability of fish, seaweed, salt, land for settlements, protection of biodiversity, materials for constructions such as sand and timber, and also form habitats for wildlife. There are other importance from each ecosystem (Davidson-Arnott);
The mangroves protect against floods where many people die from tsunamis on open coasts, but few die when mangroves cover the coasts. They also provide construction materials and modify the climate of the coast and protect the other landforms like the sand dunes by improving their stability (pearsonschoolsandfecolleges).
The coral reefs provide for biodiversity with many species of different organisms, such as fish mollusk and coral. Coral reefs protect low laying coast from destructive storms. They also provide food in the form of fish to many and attract tourists for recreational activities and, thus, economic opportunities (Burke).
Salt marshes and coastal sand dunes provide less importance to economic development, but they still attract tourists (Davidson-Arnott).
The coastal climate and its importance
Climatic conditions in the coasts affect many activities. The coastal ecosystems are adapted to the atmospheric and marine climates, and thus climate change will automatically lead to changes in the ecosystems (Gourlie). The daily changes in humidity and wind also affect the development of some landforms such as sand dunes and spits while also increasing atmospheric moisture. Temperature determines the development of coastal ecosystems and, more so, their health. The corals, for example, thrive over a small range of heat, and thus a small deviation in temperature and the change persist for few days; a significant difference will be noted in the corals (Short). The El Nino in 2015, which ran for almost a year, caused considerable changes in oceanic temperatures and the coastal atmospheric moisture and thus altering the distribution of the corals and other coastal ecosystems (Short). Importance of climate for coastal ecosystems. Small deviations in temperature have depicted adverse effects on the coastal ecosystems. For example, the giant kelp has decline off the eastern and southern coasts of Australia as a result of an increase in coastal temperatures (Gourlie). Also, the embryo development of a turtle occurs in a narrow temperature range, and thus changes in temperature are a potential risk for turtle extinction.
Climatic conditions affect the shape of the coastline settlements. The settlements are based on temperate climates with regularity in rainfall and the availability of freshwater. River floods are a factor when building houses, and also the level of erosion by storms affects the location of the settlements (Haslett). The building of ports, harbors, and jetties depends on the variation of the tides and the amount of ice and glacial melts associated with changes in temperature.
Economic activities in the coast are influenced by the development of infrastructures to support it. The sea surface temperatures also affect fisheries as it impacts the availability of fish. The recreational activities depend on the coastal temperatures and the atmospheric humidity at every given time (Short).
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