Unit 8 (Revision Guide) Flashcards
How are different types of waves generated and what effect do they have on beaches?
Original: Waves are created by wind pushing on the sea’s surface. Constructive waves build up beaches by depositing sand, while destructive waves erode beaches by dragging sand away.
Simple: Waves are created by wind pushing on the sea’s surface. Constructive waves build up beaches by adding sand, while destructive waves erode beaches by taking sand away.
What factors determine the different nature of waves breaking at a shoreline?
Original: Wind strength, how long the wind blows, the distance it travels (fetch), and the shape of the coast affect how waves break. Waves also bend (refract) as they approach shallow water.
Simple: Wind power, how long it blows, how far it travels, and the shape of the coast decide how waves break. Waves also bend when they get close to shore.
What are the characteristic features of constructive waves and how do they affect beach shape?
Original: Constructive waves are low and gentle, with strong swash that pushes sand onto the beach, making it wider and flatter. They come slowly, about 6–8 times per minute.
Simple: Constructive waves are small and calm, helping build beaches by adding sand. They arrive slowly, making beaches wider.
What are the characteristic features of destructive waves and how do they affect beach shape?
Original: Destructive waves are high and powerful, with strong backwash that pulls sand off the beach, making it steeper. They come quickly, about 10–12 times per minute.
Simple: Destructive waves are tall and strong, taking sand away and making beaches steeper. They come quickly and often.
What is hydraulic action in coastal erosion?
Original: Hydraulic action happens when waves trap air in cracks of rocks. The trapped air pushes against the rock, making it crack and break.
Simple: Hydraulic action is when waves force air into cracks in rocks, causing them to break apart.
What is wave quarrying in coastal erosion?
Original: Wave quarrying is when powerful waves smash against cliffs, breaking off pieces of rock.
Simple: Wave quarrying happens when waves hit cliffs hard enough to break rocks off.
What is abrasion (corrasion) in coastal erosion?
Original: Abrasion is when waves throw sand and rocks against cliffs, scraping and wearing them down like sandpaper.
Simple: Abrasion happens when waves carry rocks and sand that scrape cliffs, wearing them down.
What is the role of rock type and structure in the formation of coastal erosional landforms?
Original: Rock type (lithology) and structure significantly influence coastal erosion and landform development. Hard rocks like granite and limestone resist erosion, forming steep cliffs and headlands. Soft rocks like clay and shale erode easily, creating bays and gentle slopes. Rock structure, including the angle of bedding planes, joints, and faults, affects the shape and stability of cliffs. Horizontal strata form steep cliffs, while inclined strata produce less steep profiles.
Simple: Rock type and structure affect how easily coasts erode and what shapes they form. Hard rocks like granite resist erosion, making steep cliffs. Soft rocks like clay erode easily, creating bays. The way rocks are layered or cracked also affects cliff shapes.
How do marine and sub-aerial processes contribute to the formation of coastal erosional landforms?
Original: Marine processes like hydraulic action, abrasion, and corrosion erode cliffs and form features such as caves, arches, stacks, and stumps. Sub-aerial processes, including weathering (chemical, biological, and physical) and mass movements (landslides, slumping), weaken rock structures and contribute to cliff retreat and the development of wave-cut platforms and notches.
Simple: Marine processes (like waves) erode cliffs and make features like caves and arches. Sub-aerial processes (like weathering and landslides) weaken cliffs, helping them break down faster. Both work together to shape the coast.
How are spits, bars, and tombolos formed along coastlines?
Original: Spits are formed by longshore drift, which transports sediment along the coast, depositing it when the coastline changes direction or where water energy decreases. Bars develop when a spit extends across a bay, connecting two headlands and trapping water behind to form a lagoon. Tombolos occur when longshore drift deposits sediment between an island and the mainland, creating a land bridge. These formations depend on sediment supply, wave direction, and tidal conditions.
Simple: Spits form when waves move sand along the coast, creating long, narrow beaches. Bars form when spits connect across a bay. Tombolos happen when sand links an island to the mainland. All need enough sand and the right wave conditions.
How do waves influence the shape of beaches?
Original: Constructive waves, with strong swash and weak backwash, deposit sediments, forming wide, gently sloping beaches with berms and ridges. Destructive waves, characterized by strong backwash, erode beaches, removing sediment and creating steep profiles. Wave refraction concentrates energy on headlands and disperses it in bays, influencing beach morphology and the development of features like cusps, storm ridges, and beach cusps.
Simple: Gentle waves build up beaches by bringing sand, while strong waves erode them by pulling sand away. The direction and strength of waves also shape features like ridges and cusps on beaches.
What is meant by the term coastal sediment cell?
Original: A coastal sediment cell is a section of coastline bordered by natural barriers (headlands, estuaries) within which sediment movement is largely self-contained. It consists of sources (river deposits, cliff erosion), transfer paths (longshore drift, currents), and sinks (beaches, offshore bars). Sediment cells operate as closed systems with limited exchange of material between adjacent cells.
Simple: A coastal sediment cell is a stretch of coast where sand and rocks move in a closed loop, without mixing much with other areas. It has sources of sand, paths for movement, and places where sand settles.
How do sediment cells contribute to the formation of coastal landforms?
Original: Within sediment cells, material eroded from sources like cliffs is transported by longshore drift and deposited at sinks, forming features such as beaches, spits, and dunes. The balance between sediment supply and removal within a cell influences coastal stability and landform evolution, with sediment deposition creating accretional landforms and sediment deficit leading to erosion.
Simple: Sediment cells move sand and rocks along the coast, shaping beaches, spits, and dunes. When there’s enough sand, it builds new landforms; when there isn’t, erosion wears landforms away.
What are the sources of coastal sediment, and how is it transported and deposited?
Original: Coastal sediment sources include river discharge, cliff erosion, offshore bars, and biological contributions (e.g., shell fragments). Sediment is transported by longshore drift, tidal currents, and wave action. Deposition occurs when wave energy decreases, forming beaches, spits, bars, and dunes. Tidal processes and storm events can also influence sediment distribution and deposition patterns.
Simple: Coastal sediment comes from rivers, eroding cliffs, and the sea. Waves and currents move it along the coast. When waves lose energy, they drop the sand, creating beaches, spits, and dunes.
What are the main conditions required for the formation of coral reefs?
Original: Coral reefs require warm water temperatures (generally between 23°C and 26°C, with a maximum of 33°C), sufficient light for photosynthesis, clear and shallow waters (up to 50 m deep), salinity between 32–42 ppt, a firm base for attachment, limited water turbulence, and a supply of plankton for food.
Simple Terms: Coral reefs need warm water (23–26°C), lots of sunlight, clear and shallow water (up to 50 m deep), salty water (32–42 ppt), a hard surface to attach to, calm waters, and plankton for food.
What are the main threats to coral reefs?
Original: The main threats to coral reefs include global warming (leading to increased sea temperatures), sea-level rise, various forms of pollution (such as runoff, oil spills, and plastic waste), and physical damage from human activities like fishing, anchoring, and coastal development.
Simple Terms: The biggest threats to coral reefs are global warming, rising sea levels, pollution (like chemicals and plastic), and damage from fishing, boats, and building on coasts.
How does rising sea temperature threaten coral reefs?
Original: Rising sea temperatures (by 1–2°C above the maximum) cause coral bleaching by stressing corals, leading them to expel the symbiotic zooxanthellae algae that provide them with food and color. Without these algae, corals lose their color and vital energy sources, making them more susceptible to disease and death.
Simple Terms: Warmer water makes corals lose the tiny algae that live in them, causing them to turn white (bleaching) and making it hard for them to survive.
How does sea-level rise impact coral reefs?
Original: Sea-level rise affects coral reefs by submerging them deeper, reducing the light available for photosynthesis. Rapid sea-level rise can outpace the growth of corals, causing them to die. Additionally, increased sedimentation from coastal erosion can smother corals, blocking sunlight and disrupting their ability to feed and grow.
Simple Terms: If the sea level rises too fast, corals can’t grow quickly enough to stay near the sunlight they need, which can cause them to die.
How does pollution threaten coral reefs?
Original: Pollution, such as agricultural runoff containing nitrates and phosphates, leads to nutrient enrichment that promotes algal blooms. These blooms reduce the light available to corals and increase competition for space and resources. Oil spills and toxic chemicals also poison coral reefs directly, while plastic debris can physically damage and suffocate corals.
Simple Terms: Pollution from farms and cities makes algae grow too much, blocking sunlight and using up oxygen. Oil spills and plastic also harm corals directly.
How does physical damage threaten coral reefs?
Original: Physical damage to coral reefs is caused by activities like blast fishing, trawling, anchoring, and coastal construction. These activities can break coral structures, disturb sediment, and make it difficult for corals to recover. Coastal development can also lead to increased sedimentation, which smothers corals and reduces light penetration needed for photosynthesis.
Simple Terms: Fishing with explosives, dragging nets, boat anchors, and building near coasts can break corals and cover them with dirt, making it hard for them to survive.
What is the role of the “Reefs at Risk” programme?
Original: The “Reefs at Risk” programme assesses the threats to coral reefs by analyzing data on coastal development, marine-based pollution, over-exploitation from fishing, and sedimentation from river runoff. It categorizes reefs into high, medium, or low-risk levels based on the severity of these threats, helping to prioritize conservation efforts and management strategies.
Simple Terms: The “Reefs at Risk” programme checks how much danger coral reefs are in from things like pollution, too much fishing, and dirt from rivers, helping people decide where to protect them first.
What management strategies can help protect coral reefs?
Original: Effective management strategies include establishing marine protected areas to limit fishing and tourism impacts, regulating and reducing sources of pollution, restoring damaged reefs through coral transplantation or artificial structures, controlling invasive species like the crown-of-thorns starfish, and raising public awareness about the importance of coral conservation. Additionally, addressing climate change by reducing carbon emissions is crucial for the long-term survival of coral reefs.
Simple Terms: Protecting coral reefs involves setting up safe areas where fishing and boating aren’t allowed, cleaning up pollution, fixing broken reefs, and telling people why corals are important. Cutting down on greenhouse gases also helps in the long run.
How can the management of a coastline create more problems than it solves?
Original: Management strategies, like vertical sea walls at Unawatuna beach, caused wave reflection, increasing erosion and beach loss. Inadequate planning, such as using undersized rocks for breakwaters, also led to ineffective protection and higher maintenance costs.
Simple: Bad planning, like using straight sea walls, can cause more erosion and damage, as seen at Unawatuna beach.
What factors should be considered when evaluating the success of coastal protection methods?
Original: Success depends on reducing erosion effectively, cost-efficiency, long-term sustainability, and minimizing negative impacts on natural coastal processes, as seen with the mixed results of hard and soft engineering at Unawatuna beach.
Simple: How well they stop erosion, cost, if they last long, and if they harm the environment.
What are some threats that may affect coastlines?
Original: Threats include coastal erosion, rising sea levels, storm surges, and human activities that alter natural sediment movement, all of which were challenges faced at Unawatuna beach following the 2004 tsunami.
Simple: Erosion, rising sea levels, storms, and human activities.
What are some possible ways to protect coasts from threats like erosion and rising sea levels?
Original: Hard engineering methods, such as sea walls and breakwaters, aim to prevent erosion directly, while soft engineering methods, like beach nourishment, involve adding sand to beaches to absorb wave energy, as attempted at Unawatuna beach.
Simple: Using sea walls and breakwaters (hard methods) or adding sand to beaches (soft methods).
