coasts

#separator:tab #html:true Describe some inputs in coastal systemssolar radiation (winds, waves, freeze-thaw, photosynthesis) gravity of moon & sun (tides) gravity of earth (mass movement) fluvial deposition beach nourishment LSD Describe some processes in coastal systemsmarine erosion (hydraulic action, abrasion) transportation & longshore drift deposition sub-aerial weathering (biological, freeze-thaw, chemical) mass movement (rockfall, slumping, sliding) aeolian erosion (eg deflation), transportation & deposition Explain the concept of sediment cellsa stretch of coastline where the movement of material is largely self-contained. contains areas of erosion, transportation and deposition. essentially a closed system occasional transfer of sediment between cells eg in storms. in dynamic equilibrium meaning rate of inputs = rate of outputs if a factor changes the system will correct itself so sediment cells are negative feedback systems. Explain how coasts can be viewed as systemsinputs, processes, stores and outputs. solar radiation causes winds and so waves allows for biological weathering (plants / photosynthesis) allows for mechanical weathering (water cycle so freeze-thaw). gravitational potential energy from the Earth causes mass movement from the Moon causes tides. all these energy inputs cause an input of sediment. other sediment inputs include fluvial deposition & beach nourishment. processes of transportation move sediment before it is deposited traction, saltation, suspension, solution. transportation may be in the form of longshore drift. outputs are deposited sediment forming landforms eg spits, bars, tombolos. Explain how material flows through coastal systemsinputs / sources fluvial deposition weathering & mass movement marine erosion aeolian erosion processes transportation by traction, saltation, suspension and solution may be in the form of longshore drift. aeolian transportation by saltation, suspension, creep outputs deposition as water slows down / loses energy forming new landforms beaches, spits, bars, tombolos, salt marshes Explain how energy flows through coastal systemsinputs solar radiation gravitational potential from Earth & Moon transfers kinetic energy in winds, waves & tides chemical energy in vegetation kinetic energy causes erosion & transportation deposition when energy not transferred up beach (gentle beach profile) Explain the effect of wind speed on coastal landscape systemsa higher wind speed increases wave energy so increases rate of marine erosion and increases rate of longshore drift (if wind at oblique angle). also increases rate of aeolian processes erosion by deflation as wind moves smaller lighter sand particles as well as transportation by suspension, saltation & creep & transportation to form dunes. Explain the effect of wind direction on coastal landscape systemsif wind has travelled from a direction where it has been unobstructed fror a long distance there is a long fetch so waves have more energy eg Blakeney in Norfolk with annual average power 9 kW/m wave front increasing rate of marine erosion. if wind is travelling at an oblique angle swash may transport sediment at this angle before it is moved back at 90 by backwash so longshore drift. Explain the effect of winds on coastal landscape systemsfactors are speed and direction (and frequency). a high wind speed & long fetch are both factors which increase wave energy (e.g. Blakeney, Norfolk 9 kW/m) so increase the rate of marine erosion. if wind travels at an oblique angle swash may transport sediment at this angle before it is moved back at 90 by backwash so this is a drift-aligned beach. high wind speed also increases rate of aeolian processes erosion by deflation as wind moves smaller lighter sand particles as well as transportation by suspension, saltation & creep & transportation to form dunes. Explain the effect of lithology on coastal landscape systemsigneous & metamorphic rocks are more resistant to erosion / weathering / mm so are more likely to form steep cliffs. sedimentary rocks are generally less resistant eg unconsolidated sand / silt / clay so more likely to form gently sloping beach. some rocks may be more susceptible to chemical weathering eg limestone & chalk by carbonation eg rocks containing iron by oxidation. Explain the effect of geological structure on coastal landscape systemssometimes bands of different rock types run perpendicular to the coast called discordant coastlines eg around Swanage Bay in Dorset which causes the creation of headlands & bays due to differential erosion / weathering / mm. concordant coastlines have bands of different rock types run parallel to the coast which tend to be relatively uniform. porous rocks eg chalk have tiny air spaces other permeable rocks have many joints, allowing water to seep in eg limestone so more vulnerable to physical weathering eg freeze-thaw. if permeable strata above impermeable strata water can percolate until it reaches the bedding plane lubricating the impermeable rock so creating an unstable situation and vice versa. horizontally bedded & flat or lanward-dipping strata creates a stable configuration so cliffs have steep, vertical profiles. if strata dip seawards the cliff is less stable as more vulnerable to mass movement eg rockfalls so cliff profiles tend to have the same angle of dip as the bedding planes. Name ways geological structure affect coastal landscape systemsconcordant vs discordant coastlines porous & permeable rocks + their arrangement angle of dip of bedding planes Explain the formation of caves, arches, stacks and stumpserosional landforms (predominantly hydraulic action & abrasion) eg Old Harry (stack) & Old Harry's Wife (stump) in Dorset. energy concentrated onto headlands due to wave refraction so any points of weakness (faults / joints) are exploited by erosion forming a cave the process continues and the cave expands all the way through the headland forming an arch the arch may collapse due to gravity & weathering eg freeze thaw forming a stack which may then itself collapse & form a stump. Name erosional landformsheadlands & bays cliffs shore platforms geos & blow holes caves, arches, stacks & stumps Name depositional landformsbeaches spits onshore bars tombolos salt marshes Explain the formation of geosgeos are narrow, steep-sided inlets eg Huntsman's Leap in Pembrokeshire. points of weakness (joints / faults) exploited by marine erosion forming a cave in the cliff. as these caves tunnel further in the roof may collapse due to gravity & weathering. Explain the formation of a blow holeeg there is a blowhole in Trevone, Cornwall. points of weakness (joints / faults) exploited by marine erosion forming a cave in the cliff. as these caves tunnel further in part of the roof collapses along a master joint due to gravity & weathering so a vertical shaft forms that reaches the cliff top. Give an example of a blow holethere is a blowhole in Trevone, Cornwall Give an example of a geoHuntsman's Leap in Pembrokeshire Explain the formation of shore platformshorizontal or gently sloping rock in the intertidal zone erosional landform. when destructive waves break repeatedly on cliffs marine erosion forms a wave-cut notch in the intertidal zone this notch expands so support for the above rock strata weakens this rock eventually collapses due to gravity (weathering may contribute) waves remove debris at base of cliff giving cliff a steep profile with a shore platform left below the original location of the notch. often quite dissected by abrasion due to rock debris dragged across marine organisms eg algae can accelerate weathering when platform exposed solution, freeze thaw and salt crystallsation can all occur. max width 500m Explain the effect of tidal range on coastal landscape systemsa low tidal range means marine erosion is more concentrated on less land area creating deeper wave cut notches so more undercutting causing cliffs to retreat faster. a higher tidal range increases the area affected by weathering particularly on shore platforms particularly salt crystallisation and freeze thaw. Name methods of bar formationswash aligned beaches: sand bank pushed onshore by constructive waves drift aligned beaches: longshore drift continues despite change in coastline direction Explain the formation of onshore barsbars are ridges of sand/shingle which join two headlands lagoon forms behind bar eg Loe bar in Cornwall. swash aligned beaches sand bank develops offshore and is pushed onshore by constructive waves in periods of sea level rise eg Flandrian Transgression where sea levels rose 120m drift aligned beaches prevailing wind at an oblique angle swash carries sediment up beach at that angle backwash carries back at 90 so overall movement along (longshore drift) continues after coastline changes direction, forming spit spit joins two headlands Explain the formation of tomboloslandforms of deposition when sediment extends from the mainland and connects to an offshore island eg Chesil Beach in Dorset which connects to the Isle of Portland. longshore drift (drift aligned beaches) prevailing wind is at an oblique angle swash carries sediment up beach at that angle backwash pulls sediment back perpendicular to the coastline causing an overall movement of sediment along the beach (LSD) this continues after the coastline changes direction, forming spit spit continues until it happens to reach an offshore island sea level rise period of postglacial sea level rise ending 6000 years ago called the Flandrian Transgression (sea levels rose 120m) so more water with more energy to carry sediment. in the case of tombolos, waves bend around an island & slow down & refract so they lose energy & deposit sediment forming a salient, which grows & joins island. Explain the formation of a spitspits are depositional landfordms long, narrow beaches of sand or shingle that are attached to the land at one end and extend across a bay, estuary or indentation in a coastline eg Blakeney Point in Norfolk on drift aligned beaches prevailing wind is at an oblique angle swash carries sediment up the beach at that angle backwash carries back perpendicular to the coastline so overall movement along the beach (longshore drift) coastline changes direction yet longshore drift continues recurved end may form due to wave refraction or change in wind direction. Explain the formation of a salt marshsalt marshes are vegetated areas of deposited silts and clays regularly flooded by seawater. formed in low-energy environments eg in estuaries or behind spits salt-tolerant plant species eg eelgrass trap sediment increasing the height of the marsh stems and leaves act as baffles (trapping) while roots stabilise the sediment What is a bar?ridge of sand/shingle which joins two headlands lagoon forms behind bar eg Loe bar in Cornwall What is a salt marsh?vegetated areas of deposited silts and clay regularly flooded by seawater features of low-energy environments eg estuaries and behind spits Name sources of coastal sedimentterrestrial fluvial deposition weathering and mass movement marine erosion aeolian deposition longshore drift offshore marine deposition human beach nourishment Name terrestrial sources of coastal sedimentfluvial deposition weathering and mass movement marine erosion aeolian deposition longshore drift Explain the formation of cliffscliff profile depends on wave energy and angle of bedding planes. for destructive waves and horizontal bedding planes marine erosion causes undercutting in the intertidal zone leaving an overhang which then collapses the waves (strong backwash) remove the debris so the cliff retreats and the steep / vertical profile is maintained. if waves have less energy debris may remain so cliff profile is more gently sloping What is a shore platform?horizontal or gently sloping rock in the intertidal zone erosional landform Explain how physical factors influence the formation of landforms in a high energy coastlineNorfolk coastline geology both NE and NW cliffs have chalk NE cliffs also have weakly consolidated sands and gravels so high erosion rates in both (1-71cm/year NE and 11cm/year NW) forming steep cliffs and shore platforms in both. wind wind direction drives LSD west so NE cliffs more vulnerable to erosion providing an input of sediment for the coastline further west depositional landforms eg beaches, spits, salt marshes eg at Blakeney Point there is a spit and salt marsh (in the shingle ridges and sandy beaches). long fetch so high wave energy, particularly for NW cliffs. waves type eg destructive vs constructive Explain how geology influences the formation of landforms in a high energy coastlineNorfolk coastline. both NE and NW cliffs contain chalk so vulnerable to carbonation and NE also consist of weakly consolidated sands and gravels so high rates of coastal retreat in both (1-71cm/year NE and 11cm/year NW) forming steep cliffs and shore platforms in both providing sediment input for depositional landforms further east eg beaches, shingle ridges, sand dunes, estuaries, spits, salt marshes Explain how wind influences the formation of landforms in a high energy coastlineNorfolk coastline. wind direction drives LSD west so NE cliffs more vulnerable to erosion providing an input of sediment for the coastline further west depositional landforms eg beaches, spits, salt marshes (in the shingle ridges and sandy beaches). long fetch so high wave energy, particularly for NW cliffs. Explain the inter-relationship of landforms in a high energy coastlineNorfolk. wind orientation drives LSD west linking sediment input from high erosion at NE cliffs to deposition further east allowing formation of beaches, shingle ridges, estuaries, salt marshes, sand dunes e.g. spit at Blakeney Point. there is a relationship between cliffs, wave cut notches and shore platforms (NE and NW) wave cut notches form inside cliffs - as they enlarge they cause cliffs to retreat which leaves behind a shore platform max width 500m after which waves can no longer erode cliff due to friction. Explain how and why a high energy coastline changes in the short termNorfolk. cliff collapse occurs fairly frequently eg at Happisburgh in January 2021 due to relatively weak lithology cliffs composed of chalk and weakly consolidated sand and gravel also occurs when cliffs are saturated after heavy rain more likely to occur as houses built on cliffs, increasing their weight. coastal management Explain how and why a high energy coastline changes in the long termNorfolk. spits form over thousands of years if prevailing wind is at an oblique angle LSD occurs (drift aligned beach) on the Norfolk coastline LSD travels west so sediment inputs from NE cliffs transported then deposited eg spit at Blakeney Point lengthened by >100m between 1886 and 1925 spit formation can lead to the formation of salt marshes behind which can take several decades. Explain how and why a high energy coastline changesNorfolk short term  cliff collapse occurs fairly frequently eg at Happisburgh in January 2021 due to relatively weak lithology cliffs composed of chalk and weakly consolidated sand and gravel also occurs when cliffs are saturated after heavy rain more likely to occur as houses built on cliffs, increasing their weight. long term spits form over thousands of years if prevailing wind is at an oblique angle LSD occurs (drift aligned beach) on the Norfolk coastline LSD travels west so sediment inputs from NE cliffs transported then deposited eg spit at Blakeney Point lengthened by >100m between 1886 and 1925 spit formation can lead to the formation of salt marshes behind which can take several decades. emergentsea level fall sea level fallemergent submergentsea level rise sea level risesubmergent Name landforms of emergenceraised beaches abandoned cliffs marine terraces Name landforms of submergencerias fjords shingle beaches barrier island Explain how climate change has caused sea level riseeustatic sea level rise is an absolute rise in sea level, occurring in warming climates caused by continental ice caps / sheets melting so more water in oceans and thermal expansion of water, so same amount of water takes up more volume. isostatic subsidence is a relative rise in sea level the main cause of which is ice sheets compressing the lithosphere in glacial periods. example the most recent period of eustatic sea level rise is the Flandrian Transgression from 18,000 to 6,000 years ago as sea levels increased by 120m due to a warming climate after the last glacial period. Explain how climate change has caused sea level falleustatic sea level fall is an absolute fall in sea level, occurring in cooling climates caused by continental ice caps / sheets forming so less water in oceans and thermal contraction of water, so same amount of water takes up less volume. isostatic rebound is a relative fall in sea level the main cause of which is ice sheets melting, allowing the lithosphere to uplift. example eg 125,000 years ago sea level was 8m higher than today during the Sangamonian Interglacial global temperatures are now over 2 degs lower so sea level is lower as well. Explain the influence of sea level fall in forming different landformssea level marine regressions cause emergent landforms to form there is eustatic sea level decrease in cooling climates due to continental ice caps / sheets forming and thermal contraction of water sea level can also fall due to isostatic rebound, which may be caused by deglaciation. landforms coastal landforms are left a few metres inland and above the HWM former shore platforms / beaches become raised beaches and marine terraces cliffs become abandoned cliffs often w/ wave cut notches and caves. sometimes there is a series of terraces and abandoned cliffs as new beaches / cliffs etc form before sea level falls again eg in western Scotland platforms are found at 8, 15, and 30m above sea level. Explain the influence of geomorphic processes on landforms of emergenceraised beaches, marine terraces, abandoned cliffs formation marine processes will have been responsible for forming these landforms in the first place ie before the marine regression (sea level fall). cliffs were shaped by marine erosion creating wave cut notches creating overhangs, which along with weathering caused collapse (mass movement) cliff profile was also shaped by transportation of debris away from base of cliff collapse created wave cut platform which later became raised beach / marine terrace this may have been dissected by abrasion as rocks were dragged across the geomorphic process of marine erosion limited its width to 500m as that is the approximate point where friction prevented further erosion. larger scale shape of abandoned cliffs may be shaped by differential erosion (if lithologies vary) there may even be caves, stacks and stumps. present day change since these landforms are above the HWM, it is now only sub-aerial processes which influence them e.g. biological weathering, freeze-thaw weathering, oxidation, carbonation, landslides Explain the influence of sea level rise in forming different landformssea level marine transgressions cause submergent landforms to form there is eustatic sea level rise in warming climates due to continental ice caps / sheets melting and thermal expansion of water sea level can also rise due to isostatic subsidence due to glaciation. barrier islands offshore bars can be driven onshore by rising sea level forming a barrier island eg Chesil Beach formed as sea level rose 120m during Flandrian Transgression. rias rias rias are drowned river valleys eg those found in Devon and Cornwall in the lower course, the entire river and surrounding floodplain may be submerged however in the middle and upper course, the tops of the valley sides remain exposed exposed valley sides are quite gently sloping. in plan view, they tend to be winding, reflecting the original route of the river and valley fjords fjords are drowned glacial valleys glacial processes create a U-shaped valley which is then flooded when threshold is below sea level found in high altitude locations such as Norway. Explain the formation of barrier islandsa period of sea level rise is called a marine transgression can be eustatic in a warming climate due to continental ice caps / sheets melting and thermal expansion of water. offshore bars can be driven onshore by rising sea level forming a barrier island eg Chesil Beach formed as sea level rose 120m during Flandrian Transgression Explain the formation of riassea level marine transgressions cause submergent landforms to form there is eustatic sea level rise in warming climates due to continental ice caps / sheets melting and thermal expansion of water sea level can also rise due to isostatic subsidence due to glaciation. rias rias are drowned river valleys eg those found in Devon and Cornwall in the lower course, the entire river and surrounding floodplain may be submerged however in the middle and upper course, the tops of the valley sides remain exposed exposed valley sides are quite gently sloping. in plan view, they tend to be winding, reflecting the original route of the river and valley Explain the formation of fjordssea level marine transgressions cause submergent landforms to form there is eustatic sea level rise in warming climates due to continental ice caps / sheets melting and thermal expansion of water sea level can also rise due to isostatic subsidence due to glaciation. fjords fjords are drowned glacial valleys glacial processes create a U-shaped valley which is then flooded when threshold is below sea level. Use a case study to explain the reasons for coastal managementOverstrand. human popular tourist destination with beach, hotels and guest houses with 6,000 jobs in tourism and a water treatment plant which would cost £1.6 million to replace physical cliffs prone to mass movement eg rotational slumping because top layer made up of unconsolidated material which absorbs rain, increasing the weight of the cliff water can permeate through sandstones before meeting clay which is impermeable so water lubricates the bedding plane, creating an unstable situation causing mudflows and landslides for marine erosion to remove debris at the base of the cliff. List the coastal management techniques at Overstrandgroynes sea wall cliff drainage gabions revetments Use a case study to explain the intentional impacts of coastal management on processes and flows of material and energyOverstrand. groynes disrupt longshore drift and so disrupt this flow of material reducing marine erosion as wave energy is absorbed by the sediment. wave energy reflected by curved sea walls. revetments absorb wave energy and reduce sediment transfer from cliffs to beach. cliff drainage reduces mass movement eg rotational slumping by reducing the weight of the cliff, particularly after heavy rain again reducing beach's sediment store Use a case study to explain the intentional impacts of coastal management on landformsOverstrand. groynes build up beach particularly noticeable on the updrift side of the groyne. revetments reflect wave energy while allowing sediment to pass through so beach builds up behind revetments. cliff more stable and vertical due to drainage pipes which reduce mass movement eg rotational slumping. Use a case study to explain the reasons for economic development on the coastNew Zealand nearshore dredging along the Mangawhai-Pakiri coastline of NZ for over 70 years uses of sand include construction and manufacturing concrete and glass in this location there is a high-quality source of sand which is suitable for construction it is just 50km north of Auckland (1/3 of NZ's population) so very convenient Nile delta Aswan High Dam built in 1964 Grand Ethiopian Renaissance Dam built from 2011-2020 plans for more projects in future. to generate hydroelectric power to extract water for irrigation to reduce flooding. Use a case study to explain the unintentional impacts of economic development on the coastNile delta the Aswan High Dam was constructed in 1964 before the dam was constructed, the Nile's annual flood deposited 120 million tonnes of silty mud today the sediment yield is negligible, meaning rates of erosion are now higher than of deposition. currently there are concerns over the Grand Ethiopian Renaissance Dam (built from 2011-2020) where Nile water has been diverted to fill the reservoir behind the dam further reducing the volume of water and sediment reaching the delta more dams are proposed so this challenge is likely to worsen over time. New Zealand nearshore dredging along the Mangawhai-Pakiri coastline of NZ for over 70 years from 1994 to 2004 the rate of extraction was 165,000 m3 per year this output of sediment is naturally replaced very slowly with extraction rates at Pakiri Beach exceeding inputs by a factor of 5 therefore the sand supply of dunes, beaches and the sea bed is depleted and the coast retreats Use a case study to explain how physical factors influence landforms in a low energy environmentNile delta landforms are fluvial for inland region (the delta plain) and marine for coastal region climate the mean annual rainfall in the catchment area of the River Nile is about 600mm the level of precipitation determines the river discharge of the Nile, which then determines volume of sediment carried having a high enough river discharge is critical as fluvial deposition is the main sediment input, forming the delta. river discharge varies over the year as much of the river discharge comes from Ethiopia's summer monsoon rains meaning sometimes there is flooding, forming levees on the banks and crevasse splays on the floodplain if levees are breached. winds northwesterly winds prevail over the sea for most of the year (55-60% of the time) causing sediment to move in an eastward direction (also caused by longshore currents) winds also directly shape the aeolian dunes in the region e.g. those at Gamasa geology the geology of the catchment area is varied the Nile's sediment load is 30% clay, 40% silt and 30% fine sand directly influencing the nature of the delta itself as well as the levees and crevasse splays Use a case study to explain how climate influences landforms in a low energy environmentNile delta. the mean annual rainfall in the catchment area of the River Nile is about 600mm the level of precipitation determines the river discharge of the Nile, which then determines volume of sediment carried having a high enough river discharge is critical as fluvial deposition is the main sediment input, forming the delta. much of the rainfall in the catchment area comes from Ethiopia's summer monsoon rains and so the Nile's discharge varies over the year meaning in summer there is flooding, forming levees on the banks and crevasse splays on the floodplain if levees are breached Use a case study to explain how wind influences landforms in a low energy environmentNile delta. northwesterly winds prevail over the sea for most of the year (55-60% of the time) causing sediment to move in an eastward direction (also caused by longshore currents) winds also directly shape the aeolian dunes in the region e.g. those at Gamasa Use a case study to explain how geology influences landforms in a low energy environmentNile delta. the geology of the catchment area is varied the Nile's sediment load is 30% clay, 40% silt and 30% fine sand directly influencing the nature of the delta itself as well as the levees and crevasse splays Use a case study to explain how landforms are interrelated in a low energy environmentNile delta. levees breached if river discharge is very high, water may breach the levees which causes it to spill out onto the surrounding land and velocity decreases due to friction this causes deposition, forming crevasse splays in areas between distributaries finer particles are distributed further, creating the rich alluvial floodplain. the breaching of levees can also cause a new distributary to form as the water spills over the banks and starts eroding a new path. longshore drift northwesterly winds (55-60% of the time) cause sediment to move eastwards this sediment is then used to form sandy beaches, spits, lagoons, salt marshes and dunes e.g. those at Gamasa these landforms are interrelated because they share the same source of sediment Use a case study to explain how landforms are interrelated in a low energy environment (levees breached)Nile delta. if river discharge is very high, water may breach the levees which causes it to spill out onto the surrounding land and velocity decreases due to friction this causes deposition, forming crevasse splays in areas between distributaries finer particles are distributed further, creating the rich alluvial floodplain. the breaching of levees can also cause a new distributary to form as the water spills over the banks and starts eroding a new path. Use a case study to explain how landforms are interrelated in a low energy environment (LSD)Nile delta. northwesterly winds cause sediment to move eastwards this sediment is then used to form sandy beaches, spits, lagoons, salt marshes and dunes e.g. those at Gamasa these landforms are interrelated because they share the same source of sediment Use a case study to explain how and why a low energy environment changesNile delta. seasonal Nile river discharge is highest in the summer months because a significant amount of the Nile's discharge comes from Ethiopia's summer monsoon rains and so this is when deposition rates are highest and when the river Nile tends to flood and breach its levees so this is when the floodplain (between distributaries) is most fertile. dams the Aswan High Dam was constructed in 1964 before the dam was constructed, the Nile's annual flood deposited 120 million tonnes of silty mud today the sediment yield is negligible, meaning rates of erosion are now higher than of deposition. currently there are concerns over the Grand Ethiopian Renaissance Dam (built from 2011-2020) where Nile water has been diverted to fill the reservoir behind the dam further reducing the volume of water and sediment reaching the delta more dams are proposed so this challenge is likely to worsen over time. sea level rise sea level in the Mediterranean has been rising by 3.2 mm/year since 2012 so climate change is contributing to higher erosion rates along with water extraction for reservoirs, this is causing the delta to recede at 90-150m per year in some places. Use a case study to explain long-term change in a low energy environment (dams)Nile delta. the Aswan High Dam was constructed in 1964 before the dam was constructed, the Nile's annual flood deposited 120 million tonnes of silty mud today the sediment yield is negligible, meaning rates of erosion are now higher than of deposition. currently there are concerns over the Grand Ethiopian Renaissance Dam (built from 2011-2020) where Nile water has been diverted to fill the reservoir behind the dam further reducing the volume of water and sediment reaching the delta more dams are proposed so this challenge is likely to worsen over time. Use a case study to explain short-term change in a low energy environmentNile delta. Nile river discharge is highest in the summer months because a significant amount of the Nile's discharge comes from Ethiopia's summer monsoon rains and so this is when deposition rates are highest and when the river Nile tends to flood and breach its levees so this is when the floodplain (between distributaries) is most fertile. Use a case study to explain long-term change in a low energy environment (sea level rise)Nile delta. sea level in the Mediterranean has been rising by 3.2 mm/year since 2012 so climate change is contributing to higher erosion rates along with water extraction for reservoirs, this is causing the delta to recede at 90-150m per year in some places. Use a case study to explain long-term change in a low energy environmentNile delta. dams the Aswan High Dam was constructed in 1964 before the dam was constructed, the Nile's annual flood deposited 120 million tonnes of silty mud today the sediment yield is negligible, meaning rates of erosion are now higher than of deposition. currently there are concerns over the Grand Ethiopian Renaissance Dam (built from 2011-2020) where Nile water has been diverted to fill the reservoir behind the dam further reducing the volume of water and sediment reaching the delta more dams are proposed so this challenge is likely to worsen over time. sea level rise sea level in the Mediterranean has been rising by 3.2 mm/year since 2012 so climate change is contributing to higher erosion rates along with water extraction for reservoirs, this is causing the delta to recede at 90-150m in some places. Use a case study to explain the unintentional impacts of economic development on the coast (NZ)nearshore dredging along the Mangawhai-Pakiri coastline of NZ for over 70 years from 1994 to 2004 the rate of extraction was 165,000 m3 per year this output of sediment is naturally replaced very slowly with extraction rates at Pakiri Beach exceeding inputs by a factor of 5 therefore the sand supply of dunes, beaches and the sea bed is depleted and the coast retreats Explain eustatic sea level riseeustatic sea level rise is an absolute rise in sea level caused by continental ice caps / sheets melting so more water in oceans and thermal expansion of water, so same amount of water takes up more volume. example the most recent period of eustatic sea level rise is the Flandrian Transgression from 18,000 to 6,000 years ago as sea levels increased by 120m due to a warming climate after the last glacial period. Explain isostatic subsidenceisostatic subsidence is a relative rise in sea level the main cause of which is ice sheets compressing the lithosphere in glacial periods. Explain eustatic sea level falleustatic sea level fall is an absolute fall in sea level, occurring in cooling climates caused by continental ice caps / sheets forming so less water in oceans and thermal contraction of water, so same amount of water takes up less volume. example eg 125,000 years ago sea level was 8m higher than today during the Sangamonian Interglacial global temperatures are now over 2 degs lower so sea level is lower as well. Explain isostatic reboundisostatic rebound is a relative fall in sea level the main cause of which is ice sheets melting, allowing the lithosphere to uplift. Explain the formation of abandoned cliffsabandoned cliffs are cliffs left a few metres inland above the HWM sea level abandoned cliffs are emergent landforms, formed by marine regressions there is eustatic sea level decrease in cooling climates due to continental ice caps / sheets forming and thermal contraction of water sea level can also fall due to isostatic rebound, which may be caused by deglaciation. series sometimes there is a series of terraces and abandoned cliffs as new beaches / cliffs etc form before sea level falls again eg in western Scotland platforms are found at 8, 15, and 30m above sea level. Explain the formation of marine terraces / raised beachesbeaches / shore platforms left a few metres inland above the HWM sea level marine regressions cause emergent landforms to form there is eustatic sea level decrease in cooling climates due to continental ice caps / sheets forming and thermal contraction of water sea level can also fall due to isostatic rebound, which may be caused by deglaciation. series sometimes there is a series of terraces and abandoned cliffs as new beaches / cliffs etc form before sea level falls again eg in western Scotland platforms are found at 8, 15, and 30m above sea level. Explain the influence of geomorphic processes on abandoned cliffsformation marine processes will have shaped the cliff before the sea level fall e.g. erosion (pounding/HA/abrasion) forming wave-cut notches, caves, arches, stacks the cliff profile will have been influenced by the relative rates of erosion, weathering, mass movement and deposition current influence sub-aerial processes continue to influence the cliff profile ie weathering and mass movement likely to be biological weathering as well as freeze-thaw, carbonation, oxidation, landslides all of these cause debris to accumulate at the base of the cliff, so cliff becomes less vertical with no wave action to remove the debris. Explain the influence of geomorphic processes on raised beaches / marine terracesformation marine processes will have shaped the shore platform before the sea level fall shore platforms are erosional landforms left behind as the cliff retreats often they are dissected by abrasion as rocks are dragged across max width 500m as friction causes water to lose energy current now only influenced by sub-aerial processes, mainly weathering weathering more significant due to warmer and wetter conditions particularly biological weathering (limpets and whelks) and carbonation cannot grow any more but could possibly shrink due to mass movement of cliff. future sea level rise means they could become influenced by marine processes again? What is a raised beach?a former shore platform left above the HWM emergent landform What is a marine terrace?more large scale than raised beaches do not necessarily have cliffs above them emergent landforms Give an example of a riarias can be found on the south coasts of Devon and Cornwall e.g. at Kingsbridge and Fowey formed during the Flandrian Transgression Describe the features of riasin the lower course, the entire river and surrounding floodplain may be submerged however in the middle and upper course, the tops of the valley sides remain exposed exposed valley sides are quite gently sloping. in plan view, they tend to be winding, reflecting the original route of the river and valley Explain the influence of geomorphic processes on riasrias are drowned fluvial valleys. before will have originally been influenced by fluvial processes rias retain their original winding route which was caused by fluvial erosion and deposition forming as sea levels rose, deposition increased as rivers had less surplus energy for erosion so rias are typically underlain by alluvial deposits current valley sides influenced by sub-aerial processes

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