Karteikarten
River processes and land forms
Karten in diesem Stapel (87)
- 1How much water on Earth is fresh water?4.04%
- 2Where is that fresh water contained?Glaciers and polar ice contain 73.8%
Groundwater contains 26%
Surface stores (lakes and rivers) contain 0.22%
The atmosphere contains 0.0024%
The biosphere contains 0.0025% - 3What is evaporation?Water turns from water droplets into water vapour.
- 4What is Throughflow?Water flows horizontally through the soil into the river.
- 5What is surface run-off (also called overland flow)?Water flows horizontally over the land into the river.
- 6What is transpiration?Water vapour is released through the stomata (pores) in the leaves.
- 7What is percolation?Water flows vertically through the soil and rocks.
- 8What is interception?Water is stored on the leaves and branches of the vegetation.
- 9What is groundwater flow?Water flows horizontally through the rock into the river.
- 10What is infiltration?Water seeps into the ground.
- 11What is the water table?It is the level at which saturation occurs.
- 12What is saturation in the ground?It is when the soil or rock is full of moisture.
- 13Explain the process of evaporation?The energy from the sun heats up the water and turns the liquid water into water vapour; this is evaporation. When the water evaporates, it becomes an invisible gas in the atmosphere. Evaporation takes place all over the world but especially in the oceans and lakes where there is lots of water.
- 14What is the process of condensation?As the water vapour rises, it cools off and condenses into water droplets. If the water vapour becomes extremely cold, it will form ice crystals instead of water droplets. As the water droplets or ice crystals grow bigger and more numerous, they form clouds.
- 15What is the process of precipitation?If water droplets or ice crystals become too heavy, they can't stay in the air. They precipitate as snow. Sometimes the rain freezes before it hits the Earth and precipitates as hail.
- 16What is the process of run-off?This precipitation gathers into streams and rivers that flow down to the lakes and oceans. This is called run-off. Not all of the water makes it back to the oceans and lakes right away. Some of it is used by animals and plants. Some is frozen into glaciers. Eventually, the animals and plants breathe the water out and the glaciers melt, releasing the water back into the water cycle.
- 17What is the catchment area/drainage basin?The area from which the river gets its water.
- 18What is watershed?It is the upland area separating one catchment area or drainage basin from another.
- 19What is the source of a river?This is where the river begins to flow. The source of a river could be a glacier, lake, spring or saturated land.
- 20What is a tributary(ies)?A smaller river that joins/flows into the main river.
- 21What is the confluence of a river?This is the point when the tributary joins the larger river.
- 22What is the mouth of a river?It is the point were the river meets the sea. There are two types of river mouths; Estuary(ies) and Delta.
- 23What is discharge?How much rain goes into the river. Volume of water passing a given point on a river in a given time.
- 24What does a flood hydrograph compare?Rainfall in mm.
Discharge in cumecs. - 25What is 'lagtime'?The time between the peak rainfall and the peak discharge.
- 26What are the three ways that water from a rainstorm gets into the river?Throughflow.
Surface run-off.
Precipitation falling directly into the river. - 27How will the factor, precipitation, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?High drainage density = Heavy and prolonged rainfall. Heavy snowfall and suddenly rising temperatures.
Low drainage density = gentle or no rain. - 28How will the factor of, Relief, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?high drainage density = Faster run-off on steeper slopes.
Low drainage density = slower run-off on more gentle slopes. - 29How will the factor of, rock type, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?High drainage density = surface run-off on impermeable rocks.
Low drainage density = throughflow and groundwater flow as rainfall infiltrates into permeable (porous) rock. - 30How will the factor of, soil, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?High drainage density = Very thin soil, less infiltration.
Low drainage density = Deeper soil, more infiltration. - 31How will the factor of, natural vegetation, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?High drainage density = Thin grass and moorland, less interception.
Low drainage density = Forest, most interception, roots delay throughflow and absorb moisture. Evapotranspiration reduces chances of water reaching river. - 32How will the factor of, land use, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?High drainage density = Urbanisation; increased tarmac (impermeable layer) and drains (increased run-off). Arable land exposes more soil.
Low drainage density = Rural area with little tarmac, concrete or drains. Trees, crops and arable farming increase interception. - 33How will the factor of, use of river, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?High drainage density = limited use.
Low drainage density = Water extracted for industry, domestic use and irrigation. Dam built to store water. - 34How will the factor of, drainage density, effect a drainage basin with a high drainage density and a drainage basin with a low drainage density?Higher density means more streams to collect water quickly.
Lower density; fewer streams to collect water. - 35Will the lagtime be longer or shorter on a higher density drainage basin in a rainstorm?The lagtime will be shorter due to far more water in the streams than in a low drainage density which lagtime will be longer because there is more interception and less water in streams.
- 36Why is there a flood risk after a long period of heavy rainfall?Because the ground becomes saturated and so therefore there will be less infiltration and more surface run-off instead, this causes river levels to rise.
- 37Why is there a high flood risk after a summer thunderstorm?Because the ground becomes too hard for the rain to infiltrate, and the surface run-off causes river levels to rise rapidly causing a flash flood.
- 38Why is there a high flood risk when a heavy snowfall follows a few days when temperatures remained below freezing?Because water is held in storage so when the temperatures rise there will be a release of water, and if the ground is frozen then the water cannot infiltrate.
- 39Why is there a high flood risk in an area with an impermeable underlying rock?Because the water cannot infiltrate, causing lots of surface run-off which causes the river to rise.
- 40Why is there a high flood risk in a river basin that has just been deforested?Because there is nothing to intercept the rainfall and this means more water can reach the river.
- 41Explain the 4 ways that a tree intercepts precipitation.1) Leaves intercept the rainfall and so delay run-off to the river.
2) Evapotranspiration reduces the amount of water reaching the river.
3) Roots delay throughflow of water to the river.
4) Roots take up water and so reduce the amount entering the river. - 42Why is the Mississippi a high flood risk river?Because it's catchment area covers 41 states with over 100 tributaries.
- 43What caused the Mississippi flood in 1993?Heavy rain in April meant ground was saturated and then thunderstorms throughout June caused rapid surface run-off and flash floods, one thunderstorm gave 180mm of rain in a few hours. This all caused the flood in 1993.
- 44What were the immediate effects of the Mississippi flooding?Took several months for water to drain off land; ground to wet for planting crops.
Contents of houses and factories, even if not buildings themselves, were ruined.
Cleaning-up operations took months, and where sewage had been washed into waterways, there was a threat of disease. Stagnant water = mosquitos and rats; insurance claims = high and numerous. (43 died, 50000 evacuated). - 45What were some of the long term effects of the Mississippi flood?People have to permanently move out of their homes/spend a lot of money on rebuilding home.
People without jobs.
Infrastructure effected, e.g. roads blocked off = transport effected; loss of river for transport.
Lots of money spent to try and rebuild towns and cities. - 46How had human activities unintentionally increased the flood risk on the Mississippi?New levees and dams etc. had been built; store more water but when these flood defences have been breached then more water will be able to flood surrounding area. By reducing flood risk we could unintentionally making effects of flooding worse.
- 47Which four methods have been used to reduce the flood risk on the Mississippi since 1927?Building dams + reservoirs on Missouri river; could control water that went downstream in the river, reducing volume of water during flooding.
Afforestation = trees delay run-off; reduce amount of water reaching river.
Diversionary spill ways; these are overflow channels - can take surplus water during times of flood.
Making course straighter + shorter - get rid of flood water faster; achieved by cutting through narrow necks of large meanders. - 48Which of the methods mentioned on the previous flashcard is the cheapest and why?Afforestation, because trees are cheaper to buy and labour to plant them will be cheaper.
- 49Which of the methods mentioned on the previous flashcard is the most expensive and why?Dams and reservoirs, because they are a lot bigger to build and the materials needed to build it will cost more.
- 50Which of the methods mentioned on the previous flashcard would be the most successful in reducing the flood risk and why?Dams and reservoirs, because you can control the amount of water in the river at a certain time.
- 51Why is it harder to reduce the flood risk LEDCs than in MEDCs?Because it often needs considerable amounts of money and high levels of technology to reduce flood risks, so LEDCs do not have the money or technology to do this.
- 52What defences were built after the river Eden flooded in 2005?Clay covered embankments were built and reinforced concrete walls were built along the river to protect homes and businesses.
Flood defences were built around the flood plains to prevent main city being flooded.
Self-closing flood barriers and flood walls were built. - 53Why is the lagtime shorter in urban areas?Urban area.
Impermeable surfaces and storm drains.
Reduced infiltration.
Increases surface run off.
Shorter lagtime.
River likely to flood. - 54Why is there a shorter lag time when the land is saturated?Saturated land.
Reduced infiltration.
Increased surface run-off.
Shorter lagtime. - 55Why is there a short lagtime when there has been deforestation?Deforestation.
Reduced interception.
Increase of surface run-off.
Shorter lagtime. - 56What are the short term benefits and problems with building flood defences like in Shrewsbury and Bewdly?Benefits = Make river capacity bigger; less chance of flooding. Prevents immediate flooding.
Problems = Takes longer for flood water to drain away; they are blocking water getting back to river; costs a lot to install. Floods next village along. - 57What are the long term benefits and problems with building flood defences like in Shrewsbury and Bewdly?Benefits = Protects property from flooding; saves money. Stops businesses being disrupted; they can carry on their business during times of flooding.
Problems = Causes visual pollution. May not last forever. - 58Who might agree/disagree with building flood defences?Agree = Residents.
Disagree = River scientists. - 59What are the short term benefits and problems with restoring bogs and moorland in mid-wales by blocking drains?Benefits = Forces water to soak back into soil; slows down overland flow.
Problems = Blocks drains and means nobody can go there. - 60What are the long term benefits and problems with restoring bogs and moorland in mid-wales by blocking drains?Benefits = Improve the moorland ecosystem. Help to protect rare birds or prey like the merlin and hen harrier.
Problems = Cannot use it as farmland. - 61Who might agree/disagree with restoring bogs and moorland by blocking drains?Agree = RSPB.
Disagree = Framers. Housing ministers. - 62What are the short term benefits and problems by having tighter controls on building on flood plains and paving over gardens?Benefits = More infiltration can take place, because there are less impermeable surfaces, so reduced overland flow = less water in river.
Problems = People might not want to, because they like their garden now, or like their house were it is. - 63What are the long term benefits and problems by having tighter controls on building on flood plains and paving over gardens?Benefits = less houses will be flooded; flooding might not be as bad due to more permeable surfaces.
Problems = Less houses being built; not everyone can get houses; houses more expensive. Concrete businesses lose customers. - 64Who might agree/disagree with the solution of tightening controls on building on flood plains and paving over gardens?Agree = Housing ministers. Planners.
Disagree = Residents. Housing ministers. - 65What are the short term benefits and problems with allowing rivers to flow naturally and spill over onto the flood plain?Benefits = Less homes/businesses flooded. Less money spent on flood defences.
Problems = Less places to build homes on; more chance of homes being flooded that are on the floodplains, buildings have to be knocked down. - 66What are the long term benefits and problems with allowing rivers to flow naturally and spill over onto the flood plain?Benefits = Future flooding happens away from built up area.
Problems = Less places to build on, if it got turned into farm land, farmers cannot use their land, costing them more. - 67Who might agree/disagree with the solution of allowing rivers to flow naturally and spill over onto the flood plains?Agree = River scientists. Housing ministers.
Disagree = Farmers. Residents. - 68What are the two directions of erosion called?Vertical erosion (downwards).
Lateral erosion (sideways). - 69Which type of erosion, lateral or vertical erosion, becomes less important as the river gets further down stream?Vertical erosion becomes less important and lateral erosion takes place.
- 70What are the four different ways that the river erodes by?Attrition.
Hydraulic action.
Corrasion (abrasion).
Corrosion. - 71What is attrition?It is when boulders and other material, which are transported along the bed of the river, collide and break up into smaller pieces. This is more likely to occur when rivers are still flowing in highland areas.
- 72What is hydraulic action?It is when the sheer force of the river dislodges particles from the river's banks and bed.
- 73What is corrasion, when does it occur and why?It occurs when smaller material, carried in suspension, rubs against the banks of the river. This process is more likely in lowland areas by which time material will have been broken up small enough to be carried in suspension. River banks are worn away by a sand-papering action which is also called abrasion.
- 74What is corrosion?It is when acids in the river dissolve rocks, such as limestone, which forms the banks and bed. This can occur at any point of the river's course.
- 75What are the four processes of transportation?Traction.
Saltation.
Suspension.
Solution. - 76What is traction?Rolling stones along the bed. ( this needs the most energy).
- 77What is saltation?Sand-sized particles bounce along the bed in a 'leap-frog' movement.
- 78What is suspension?Silt and clay-sized particles are carried within the water flow.
- 79What is solution?Some minerals dissolve in the water. (This needs the least energy).
- 80Explain how a waterfall is formed.It is formed because the hard resistant rock ('cap rock') does not corrode, but the soft rock underneath does corrode. So from the hydraulic action (sheer force of water attacking cracks in the rock) of the waterfall and corrasion (rocks in water rubbing against bed and banks) as the water falls over the lip vertical erosion takes place. After a while a plunge pool is formed by the force of water hitting soft rock below and deepened by rocks rubbing against the bed and sides (abrasion). Eventually the overhang collapses due to lack of support from the soft rock. So gradually the waterfall retreats upstream leaving a steep-sided gorge.
- 81How does a meander in a river form? (part of stages to an oxbow lake forming)The river flows over flatter land and slows down, then when the water in the river flows fastest around the outside bend, lateral erosion takes place due to hydraulic action, which then leads to the water eroding a bend in the landscape called a river cliff; this then creates a meander.
- 82What is deposition, and where does it happen most? (part of stages to an oxbow lake forming)Is when the river carries sediment and drops the load somewhere else, this happens when the river loses energy, and because there is less energy on the inside of the meander, the sediment is deposited here, creating a slip-off slope.
- 83How does an oxbow lake form (previous two flashcards lead to formation of the lake)?The neck of the meander gets narrower, creating a swans neck, so when the river floods it cuts through the neck of the meander, creating a new course for the river. The deposition left behind, cuts of meander from the new course of the river, creating an oxbow lake.
- 84How does a flood plain happen?When the river has a high volume of water flowing down it, so the river has lots of energy so it transports large amounts of material in suspension. When the river overflows its banks, it spreads out across the surrounding flat land. This means there is a sudden increase in friction which reduces the waters energy/speed and fine silt is deposited. Each time river floods, more and more silt is deposited and a flat floodplain is formed.
- 85How do natural levees form?When the river has a high volume of water flowing down it, so the river has lots of energy so it transports large amounts of material in suspension. When the river overflows its banks, it spreads out across the surrounding flat land. This means there is a sudden increase in friction which reduces the waters energy/speed and the heaviest material is dropped first buy deposition, this overtime creates a natural levee/embankment, on the river banks. Sometimes these natural levees/embankments are artificially strengthened to act as flood banks/barriers.
- 86What happens to large rivers when they reach the sea? (part of stages to forming a delta)As large rivers reach the sea they have the energy to carry huge amounts of fine material in suspension. On reaching the sea the river current may suddenly be reduced, losing energy and allowing the material to be deposited. Sometimes the deposition occurs in the main channel blocking it. The river then has to divide into a series of smaller channels called distributaries, in order to reach sea.
- 87How are deltas formed and where? (continued explanation from previous flashcard).Over a period of time the silt and sand may build upwards and outwards to form a delta. Deltas are only likely to form where the amount of material bought down by the river is too great for sea currents to remove it or in seas that are virtually tideless. Deltas can also form when a river flows into the gentle waters of a lake.
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- GCSE Geography (Theme 2) Karteikarten am River processes and land forms, erstellt von Rebecca Smith am 27/02/2017.
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