Describe how a river erodes its bed and banks. (3 marks) Mark scheme. One mark per valid point
Candidate A
A river erodes materials through a number of different processes, the obvious one is hydraulic action where the sheer force of the water has the potential energy to move material. Another is abrasion which works like a sandpaper scraping away at river banks and bed from small particles in the water. Another is attrition where large particles of rock collide against each other forming smaller particles.
Candidate B
Through abrasion, corrosion and hydraulic action, and attrition. Hydraulic action is the most effective as eddies form the banks which undercut them and causes them to collapse.
Study Figure 1 which is a map and a cross section of the valley of the River Wear near Durham. Describe the incised meander shown in Figure 1 and explain the formation of its landform. (6 marks)
Level 1 (1-4 marks)
Describes the landform from Figure 1 – possible recognition of meanders with steep sides at lower end. More purposeful description at the top end. May begin to explain at top end. One element well done can get 4. Generic meanders max 2
Level 2 (5-6 marks)
Describes the landform and links explanation to description. Explanation is sequential and developed. Appropriate geographical terminology is used.
You can see that the incised meander has a steep sided symmetrical cross section. The relief of the land to either side of the meander is very steep. Both sides are of similar height with the right bank (Y) slightly higher at 74m than the left bank (X) at 58m. The incised meander has occurred due to rejuvenation. A fall in base level caused by eustatic or isostatic change has occurred which has given the river renewed energy that is used for erosion. The river tries to regrade itself back to base level to create a graded profile and so vertical erosion dominates. The river would be sinuous in its lower reaches and the existing meanders would be cut into by abrasion causing rapid downcutting and deepening of the river channel. As Figure 1 shows a symmetrical cross section the rejuvenation must have been rapid, leading to the formation of entrenched meanders as vertical erosion has dominated as there has not been a chance for lateral erosion to occur.
Study Figure 2 which is an extract from a news website about the cause of floods in Pakistan in August 2010. With the help of Figure 2 explain why floods occurred in Pakistan in August 2010. (4 marks)
Mark scheme. One mark per valid point
Rainfall has become more intense with more than half the normal monsoon rain falling in one week. This means that a large amount of precipitation reaches the river channel in a short amount of time so peak discharge above the river’s bankfull capacity. Also levees have been built along the river banks of the Indus. This initially increases bankfull level but in low flow conditions sediment is dropped on the river bed and the channel silts up. This raises the river bed above the level of the flood plain so when the river tops it s banks water cannot naturally drain back into the river and flooding is more severe. Also deforestation has decreased interception, interception storage and evapotranspiration so more water reaches the river channel increasing peak discharge above bankfull capacity so the river floods.
The figure shows a land form resulting from fluvial action. Describe this landform and explain its formation. [7 marks]
This is a meander. I can tell this because it is a sharp bend in a river with a steep bank called a river cliff on the outside of the bend and a beach of pebbles called a point bar on the inside of the bend. The river cliff has some clumps of grass at its base which shows that the bank has collapsed recently. Meanders are formed because rivers rarely flow in a straight line for long. Where there is a bend in the river the fastest flow of water goes on the outside of the bend because of centrifugal force. This water undercuts the bank by the process of hydraulic action, using the weight of the moving water. This process is most effective when the river floods because it has greater velocity and so more kinetic energy to carry out erosion. The clay banks will slump down, but the top of the slump will be held together by the grass roots. Eventually the slumped soil will be washed away and the process starts again. The slowest water is on the inside of the bend. Here the water is so slow that it cannot carry the pebbles and so these are deposited.
NOW SKETCH and ANNOTATE the landform in order to describe it (4 marks)
June 2010. Study Figure 6 which shows birth rates, death rates and total population for Malaysia from 1960 to 2007. To what extent does Malaysia fit the demographic transition model for the time period shown in Figure 6? (6)
Level 2 (5-6 marks)
Clear purposeful description linked to model. Has overview of changes/stages – possibly two present and others not yet gone through. Evidence in support. Appropriate assessment of ‘to what extent’ using evidence.
The birth rate and death rate in 1960 shows that Malaysia would have been in Stage 2 of the DTM because birth rates are still high at that point but death rates are decreasing. Malaysia doesn’t fit the model exactly because they haven’t been through all the stages yet because birth rate is still at 22/000 and the death rate is at 5/000 and by Stage 5 birth rate is meant to be less than death rate. The total population follows the pattern of the model because it has increased dramatically from 1960 to 2007.
Coastal environments and Energy – 15 markers
Describe two or more landforms resulting from coastal erosion (such as headlands and bays, blow holes, arches, stacks, cliff and wave cut platforms) and explain their formation. (15 marks)
Level 2 (7-12 marks)
Description of landforms (2 needed) is more specific and precise. Begins to develop explanation of two landforms – processes defined. Develops answer with clearer, more complete sequence and more appropriate terminology.
Level 3 (13-15 marks)
Clear, purposeful description of landforms (2 needed) – can visualise. Explanation of two landforms – processes explained. Developed answer with clear and complete sequence – links are easy to follow. Appropriate terminology is used.
Coastal erosion causes the emergence of many landforms such as headlands and bays. These are caused by the waves approaching a coastline of hard rocks (limestone) which is more resistant to erosion than soft rocks like clays.
The waves are concordant to the coastline meaning that only the exposes hard rock is eroded. However the hard rock is not impervious to erosion, therefore when the hard rock layer is finally broken through the soft rock layers behind are exposed and are eroded far quicker than the hard rock. The hollowed out parts of the coasts are called bays and the remaining hard rock layer becomes a headland.
Arches, stacks and stumps are other landforms caused by coastal erosion. When a headland is exposed on both sides, waves begin to focus on the headland due to wave refraction. This causes the sides of the headland to be eroded usually via hydraulic action and abrasion mainly. The headland begins to have caves form in the side of them which further hollows out to eventually create an arch. As the arch widens the rock above it loses its support and eventually falls into the sea. This leaves a stack (a pillar of rock) in the sea. Over time the sea erodes the base of the stack (similar to wave cut platforms). Notches appear at the base of the stack which over time topples leaving a stump. Cliffs are subject to sub-aerial processes and combined with the hydraulic action of the waves, the results are similar to that of wave cut platforms.
Discuss the impact(s) of rising sea levels on coastal environments. (15 marks)
Mark scheme
Level 2 (7-12 marks)
Description of impact/s is more specific and precise. Begins to target content to purpose. Begins to consider impact in an analytical way. Focus is on impact/s and there is some engagement in debate. Some support is present in an organised account.
Level 3 (13-15 marks)
Description of impact/s is specific and precise. Clearly considers impact in an analytical way. Impact is to the fore and there is purposeful engagement in debate. Support is present. An organised account that is purposeful in responding to the question.
The rising sea levels by the process of eustatic rejuvenation which can be melting glaciers which increase the sea water’s volume, causing it to rise relative to the land.
The impact on the coast is a variety of landforms. First, submergent landforms, where the base level rises relative to the land. For example Rias, which are submerged river valleys and have gentle valley slopes and a wide river channel. An example of this is Kingsbridge estuary in Devon, now a popular sailing point. Another submergent landform is a fiord, which are submerged glacial valleys and the water in them is often the glacier which created the crater in the land. They have sharply steep sides and look much like a wide lagoon. An example is the Geirangerfjord in Norway.
As these happened so long ago, man has evolved with them and using them for our own uses, but had that happened today the impact on our lives would be catastrophic. The British coast is already experiencing positive eustatic change which has increased the erosion of our cliffs as the sea level is rising above the natural barrier of the beach – for example weaker rock such as Mappleton’s boulder clay is eroding at 2m a year and has already lost 32 villages in the documented life of man. As coastal flooding will continue due to global warming, important coastal cities – our home environment – such as New Orleans, Cairo, London and Shanghai may be lost. This will impact world politics, economy and resources – for example the Nile delta relies upon irrigation channels from the coast and could lose their cotton trade – nearly half of their income.
Conclusively, eustatic change has always occurred and as a sea bound island, Great Britain needs to act against these negative impacts – as we used to be connected to the Netherlands and France and eventually we could end up as a collection of landforms.
But it is also important to see the impact on the environment as wildlife habitats are being threatened such as saltmarsh, home to the Redshank. Therefore as humans, we greatly increase the global warming threat, it is important to foresee the impacts we will commit on ourselves and the environment around us.
To what extent does renewable energy provide the potential for sustainable energy supply and consumption? (15 marks)
Level 2 (7-12 marks)
Clearly describes renewable energy and begins to link to sustainability. Likely to be one-sided – and see all the pluses of renewable. Intermittent support. Tentative/implicit assessment of ‘to what extent’
Level 3 (13-15 marks)
Describes renewable energy in detail and links to sustainability. Will see some negatives as well as pluses of renewable or will consider alternative resources such as nuclear. Support is given throughout. Clear, purposeful and explicit of ‘to what extent’.
At current levels of production, renewable energy sources cannot fulfil global energy needs as it is not widespread or efficient enough. For example it would take over 7000 wind turbines to replace a single power station. It is therefore not realistic at current levels to begin phasing out non-renewable fuel types such as oil and coal.
However its potential for generating power is enormous. Norway generates 90% of its power needs through renewable HEP and can often export power showing that in some regions it is sustainable. New technologies are being developed for example undersea tidal turbines off the Orkney Islands which would be entirely sustainable as the tide will never cease to provide energy. However critics argue that they are not as sustainable as they seem as they could prove a threat to local sea life such as basking sharks.
Renewable sources of power such as the sun also have huge as yet untapped entirely sustainable power reserves. The sun generates the power of billions of nuclear power stations which future technology will harvest efficiently.
Technically non-renewable sources such as nuclear power also have potential for sustainable energy supply as long as waste is disposed of in a sensible manner. Nuclear waste has a half life of thousands of years as it would be unsustainable to dispose of this responsibly.
To summarise I think that in the future renewable energy sources will provide mankind with the energy it needs provided that the price is low enough that all countries can invest in it. The potential is huge but current technologies such as wind turbines or tidal barrages are not nearly efficient enough to end our reliance on non-renewable energy sources such as coal, oil and natural gas.
7 (c) Discuss advantages and disadvantages of two contrasting approaches to managing
energy. (15)
Level 1 (1-6 marks)
Describes at least one contrasting random approach to managing energy. Points made are simple and in a sequence.
Level 2 (7-12 marks)
Begins to target information to purpose in an ordered response. Begins to consider advantages and disadvantages and to discuss contrasts. Begins to debate/comment. Intermittent support.
Level 3 (13-15 marks)
Clear, purposeful summary of advantages and disadvantages. Contrasts are drawn out in a discursive answer. A purposeful discussion, may comment. Support is given throughout.
In Burkina Faso fuelwood is being used faster than it is being replenished and 90% of Burkina Faso’s population depend on fuelwood, therefore this is a big problem. To try and manage the energy and conserve energy they have developed a solar cooker in which they use energy from the sun to power cookers for making food. The advantages of this approach are that solar power is renewable, it is a clean source that has a continuous supply. It is inexpensive as it is fuelled by the sun and solar energy will always be able to be provided. This will reduce the need and dependency on fuelwood. However the disadvantage of this approach is that solar power is only best in the summer months and will only be able to be used when it is sunny to provide fuel for the cookers. Therefore you cannot always depend on solar power.
The UK gave developed a UK sustainable energy plan to try and conserve the energy we are using in our homes for transport and for economy. The UK government have developed a ‘feed in tariff’ scheme where the population get paid for making their own energy such as in the home through the use of solar panels on the roofs, wind turbines to try and reduce the energy we use. They are also developing ‘smart’ electricity monitors which allow people to view how much electricity they are using in real time. These methods are beneficial as people are reducing the amount of electricity they use in their homes. The disadvantage of these is that the solar panels and wind turbines are initially expensive to install. The UK are also developing a bike hire scheme in London in which 400 docking stations around Zone 1 in London people are able to pick up and use bikes instead of using energy of public transport and vehicles. This is beneficial because it reduces the pollution produced from vehicles and transport and helps people to become healthier. The disadvantage is that there is a lack of safety when riding bikes, for example 10 cyclists have already died this year in London and it is only Zone 1 in London and there are no docking stations near train stations which is not beneficial for commuters. Another way in which the UK are managing energy is through developing energy efficient businesses such as Sainsburys in Dartmouth which have cut electricity use by 50% through use of two wind turbines which fuel the checkouts and a wave shaped roof which flushes the lavatories. This is beneficial as it saves energy and electricity use.
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