AQA AS Geography
Revision Day for Isle of Man students
May 2013
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. (3)
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. (2)
(a)i. Outline the causes of rejuvenation. (2 marks)
Mark scheme. One mark per valid point
Candidate B
Either the sea level falls in relation to the land or the land rise in relation to the sea. (2)
(b)ii. 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 ahs 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. (6)
(c)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. (4)
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 a landform to describe it:
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. (5)
The 15 markers
Assess the relative importance of physical and human factors in the cause of flooding. (15 marks)
Level 2 (7-12 marks)
Seeks to explain how physical factors and/or people cause flooding – links to runoff and infiltration are present. There may be imbalance between the two causes. May relate to case studies/illustrate points made. Appropriate terminology is used. Tentative/implicit assessment of relative importance
Level 3 (13-15 marks)
Explains clearly how physical factors and people cause flooding – clearly appreciates sequence of events set in motion linked to drainage basin hydrological cycle. There will be balance between the two aspects. May use case studies/detail and purpose in exemplification. Specific terminology is used throughout. Explicit assessment of relative importance – probably suggesting overall importance of physical factors, but made worse by role people play.
Certain human activities can have a great impact on river flooding. In built up urbanised areas there are often rivers close by. The build up of impermeable surfaces like concrete pavements means that when precipitation occurs infiltration is not possible and rain water flows straight to the river channel as surface runoff, increasing lag time and river discharge – effectively causing a river to flood.
Drainage systems also don’t help as a human cause. Water is carried straight to the river via drains instead of gradually getting there via baseflow. An example of this was found in Carlisle in 2005 when 25% of the flooding was caused by Carlisle’s drainage system.
Also human causes include deforestation – by cutting down trees, vegetation storage and interception is prevented meaning water reaches the river more quickly. This human cause can be linked to a physical cause. If a river channel is near to an area of naturally sparse vegetation the same effect occurs. Landscape is also a major physical cause. Low lying flat lands like south Asia – Bangladesh and Nepal for example – suffer badly from lack of drainage – no hills to drain off. Monsoon season is also a major flood cause here as in monsoon season much rain falls on these unsuitable drainage basins. In 2007 Bangladesh suffered some of the worst river floods in years/ 169.5mm of rain fell over 36 hours and this meant the ground was saturated and so excess water flowed straight to the river Ganges as surface run off.
Overall the importance varies in that human causes can be minimalised or prevented so physical causes seem to be the main problem. (14)
‘Soft engineering is a better river flood management strategy than hard engineering’. Discuss this view. (15 marks)
Level 2 (7-12 marks)
Describes strategies and begins to discuss why soft engineering strategies are better (or an alternative option). Uses strategies to illustrate points – will illustrate one aspect only or with imbalance eg advantages of soft engineering may be discussed with no reference to hard engineering. Case study material is used in a descriptive way. Appropriate terminology is used
Level 3 (13-15 marks)
Clear purposeful discussion that seeks to put a case for/against soft engineering or is aware of the complementary nature of the strategies. Strategies are effectively used to illustrate concepts. Case studies are used to make points. Specific terminology is used throughout.
Soft engineering schemes cost a lot less money to construct. For example, afforestation on the River Quaggy cost around £10000 whereas the hard engineering project whereas the hard engineering project, the Three Gorges Dam, cost around £25 billion to construct. Due to these costs, countries who do not have much money will find soft engineering schemes to be more cost effective. However it can be argued that soft engineering is not as effective as hard engineering. It does not provide the amount of control over a river as hard engineering. On the other hand soft engineering is more environmentally friendly. For example at the River Quaggy, more habitats were created through afforestation and habitats were also kept safe through wetland conservation. The Three Gorges dam destroyed 1000’s of green areas, disrupting habitats. It also led to the white flag dolphin losing its habitat and becoming an endangered species.
However, soft engineering schemes do not provide anything extra to the people. The Three Gorges dam produced hydroelectric power that was enough to power the whole of central and eastern China, including Shanghai which has a population of about 13 million people. However it did cause 1.3 million people to move house and also left 14 million people homeless.
The soft engineering scheme at the Quaggy did not provide anything extra to the community but used simple methods such as contour ploughing to reduce surface runoff which decreases likelihood of a flood and didn’t cause any people to move.
In conclusion I think that hard engineering strategies are more effective at flood management as long as the country can afford it. For poor countries soft engineering schemes will be a better river flood management process. (14)
With reference to one case study, discuss the impact of flooding on people and the environment. (15 marks)
Level 2 (7-12 marks)
Description of effects of floods is more specific and precise. Some reference to people and the environment – but may be very imbalanced. Information relates to case study – rings true – some support. Begins to discuss and to consider aspects that cause debate or gives comment – may be tentative/implicit
Level 3 (13-15 marks)
Description of effects of floods is specific and precise. Some reference to people and environment – greater balance. Specific reference to case study in support of points. Discusses aspects that cause debate and offers comment that is purposeful.
Flooding affects people directly if their homes are affected. People lose their personal possessions which then causes grief. They may also be made homeless as their homes are either destroyed or damaged by the floodwaters. 10.5 million people were displaced and made homeless by the 2007 Bangladesh floods.
Another direct impact on people is that they may suffer from diseases which are carried by the water such as cholera. This is much more apparent in countries such as Bangladesh where medical supplies are limited. However it may also occur in the UK. Another direct effect is on deaths. In Bangladesh 959 people died either from disease or directly from the floods.
An impact on the environment would be a contaminated water supply which could also affect people as it increase the risk of disease. Another environmental impact would be the damage caused to the infrastructure such as transport and communications networks. In Bangladesh the airport was flooded and this meant planes could not fly to and from the country very easily. Damage is also caused to bridges and roads. This affects people because they may not be able to move to safer area away from the flooding. Aid and rescue services may not be able to reach people to help them with the effects of the flood. £60 million worth of aid was given to Bangladesh to help with the floods but due to the environmental effects of the flood this aid may not have reached the people who needed it most. Overall I think that the impact of flooding on people is far greater than the impact on the environment. Also the impact on the environment then indirectly affects people too. (14)
‘An ageing population can bring economic, political and social advantages and disadvantages.’ Discuss this view. (15 marks)
Level 2 (7-12 marks)
Describes advantages and/or disadvantages. 2 categories considered. Points are supported in places. Begins to discuss and make occasional comment
Level 3 (13-15 marks)
Describes clearly advantages and/or disadvantages, in greater balance. 3 categories considered, but may be imbalanced. Exemplification is used to support answers. Discusses and makes clear pertinent comment.
An ageing population means that there is a high proportion of elderly people. In the UK this is happening and this has caused a growth in the ‘grey pound’. Retirees demand services such as leisure and tourism and this has allowed these industries to develop which boots economic development. However economic development is also decreased by an ageing population. Due to low birth rates not many young people enter the workforce and so the size of the workforce shrinks as more and more people retire. This means there is a shortage of workers and economic development slows down. The government also receives less tax revenue from the decreased working population. This makes it very hard to pay pensions for those who are retired.
A political impact to try and cope with an ageing population would be that the government may increase taxes on the working population to pay the pensions. This could affect economic development as people would have lower incomes. The government may also increase the retirement age which could increase the size of the working population but would mean people would have to work for longer. A political advantage of an ageing population would be the ‘grey vote’. This is very important to political parties as the elderly make up a large proportion of the population.
There would be less pressure on resources due to a low birth rate and slower growth. So there would be less need for schools and childcare facilities. However, there would be more need for sheltered accommodation, retirement homes and carers. Government funds may also need to be directed into health care for age related diseases such as dementia. This would mean there would be less provision for healthcare. The government may try to encourage births and immigration which would increase the size of the working population.
Overall I think that the disadvantages of an ageing population outweigh the benefits. This is because if the population continues to age, the problems will get worse, for example the working population would continue to decrease in size and tax revenues would decrease. As tax revenue decrease governments would find it increasingly difficult to fund the provision of health care and pay pensions. (14)
Using examples, summarise the differences in characteristics in two of the following areas, and suggest how they may impact on social welfare for each area:
inner city area, suburban area, rural urban fringe and an area of rural settlement.
[15 marks]
Inner City and Rural settlement
In the inner city of Fishwick in Preston there is usually 19th century housing such as terraces with no gardens and no driveways. This is in contrast to rural areas such as Longton where the housing is mainly detached homes with large gardens and driveways meaning that people’s cars are safer and so there may be less crime. In addition to this, the ethnicity of people varies. In the inner city there is more ethnic minorities eg in Fishwick only 67% of the population are ‘white’ whereas in Longton 92% are ‘white’. This may mean that in areas such as Fishwick there is less social cohesion as there are many different ethnic groups who all want to instil their own values. However, it may be more of an issue in rural areas as the minority group may want to open a store eg a Caribbean food shop which is less common and may be less accepted there.