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Description
Flashcards by Fxxxxxx Hxxxx Rxxxxx, updated more than 1 year ago
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Created by Fxxxxxx Hxxxx Rxxxxx
over 5 years ago
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| Question | Answer |
| Describe the diagram for interlocking spurs |
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| Describe the formation of interlocking spurs | In the upper course there is more vertical erosion. The river cuts down into the valley. If there are areas of hard rock which are harder to erode, the river will bend around it. This creates interlocking spurs of land which link together like the teeth of a zip |
| Describe the diagram for waterfalls | |
| Describe the formation of waterfalls | A waterfall is a sudden drop along the river course. It forms when there are horizontal bands of hard rock (limestone) positioned over exposed, more soft and less resistant rocks (sandstone). The soft rock is eroded quicker than the hard rock and this causes the hard rock to overhang and the soft rock to undercut. This is because of erosion such as hydraulic action (the sheer power of the waves crashing against the soft rock) and abrasion (rocks being thrown at the soft rock). Since the hard rock overhangs, it causes water to fall down and this creates a plunge pool. The plunge pool gets larger when there is more erosion (hydraulic action and abrasion) and the soft rock continues to undercut, making the hard rock unstable and it collapses as it is unable to support itself. This causes the waterfall to retreat upstream and this process is repeated and continues forming a steep sided river gorge |
| Describe the diagram for a meander | |
| Describe the formation of a meander and oxbow lake | A meander is a bend in a river’s course. Due to meanders being located in the middle course, the river will have a higher volume of water. Lateral erosion starts to widen the river. As the river goes around the bend, most of the water is pushed towards the outside causing erosion (hydraulic action and abrasion) as the velocity is higher on the outside bend. A river cliff is formed due to erosion. However, the velocity on the inside is slower and the water therefore deposits material as the water loses energy. A gentle slope is formed and the buildup of material and sediments form a slip-off slope. Erosion will over time cause the neck of the meander to narrow and this causes the meander to become closer together. When there is a very high discharge, the river cuts through the neck taking a new, shorter and quicker route. Deposition will cut off the original meander leaving a horseshoe shaped oxbow lake that is isolated. Due to vegetation, the oxbow lake can eventually dry up |
| Describe the diagram for floodplains |
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| Describe the formation of floodplains and levees | Floodplains are flat areas of land on either side of a river and lateral erosion widens the sides and removes any interlocking spurs. During floods, water bursts out of the banks and due to deposition, the river deposits the larger materials first and then the smaller materials later along in the river. Due to frequent flooding, the levees get higher and higher Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs |
| Define flooding | When a river overflows its banks causing it to flood and water to spread out onto nearby land |
| What are the physical causes of flooding | Intense and prolonged rainfall prevents soil infiltration Steep sided river valleys and the gradient The geology of rocks, snow melt and droughts |
| What are the human causes of flooding | Deforestation Flood management Overgrazing of farm animals Urbainsation Agriculture Industry |
| Explain how urbanisation leads to flooding | Causes an increase in the construction of rocks which are impermeable so water flows into the rivers increasing the volume of water that the river holds. Increased demand for housing has lead to houses being built on floodplains and this changes the natural landscape. Rivers may also be channelised or made to flow underground to make room for urban developments. If this happens, erosion and deposition cannot take place |
| Explain how industry leads to flooding | A big user of water and so can reduce the amount of water in rivers leading to less erosion. Industrial processes can pollute rivers if chemicals or wate are spilled or dumped into them. This can destroy plants and animals and change the natural landscape |
| Explain how deforestation leads to flooding | Trees need to be cut and this means water reaches rivers quicker as there are less trees to intercept the rainfall and help reduce surface runoff. Abstracting water for irrigation also reduced the flow and velocity of a river so deposition occurs rather than erosion. Ploughing fields up and down a slope can increase the amount of sediment in rivers and increases deposition |
| What are the social effects of flooding | Death, diseases and injuries Damage to property, insurance claims and disruption to transport |
| What are the environmental effects of flooding | Landslides, soil erosion and loss of natural habitats Contamination of water supplies and loss of crops |
| Define hard engineering | Hard engineering means building artificial defences and physically changing the landscape. It is effective but expensive |
| Define soft engineering | Soft engineering takes a more natural approach and is more environmentally sustainable. It is cheaper but less effective |
| Define dams and reservoirs | Dams and reservoirs traps water which builds up behind it, forming a reservoir |
| What are the advantages of dams | Water can be released in a controlled way which produces hydroelectric power by passing the water through the turbines It also creates work and is attracts tourists and provides a local water supply and can be used for water sports |
| What are the disadvantages of dams | Very expensive and can cause displacement of people and they are not compensated Lakes may suffer from the growth of algae and habitats are flooded often leading to rotten vegetation and this releases methane which is a greenhouse gas |
| Define channelisation | Channelisation is when a river is straightened and deepened. |
| What are the advantages of channelisation | More water can be held in the channel and this reduces flood risks as water moves downstream quicker and away from settlements |
| What are the disadvantages of channelisation | Dredging needs to be done frequently and speeding up the river increases flood risks downstream |
| Define flood plain zoning | Flood plain zoning is when the government allocates certain areas of the land for specific purposes according to flood risk levels |
| What are the advantages of flood plain zoning | More expensive buildings are further away from the river so less damage is caused, leading to fewer insurance claims There is open space for leisure which can be flooded and this is cheap |
| What are the disadvantages of fllod plain zoning | Not always possible to change existing land uses and there may be development restrictions |
| Define washlands | Washlands are areas of a floodplain that are allowed to flood |
| What are the advantages of washlands | There is a safe place for water to go and helps slow down water The soil structure is restored (replenished) and allows new habitats |
| What are the disadvantages of washlands | May limit the use of the land such as for recreation and reduces the land available for farming |
| Describe the Bradshaw model |
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Bradshaw 1 (image/gif)
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