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AS and A Level: Hydrology & Fluvial Geomorphology
Meet our team of inspirational teachers
Five things you need to understand about hydrology and fluvial geomorphology
- 1 Make sure you understand the concept of systems, and the difference between a closed system (the global hydrological cycle) and an open system (the drainage basin)
- 2 Learn the correct definitions of all the specialist terms (eg percolation, throughflow, hydraulic radius, etc.
- 3 Learn a case study which shows how the theory relates to an actual example of a real river basin.
- 4 Remember that rivers are not static – they are affected in the short term by weather patterns and human activity and in the long term by changes in climate, tectonic processes and sea levels.
- 5 Pay attention to scale: for example British rivers (and British floods) are tiny compared to the great rivers (and great floods) experienced in other parts of the world.
Common errors in hydrology and fluvial geomorphology essays
- 1 Although rivers near their source often look like they are flowing quickly, and rivers near their mouth look like they are flowing slowly, river velocity increases downstream. This is because there is more turbulence upstream (due to friction) and rivers flow more efficiently as they get further downstream (as friction reduces).
- 2 Infiltration is the movement of water into the soil. Percolation is the movement of water into the underlying rock. Students often confuse these two terms.
- 3 Landforms are often referred to as landforms of erosion (eg waterfalls) or landforms of deposition (eg deltas). However, it is important to remember that other processes (erosion, weathering, transportation, deposition, mass movement) also contribute to the formation of these features.
- 4 River valleys and river channels are not the same thing.
- 5 Remember that flooding can bring benefits as well as costs.
Top facts to use in your essay answers
- 1 Water covers approximately 71% of the Earth's surface
- 2 96.5% of the planet's water is found in oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air.
- 3 Only 2.5% of the Earth's water is freshwater, and 98.8% of that water is in ice and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere.
- 4 The Amazon river is by far the largest in the world in terms of discharge (which is greater than the next seven largest rivers combined), and it has the world’s largest drainage basin. The Nile is generally recognised as the world’s longest river (approximately 6550 km).
- 5 River flooding has been the cause of some of the world’s worst environmental disasters. For example, the 1931 Yangtze floods in China may have killed up to 4 million people.
Investigation of the distribution and abundance off reshwater invertebrates in the Tillingbourne River at Abinger Hammeron Thursday, 17th of October 2002
Dissolved Oxygen (O() levels are going to be greater at the middle of the river because the warm water in the middle of the river will not hold onto as much oxygen as the supposedly cold water at the edge of the river. 4. More invertebrates will live at the edge of the river because they have the adaptations to live there. * * There is less competition to live at the middle of the river because there are fewer invertebrates there and the invertebrates that live there adapt by having suckers, which are used to suck onto stones.
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An Evaluation of the Economic, Social and Environmental impacts of building the Aswan d*m on the people and environment of the River Nile
This basin irrigation supported one good crop a year." (A modern Lake Moeris: Wadi Rayan by Gregory Baecher.)" The River's water and the fertile soil along its banks created the perfect setting for the evolution of the civilisations that existed in the ancient world. Ancient peoples lived along the Nile's banks and cultivated the art of agriculture As the Nile was so significant to the way the ancient people went about everyday life, many statues and monuments were built to mark its importance.
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The annual precipitation varies very little as a result, ranging from between 540 and 640 mm. Annual potential evaporation is approximately 520 to 540mm. However the upland areas receive much higher amounts of precipitation. High rainfalls over the tributaries of the Ouse make it very prone to flooding, as the tributaries are unable to cope with amount of water. Much of the catchment of the River Ouse and its tributaries is used for farming.
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Climatic factors are the most obvious conditions that can affect the flood hydrograph. If the precipitation is very intense and there is a lot of it then the hydrograph is likely to have a high peak discharge where as if the precipitation is low-intensity and there is a small amount then the graph will have a gentle ascending limb. The ascending limb is the first part of the line on a hydrograph that rises to the peak discharge. If the gradient is steep (like the example on the right) then this can indicate that the amount of rainfall becoming overland flow is very high, the result of this is that all the water
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With reference to examples where appropriate, what is a sediment budget and how does this have both positive and adverse effects within drainage basins?
What the sediment budget shows is the amount of sediment which leaves a catchment area, and how much of it stays and is stored there. Most of the sediment is stored at the floodplain, though there will always be some others along the river's course. By looking at an example we can see this more clearly. The sediment budget for the River Start, South Devon, shows, firstly, all of the 107 tonnes/km squared/year of sediment is transported to its first catchment area, and 15% of the sediment is deposited here at Hedgerow.
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We also identified if it was possible (in some cases we couldn't see) where the fastest flow looked to be. Other things we drew were pipes and that were intercepting slightly with the river's flow. I think that many people would be interested in and benefit from this study. People such as younger students who want to know about rivers and how they work, or even just to find out how to study the river. It would also be of interest to anyone who has a particular interest in geology or it could even be to the interest of the Buckinghamshire County Council who could use the information to try and prevent things such as pipes and rubbish from intercepting and polluting the river.
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For One Named Drainage Basin, discuss the Strategies and the Benefits of River Restoration or Ecological Management.
reduced flooding on the floodplain as water stayed in the drainage basin for eleven days and channelisation reduced it to one day. It was designed to control the river and prevent flooding. The channelisation had many effects on the ecosystem, which meant that its biodiversity decreased, for example, loss of wetland habitats causing 92% fewer birds in winter.
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It works exactly the same way for a river; the steeper the bed the faster the water will move over it. Also the smoother the river bed is the less friction there will be and therefore the water will more over this bed faster (the river bed becomes smoother due to erosion.) Another reason for the change in velocity is the landuse. Toward the source of the river Roe there is the Glenshane forest and the land is boggy or peaty, while the mouth and lower section has been drained by the surrounding towns or urban areas.
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Assess the different ways in which we can use river environments and identify the different conflicts that occur
The industry such as a hydroelectric power station has developed in the Pennies, and also quarries, as there is little settlement around to cause conflict with. Forestry also takes place on the valley sides where land is cheap. The River Tees is also used as a water supply as reservoirs where created in the Pennies, which also are used for recreational activities. The population density is low due to the limited employment opportunities and consists of isolated villages found along side of roads and on the lower valley sides.
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Results Velocity Site one Site two Site three 1st cork 75.92 secs 18.98 secs 33.90 secs 2nd Cork 82.26 secs 21.46 secs 31.90 secs 3rd cork 50. 30 secs 22.93 secs 32.83 secs Average Cork 69.49 secs 21.12 secs 32.54 secs Speed of river 0.14 m/s 0.47 m/s 0.31 m/s Conclusion From the results, you can see that a site one the river was flowing at the slowest speed, at site two it was fastest and site three was in between the both.
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Compare the observations and recordings made at the two sites with predictions made from the characteristics of a ‘theoretical’ river.
Map showing area covered by the River Bovey and the location of the two sites studied: Scale: 10km River Bovey: National Park boundary: Site 1: Site 2: Hypotheses The purpose of this fieldwork is to compare the observations and recordings made at the two sites with predictions made from the characteristics of a 'theoretical' river. The three factors that I have chosen to make hypotheses on are i) the average velocity of the river ii) the bedload size and iii)
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Two major erosional processes occur at the base of a glacier. At the base of a glacier, large amounts of rock and sediments are incorporated into the glacier's ice. The material in the ice then acts as an abrasive agent when combined with glacier movement. This process is known as abrasion. Abrasion creates a variety of features; the most conspicuous of these is striations. Striations appear as scratches of various sizes on rock surfaces. Striations can be found in virtually any glacial environment, a good example of these though is Lac Blanchet in Canada.
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Bed material also moves in traction which is when large boulders trundle along using smaller stones as ball bearings. The bed load (material of all sizes) travels slower than water. The bed material can also be transported as suspended load. Particles move with the main body of water. In this project it is not possible (given the amount of time) to study each of these processes and its results. I will be investigating the bed-material load(size and shape). This includes traction and saltation. BED MATERIAL LOAD Unlike the transport of the dissolved and wash load, the rate of bed-material transport is almost entirely a function of the transporting capacity of the flow.
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Also the river had quality's which meant it would not be too hard to study. As we only had basic equipment, tape measure and metre rulers, if the river had been too deep or too wide we would have had a lot of trouble taking even these simple measurements. The river was also "manageable" by this I mean that the river was not too fast, if the river was too fast it could have been dangerous too stand in the river.
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3) Bedload size and shape will decrease downstream. Background and Theory of river processes 1. Hydrological Cycle 2. River Processes - Erosion Deposition Transportation 3. Other Factors affecting a river Erosional Processes Erosion is a process whereby material carried by the river wears away the bed and banks. It causes the river dimensions to become wider and deeper, or in the case of river material, smaller and rounder Erosion occurs through four processes: * Abrasion- A sand paper effect, where materials rub along the bed and banks of the river causing them to erode. This process is more effective during times of flood and is the major method by which the river erodes both vertically and horizontally.
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China’s headlong rush into the modern world may involve a heavy price in terms of environmental damage: Discuss.
of great political and economic significance ...It proves to the whole world the Chinese people's capability of building the world's first rate hydroelectric project" (Treager, 1980). Thus the construction of the d*m has become as much a celebration of Chinese nationalism and its political leadership, as it is a massive power and engineering feat. This as such makes dealing with many of the problems of the project all the more difficult. To be able to understand the environmental factors that building the d*m will cause you must firstly look at some of the facts and figures surrounding the construction and running of the enormous project.
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Bevendean, like other sites around Brighton, has a long history of flooding and serious soil erosion. In 1982 the farmer at Bevendean, on being asked if he had an erosion problem, replied no. He later pointed to a field where he had lost a cow in a gully. Bevendean houses were also flooded in 1985 and 1987. Between 1976 and 1993 there were 60 floodings in the Brighton area. A substantial number will have been added this autumn. In October 1987 at Rottingdean, 3km from Bevendean, around �400,000 of damage was done to about 30 houses.
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In some places the ground level raises over 500m in under a kilometre of land. There are many cliffs because of this; these make brilliant viewpoints. People and tourists try to make the best use of the Cairngorms they can. It is used so much to its full potential that people are actually damaging it. In Aviemore, there are many attractions. There is a cinema and theatre, these both play new and old films and plays. There is an up to date ice rink and artificial ski slope. There are lots of natural trails that people can take leisurely walks along.
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River management schemes concentrate widely on reducing flood losses, rather than preventing flooding altogether. Embankments, Levees, and floodwalls. A levee is a barrier that holds water away from the surrounding buildings and land. It can protect your home from flooding as well as from the force of water from rivers. A properly built levee takes a lot of space. Its sheer mass keeps it from moving. Long, gentle side slopes increase stability and provide for easier maintenance. Levees must be built to withstand the forces of standing water and flowing water. The main function of a levee is to restrict flooding to defined limits and to allow easier control of flooding in certain areas.
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2. To see if width, depth, velocity, bedload size, biological content and chemical content change downstream. HYPOTHESIS 1. Width should increase with increasing distance downstream. 2. Velocity should increase with increasing distance downstream. 3. Depth should increase with increasing distance downstream. THEORY An ideal river THE UPPER COURSE- In the upper course, the river is above its base level.
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The river begins with many meanders but further downstream it straightens out and then meanders again. On the edge of the river side the land had been eroded (undercutting) and the land was soft clay. The weather on the day of study was sunny with a slight breeze. There was some vision of human activity in the drainage basin; there were quad bike skid marks and farmers.
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There are two types of glaciers, cold polar and temperate. Cold glaciers are in very cold areas where there is minimal melting, only 1-2 cm a day due to little friction because it is frozen to the bed and is on gentle slopes. The ice crystals face the direction of the movement so they can slip past each other therefore the surface of the glacier moves faster causing deep crevasses. Temperate glaciers are in areas with milder summers and steeper slopes.
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York was again hit by a major flood in 1982 when flood levels reached 16feet high. York is often under threat to flooding because of its situation. The river Ouse is the principal drainage basin in Yorkshire. The Ouse is formed by the confluence of the Ouse, Gill, Beck and the river Ure, a few kilometres downstream of the confluence of the rivers Swale and Ure. The Ouse the flows southwards and is joined by the Nidd just to the north of York.
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The top two layers are essentially free draining while the lower layers are relatively impermeable. This gives rise to a series of springs which emerge at the junctions between different layers. These springs are the source of a number of streams which drain the edges of the Epping Forest ridge. One of the largest is Loughton Brook which rises near High Beach and flows through the urban area of Loughton in to the River Roding. In the past, the area was used as a Royal Hunting Forest, but was also used by local people for grazing and as a source of fire wood.
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Middle Course of Burbage Brook The middle course of Burbage Brook is a 'V within a V' shape. The valley is slightly wider here than the upper course of Burbage Brook also the valley sides are much gentler. It also meanders side to side caused by interlocking spurs (look at the diagram below about a meander). The valley sides widen due to lateral erosion. Lateral erosion takes place here because the velocity of the river is much slower than what it is at the upper course of Burbage Brook (refer to the middle course bar chart of Burbage Bridge to find out the velocity).
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