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AS and A Level: Hydrology & Fluvial Geomorphology
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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.
There are however many different types of condensation just like there is for precipitation. Radiation cooling occurs when the ground loses heat very quickly through terrestrial radiation and the air that is in contact with it is cooled by conduction. If the air that is affected by this process is humid then fog or dew will form. This usually happens in the evenings when there is typically a clear and calm sky. Advection cooling is likened to radiation cooling because they involve horizontal rather than vertical movements of air, which means that the amount of condensation created as a result is much, lower.
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Also we plan to look at all the different processes operating within the river from its source to mouth; this data will be presented in graphical form. Hypotheses 1. Width, depth and cross-sectional area will increase from source to mouth. 2. The velocity and discharge of a river will increase from source to mouth. 3. Bed load becomes smaller and more rounded from source to mouth. Location Our study is of the Glendun River. The map below shows part of Northern Ireland and where the river is positioned.
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For a secondary data source I used an ordnance survey map of the Limavady catchment area (1:50,000) to measure the distance between sites on the river as well as locate any nearby features that may be useful. I also used Power's roundness index to identify the shape of bedload particles. The sampling method I used was a combination of pragmatic systematic sampling to locate suitable sites of equal distance along the river and random sampling to choose various bedload particles.
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Flow I measured the flow of the river by firstly getting one member of my team to carefully stand in the river at the left side near the bank. That person then dropped one of the plastic balls into the water. When the ball had travelled the 10meter length I had measured for it to travel, I stopped the stopwatch and record time on my data sheet. I repeated this procedure three times for the left, middle and right side of the river of get an average to make it a fair result.
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The characteristics of air temperature at a mountain station Grachen, in Wallis and the river flow from a glacierised basin Kanton Wallis in the Swiss Alps
This is done by using chart wizard. We them used the XY (scatter) The data that we used to plot the graphs was the temperature against the discharge of the river and the years which were involved in the data. This graph was different to the graph that we had done before. We had 3 different types of data to put into 1 graph. This was carried out like the any normal graph, by selecting the graph we want and selecting add data, this then gives the option of adding more data by selecting the cells required and then clicking ok puts the three Once we had
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This is where the river is straightened out bout in terms of its course and in terms of its bed and sides. This is done to reduce the friction that sides have on the water and this in turn increases the water velocity. A faster flowing river also prevents sediment dropping on the riverbed and reduces the need for dredging. This also has a knock-on effect in that it protects the banks from erosion, and protects upstream from flooding.
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* Only takes one person The problems of this test is that: * You have to make sure the can is in the ground properly so the water doesn't escape and therefore wasting water. Pupil with the equipment 1. Water 2. Tin can 3. Stopwatch Soil Auger Test This test will tell us how deep the soil is in a section of the ground. The list of equipment needed is: * Soil Auger * Soil to Auger * Meter Stick To do this test start to screw the auger into the ground in a clockwise direction.
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As a group we have decided to look at the changes in a river in the Gortin Glens. Our study took place on the 23rd of May 2007. We decided to study the changes in a river as it travels downstream
From the map you can see that the source of the river begins at approximately 490m. There are several smaller tributaries that make their way into the channel of the Pollen Burn and they have been shown on the map. Thematic Context Drainage Basin A drainage basin on river basin is an area of land drained by a main river channel and its tributaries. Boundaries between drainage basins are called a watershed, which is a ridge of higher land separating two or more river basins.
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The upper course is the start of the river. This is known as the source. The upper course is typically steep and straight with lots of fast flowing water. The source of the River Tees starts is journey in Cumbria at 600 metres above sea level. A succession of falls or rapids, where the river traverses a hard series of black basaltic rocks, is called "Cauldron Snout". From a point immediately below this to its mouth, the Tees forms the boundary between the traditional counties of Durham and Yorkshire almost without a break, although since 1974 much of it lies wholly in Durham.
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The water that had risen was more than a foot over the danger level. The water that flooded the land was infested with many water born diseases, this water became mixed with the drinking water for many people. All of these problems are aimed to be stopped by the building of the 3 gorges dam. The main problem that the 3 gorges dam aims to solve is the major flood problem from the rivers. These floods are normally caused by the heavy rainfall in every monsoon season and making a massive increase in the river flow in June, July and August. This increase is added to from the snow melt from the Himalaya Mountains.
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Urbanisation on the flood plain was also a major factor as grass and tress have been covered over and concrete and tarmac. Replacing a permeable surface with an impermeable one has many effects on the river. Movement (transfer) of water into the soil from the surface (infiltration) is reduced dramatically along with throughflow, whilst surface run off is increased. This is because when trees were on the flood plain they had four jobs which helped keep the possibility of flooding to it's minimum a)
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There are lots of obstacles, stones and boulders for the water to flow over. As the river moves all the way through the upper course it cuts downwards. The steepness here is steep and the river channel is narrow. Vertical erosion in this highland part of the river creates steep sided V-shaped valleys and interlocking spurs. These are caused as the river erodes the landscape in the upper course, it winds and bends avoiding areas of hard rock. Therefore creating them they look a bit like the interlocking parts of a zip. The graphic shows how waterfalls and rapids are formed.
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With an increasing economic strength, the Chinese Communist government can afford huge public works such as the Three Gorges dam which they believe will benefit the economy further in the future. Presently (2007) the structure of the dam is said to be completed although it will not be fully operational until 2008 when it will be able to generate electricity at full capacity. The River Yangtze The River Yangtze is the world's third largest river which flows for a total of 6,211km from the Tibet in the West through China and ends in the East where it branches of as a delta into The Pacific Ocean.
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According to Bradshaw's model, the hypothesis is that "Stream characteristics (i.e. cross-sectional area, discharge, velocity, efficiency, and gradient) all change along the course of the river and they are related to each other". Source Mouth The diagram above displays Bradshaw's model river. From this, we can see that the hypothesis briefly states that the characteristics of a river, namely cross sectional area, discharge, velocity, efficiency and gradient, all have a tendency to vary along with the movement of the river. Also, the hypothesis states that they are all interrelated: if one characteristic differs, then so will the others.
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Gilbert therefore believed that a graded channel is the inevitable product of a river using up excess energy and once a river reaches a graded condition it is in a state of equilibrium and unable to deepen their valleys or change the form and gradient of their long profiles directly. According to Briggs & Smithson a graded profile is necessary to erosion and transportation as 'In the upper reaches of the stream, the discharge is low and the sediment coarse.
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As the water flow progresses downstream, the river channel should become wider and deeper due to lateral and vertical erosion
This is because more tributes add to the water flow as you get further downstream therefore the velocity of the river increases. The speed of the water rushing past causes lateral erosion in the river banks and vertical erosion in the river bed - making the river both wider and deeper.
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Due to this the Severn, in particularly the Shrewsbury area is historically known for its proneness to flooding. It is expected on average for there to be a major flood in the area once every 10years, however there had been no such flood for over 30years. The urban area of Shrewsbury is built on higher ground to the flood plain of the river so there have been no floods of any severity. Unfortunately between October and December 2000, 3 major floods were experienced in the area. On the short term this had a huge impact to the busy market town.
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To assess whether the modified channel of the river ash is effective in reducing the risk of flooding to local homes.
This causes a large amount of surface run-off when water simply lies on the surface of the ground. This surface run-off can initiate flooding. In Britain flooding often occurs in summer. After large periods of dry hot weather the ground becomes hard and dry and hard to infiltrate. A heavy rainstorm can often follow this where the surface run-offs caused by poor infiltration results in a rapid rise in water level, or a flash flood. Heavy snowfall means that large amounts of water are held in storage. If there is a slight rise in temperature the water melts and is released.
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Stop 2 G.R.-512 805 This stop is similar to Stop 1. There are many different types of rocks and the river is still fast moving. Boulder clay is also present on top of which vegetation has formed . This stop also has its own micro climate compared to the mountain top because it is in a valley. This enables Mountain Ash to grow which is the first tree growing down the mountain because it is sheltered in the V-shaped valley. Some of the features found at this stop include interlocking spurs and V-shaped valley.
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My aim is to investigate, using the Curley Burn River, a 4th order tributary of the River Roe drainage basin, the relationship between the changes in the river and the distance down stream. I will formulate 3 hypotheses around the river model
waders * A spare set of clothing had to be brought * There had to be risk assessments of the sites we were visiting * Buoyancy aid and hard hat had to be worn at all times * Open cuts had to be cover before going to the river to prevent Weil's disease * There had to be the safe use of equipment * An emergency plan had to be made and someone else not going to the field must have known where we were * A mobile phone had to be brought out on the field in the case of an emergency * First aid kit Sampling: We used a technique called pragmatic systematic sampling.
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This introduction is going to be about rivers and how they shape the landscape. Rivers are an important thing to study because the study of rivers
Some people would like to know the processes responsible for the development of selected landforms and the role of rock type and weathering', and the 'causes and effects of a related hazard (flooding or landslides) and human responses to it'. People also need to understand the uses of rivers. They can be as a source of water supply, the production of hydro-electric power and a place that hosts leisure activities that people like doing such as fishing, rowing etc. Rivers are also used as major transport systems and market routes e.g.
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I will be analysing six different sites in the River Wye, at the western part of the Peak District. The six sites that I am visiting and investigating are: south of Buxton, eastern part of Buxton, Millers Dale, Litton Mill, Ashford on water, Bakewell.
So why do we Study Rivers? We study rivers because just like us human beings have homes, the flora and fauna also live and have their own territory. This means little water creatures have their homes under rocks or on top of the rocks in order for them to survive. Furthermore foods webs help us also identify what kind of producers, consumers live and how they survive. Nevertheless, some rivers like the River Thames also run through cities. We also obtain knowledge about the speed of the river, whether the river is oxygenated or the bedload in the water is affecting the landforms causing it to erode.
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To what extent the flood alleviation scheme has had on the environment and people of Swanage and to find out weather the scheme has been successful.
The headlands of Swanage are quite obvious and easy to notice. Both the chalk and Purbeck bed are hard rock which is found to the north and south of Swanage. The soft rock has been severely eroded in comparison to the other rock, especially the chalk found at Studland Bay. This is where the famous 'Old Harry' stands. This site receives a lot of tourism and still has been eroded less than the Swanage area. Question 2 In any place there is obvious causes of flooding, the most common cause of flooding is heavy rainfall over a long periods of time, often lasting many days, thunderstorms being the most severe of these.
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My hypotheses are:The character of the course of the River Bollin will change along its course to the mouth. The bed load will decrease and angularity of the materials found in the river will be reduced. The velocity
This was also a good way of reinforcing our knowledge of the hydrological cycle, as we could physically see the precipitation further up the hill, and how it trickled down to create streams. We planned to go to the highest and furthest site first, this was a perfect example of the beginnings of a river, or it's Source. This site was found in the "Macclesfield forest", and so we shall refer to the site as Site 1, Macclesfield forest. This site showed the characteristics of a V shaped valley, and formed truncated or "interlocking" spurs.
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