How and why does the valley width change downstream? 2. How and why does the channel width change downstream? 3. How and why channel cross-section change downstream? 4. How and why does the average velocity change downstream? 5. How and why does the channel gradient change downstream? 6. How and why does the bed-load change downstream? 7.
How and why does the human land use of the valley change as the river moves downstream and does this Impact on the river? Introduction Carding mill valley is in Shorebird, England.
It is 22. Km northwest of Trochaic; it is part of long mind. The valley in total stretches 2 miles and spans 5 sq miles in total. The long mind is a stretch of hills literally translated from welsh as Long Mountain, they stretch for 7 miles. The valley cuts into the long mind so therefore it is part of the hills. The valley has a few types of vegetation on top of grass such as heather, bracken, bilberry and gorse.
There is also an abundance of animals especially sheep and birds, there Is also a disused reservoir which will have a lot of aquatic life.
The valley was formed 600 years ago by volcanic activity. The rocks In the hills and valley are 560 million years old. At the top of the valley there is a waterfall that is called tight spout waterfall that is fuelled by mm of rainfall they get each year. The valley is now maintained and looked after by the national trust, which initially took over in 1965 and then completely took over in 1979.
In the valley there is now a shop, cafe© and a gabion that is helping prevent the erosion. In the valley you can simply go for a walk or partake in some more exciting activities such as hang gliders, there is also a tearoom with great views and surroundings. [pick] Climate graph We can see from my climate graph that there are general trends such as mild temperatures In autumn Ana spring out really quilt cola temperatures In ten winter and very warm temperatures in the summer, the temperature go from a low of 2 degrees in December to a high of 16 in July.
Yet again there are trends in the amount of rainfall, firstly there is rain all year round but the heaviest is found in November with 99 mm of rain and the low is found in July with 29 mm of rain. Carding mill alley is found in a temperate climate, which is the same as the whole of the United Kingdom, this means there are no extremes of rainfall or temperatures. Sketch Map Methodology Measurements we took 1) Valley width. 2) Channel width. 3) Channel depth. 4) Gradient. 5) Velocity. ) Bed load (longest axis and shape) 1) Valley width We use this tape measure to measure how wide the valley was. We measured from where there was an incline in height on one side to the same on the other. 1) Channel width We use the tape measure again to measure how wide the channel of water was. We simply measured from one side of the channel to the other. 3) Channel depth When we measured the channel depth we put a tape measure across the channel and then we put a meter ruler into the water and measured how deep the water is in CM. We did this every 25 CM. ) Gradient 10 measure ten gradient we put ranging poles Into ten ground or rollover at distances of 10 meters apart we used 3 poles in total. We then lined up the sights of the clinometers up with the two second red stripes on two of the poles as shown above. 5) Velocity To measure the velocity of the river we place a cork in the river and timed how long it kook for it to travel 10 meters. To measure the bed load we selected 6 rocks from the bed of the river from all 6 sites and measured the longest part of the rock, this will be its length.
Then we looked at the shape of the rock and compared it to our guideline to determine whether it was very angular, angular, sub-angular, sub-rounded, rounded or well rounded. Results 1. Valley Width 2. Channel width 3. Channel Depth, Cross-section Profiles 4. Gradient 5. Velocity 6. Bed Load Longest Axis 7. Bed load shape Types of erosion Abrasion/corrosion Rocks that are carried in the river grind and erode the riverside and bed. Some of the rock at the sides and bed of the channel are washed away. This type of erosion widens the channel through lateral erosion and deepens the channel by vertical erosion.
Hydraulic action Water traveling at a high speed may enter the line of weakness of rock when it hit against these rocks at the side of the channel. The force may cause the rock to break Ana ten Drone pieces AT rock are swept away Attrition When material in the water collides with one another, they break and become smaller particles. These particles become smoother and rounded. Solution/ Corrosion The river water may also dissolve the minerals in the rock and carry them down the river. Limestone may be dissolved quickly in the river water, especially when there is high concentration.
Analysis of data Valley width We can see in my graph that as we move down stream the valley widens at a slow rate to begin with but it get more rapid the further we go down the valley. I can show this by using my results as I said the valley starts off at a slow rate of widening of 4. Mm to 6. Mm and again up to mm so this clearly is a gradual increase. Whereas it jumps to measurements of 1 5. Mm to 29. M and then to mm, this shows the rapid increase. This is an increase of 34. 73% from the top of the valley to the bottom; this is taken from a minimum measurement of 4. Mm and a maximum measurement of mm. Types of erosion involved in this are abrasion/corrosion, which is Rocks that are carried in the river grind and erode the riverside and bed. Some of the rock at the sides and bed of the channel are washed away. This type of erosion widens the channel through lateral erosion and deepens the channel by vertical erosion. Also Hydraulic action is an affect where water traveling at a high speed may enter the line f weakness of rock when it hit against these rocks at the side of the channel.
The force may cause the rock to break and the broken pieces of rock are swept away. These causes get stronger as we move down the river as they pick up speed and extra sediment and rocks to cause the erosion. The most important type is abrasion as it is the most destructive erosion and as for the time of year that it is most prolific is winter as the volume of water coming down the river is greater so the amount of rock it can carry increases. The valley widens as the channel widens hence the types of erosion mentioned.
Channel width We can pick out from the individual graph and the combined graph that the channel width increases as we move down stream. However there is an anomaly in these results, which could have many explanations such as harder rock or the river, slows at this point. The widths on the whole increases by nearly triple its original width. As for erosion it will have the same types as valley width as the channel width dictates the valley width. So there will be hydraulic action, corrosion and abrasion at work.
The patterns Tanat are clear on ten graph all T t a general pattern AT ten Turner down alley you get the wider the valley and the channel gets. Channel depth As we look at my channel cross-sections it tells us clearly that as we move down stream the channel widens and with it gets deeper, this is this because of the types of erosion happening which are; abrasion/corrosion, attrition, hydraulic action and corrosion. It goes from a minimum depth of CACM to a maximum depth of CACM so that’s an increase of 2 fifths.
I have found one anomaly in my results of site one which is the deepest but that could be because of the amount of water hitting it from the plunge pool little further up. Gradient The gradient is steeper at the top near the source as it is coming down out of the valley but as you go further down stream its gets flatter as we come down out of the hills and down to the bottom of Body hill. It changes from a high of 12 too low of 2 this is a decrease of 2/3rd. An anomaly may be that there is no decrease between site 5 and 6 so there is only the force of upstream pushing the water through.
There are a few types of erosion causing the change in gradient as corrosion and abrasion forcing the land to recede downwards, this changes the shape of the valley I ways such as the valley itself gets deeper and in some places causing mini waterfalls as there may be harder rock that is not eroded so easily. Deposition occurs in quantities and this affects the gradient, as it will flatten it out, as there is new bed load all the time. [pick] In the lower valley there is more lateral erosion than vertical erosion as there is not so much force pushing down where the waterfall is pushing down rather than the river pushing forward.
Velocity As we move from site 1 to site 6 we see that the velocity has ups and downs there is no definite pattern between the results as they start at 1. 6 and then drop suddenly to 0. 96 but then they steadily go up so this result may be an anomaly from rock on the bottom that the cork got stuck on or maybe a small plunge pool that it got stuck in but to look at the results do not look like they have a definite pattern. But from the lowest result to the highest result there is an increase of almost double the speed.
The velocity is going to change as near the plunge pool where the velocity is going to be high the amount of angular rocks will slow it and with the small channel width and the large wetted area will cause more friction and slow the cork and velocity own. Load longest axles Ana load snaps As for the bed load shape at the top of the stream the rocks angular and sub angular, as they haven’t had time to get eroded and smoothed over yet, as for the bed load length it starts off at the top as a maximum of 12 CM and then down to the bottom where the maximum length is 7. 6 so that is an increase of about h, so at the bottom of the valley the rocks start to become more rounded and sub rounded. So in summary the further you go down they valley the smaller and more rounded they are but up the top they are longer and more angular. In my results there are no anomaly to be found for the bed load shape but as for the bed load length there are some from site 3 and site 5 where they are much smaller than expected this could be because they got trapped in that position and eroded in that place instead of moving down stream and getting eroded on the way.
The bed load shape will defiantly change constantly as the new angular rock is supplied at the top from it falling from the weathered valley sides, but further down stream the sediment has been eroded in transportation by attrition, corrosion and abrasion, which will make them smaller and more rounded. Human analysis of carding mill valley Man has influenced this area and the river in many ways, which will affect the state and the activity of the river.
Firstly the excellent walking areas around draw hikers to the area this causes paths and walkways around the area. This will affect the valley as they put down tablets of stone which are impermeable to water cannot get into the soil and make it to the river via through flow this will increase surface run-off which will keep water on top of the ground and increase the chance of flooding, however they space to slabs a little apart and do not cement them down so there fore he water can still enter the earth.
On the upland there is beautiful heather which could become ruined by people taking cuttings or dropping litter which affects the wildlife as the heather may be their home and they may try to eat the litter or dropped scraps, this may in turn make them dependent on humans which makes them less wild and move away from their inherited lives but this can be resolved simply by putting fines on litter or putting more bins around the site. Hand gliders love it there to as it is high and beautiful but Para gliders will cause noise and air pollution.
Tourist activity has affected it by laying concrete and pavements which are impermeable increasing surface run-off and increasing yet again the possibility of flooding and in turn lowering the amount of water making it to the river and being taken away but they have put a man made drainage system in to combat this problem, they have also put hard rock barriers up to stop its natural course and dictating where it goes however the have put gabion up to stop the river destroying the landscape by eroding the valley too far and causing landslides.
The tourist attraction and the education centre put together will increase the amount of visitors sleeve wanly all affects ten ruler, Decease tense wall De many people wall De walking up and down the valley all the time which will cause erosion on the grass and soft land. The hiking routes are well marked but the walkers may well go off track and cause damage on unmarked land where it needs to be preserved.
The main thing that makes the place so popular to humans apart from the spectacular views, easily accessible and lots of wildlife is that its free so therefore at least 250,000 people visit the site each year so that will cause a lot of pollution and erosion, this ill also cause more conversationalist which means more tarmac and impermeable surface and more land covered which decreases interception which helps against floods. As the valley has at least mm of rain per year which is a good amount.
The valley was made by volcanic activity 600 million years ago so this draws more people especially as it has some of the oldest rock formations in existence. The whole valley is covered in heather, bilberry, bracken and gorse which all helps with interception, transpiration and stem flow but as this gets cut back to build tourist attractions it will increase the amount of water going into the river causing increased chance off extreme flooding. pick] This diagram shows the system that happens to a place that has had nothing done to it in terms of tourist activity, Housing and human activity at all but when humans do step in the amount of over land flow, surface storage and soil infiltration decreases dramatically so therefore the amount of drainage basin output will be way too low so as a result there will be a massive increased threat of flooding.
So basically there has been no building to increase interception and there is o tarmac to increase the surface runoff. Conclusion 1) The valley width changed down stream due to the given types of erosion such as hydraulic action, corrosion, abrasion and attrition. It does this because erosion cuts into the sides and bed of the stream and therefore it gets wider and deeper. The channel does this, as that is what causes the erosion. ) The channel width changed in ways of wider and deeper from erosion that grinds into the side of the channel so the further down the stream the wider it gets and the same happens to the depth but instead of lateral erosion it goes vertically. ) The cross-section changes as you go down the stream in ways of lateral and vertical erosion because of all types of erosion. The depth is always deeper towards the top as the water is coming down out of the hills so it is coming vertically but the further down it begins to flatten out so therefore it starts to get wider. ) The velocity is greater at the top because the gradient up the top is greater than down the bottom so its obvious that as the gradient flattens out the velocity gets slower. 5) The gradient changes due to the direction of erosion so at the source it is vertical erosion due to the plunge pool but as you go down the erosion turns into lateral erosion so odometer ten gradient neatens out. 6) The bed load starts at the top with weathered rock falling from the valley.
It is angular when it falls in and it’s rather large also. As the rock travels down the stream it gets eroded from corrosion, abrasion and attrition. 7) The human impact affects the river in ways such as dictating the course of the river and also it will not get any through flow water as the ground is covered with concrete and tarmac. Evaluation Large wetted area Angular rocks Small plunge pools