• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13

Does the river Alyn follow Bradshaw's model?

Extracts from this document...

Introduction

Does the river Alyn follow Bradshaw's model? Introduction What is Bradshaw's model? The hydraulic geometry of rivers varies throughout their course. Bradshaw's model is a general model for how different river variables change downstream. Below is a diagram showing Bradshaw's model. Aim of my investigation The aim of my investigation is to see how the river variables change on the river Alyn and how this compares to Bradshaw's model in terms of 2 key questions: * How the velocity of the river Alyn changes along the profile? * How the Discharge of the river Alyn changes along the profile? Hypothesis Following Bradshaw's model I would expect both the river velocity and discharge to increase the further you travel downstream. Theory Velocity is the speed that the water is moving. It is measured in metres per second. The theory behind velocity increasing downstream is that it depends on 3 factors: Channel Gradient, Channel Roughness and Channel Shape. * Channel Gradient - Due to gravity the greater the channel slope the greater the velocity if other factors remain constant. * Channel Roughness - The rougher the channel is (how many rocks and boulders are found in the river channel) the more obstacles there are opposing the waters flow leading to increased friction and decreased velocity. The channel is less rough the further you go downstream and so the river flows faster. * Channel Shape - This is described by hydraulic radius. This is the ratio between the cross sectional area of a river and its wetted perimeter. For example if two rivers have an equal cross sectional area the river with the greater wetted perimeter will have more friction and so the velocity will be less. River A River B Both river A and B have a cross sectional area of 60 m�. However river A has a wetted perimeter of 62 metres where as river B has only has 22 metres of wetted perimeter. ...read more.

Middle

25 1.39 10 0.33 15 5 25 0.74 15 0.72 13 2 4 =294 Cross-sectional Area Rank Velocity Rank D D 2.42 4 0.38 12 8 64 1.34 11 1.1 1 10 100 1 14 0.9 4 10 100 1.94 7 0.57 10.5 3.5 12.25 2.58 2 0.58 9 7 49 2.44 3 0.27 14 11 121 3.19 1 0.65 7 6 36 2.29 5 0.57 10.5 5.5 30.25 1.16 12 0.51 11 1 1 0.50 16 0.34 13 3 9 1.69 9 0.6 8 1 1 1.08 13 0.91 3 10 100 2 6 0.83 6 0 0 1.85 8 0.88 5 3 9 1.39 10 0.24 15 5 25 0.74 15 0.97 2 13 169 = 826.5 Hydraulic Radius Rank Discharge Rank D D 0.214 7 0.92 10 3 9 0.11 12 1.49 5 7 49 0.16 10 0.9 11 1 1 0.283 3 1.1 7 4 16 0.231 5 1.5 4 1 1 0.238 4 0.66 14 10 100 0.355 1 2.07 1 0 0 0.151 11 1.3 6 5 25 0.019 14 0.83 12 2 4 0.07 15.5 0.17 16 0.5 0.25 0.104 13 1.02 8 5 25 0.169 9 0.99 9 0 0 0.225 6 1.66 2 4 16 0.284 2 1.63 3 1 1 0.17 8 0.33 15 7 49 0.07 16.5 0.72 13 3.5 12.25 = 308.5 Hydraulic Radius Rank Velocity Rank D D 0.214 7 0.38 12 5 25 0.11 12 1.1 1 11 121 0.16 10 0.9 4 6 36 0.283 3 0.57 10.5 7.5 56.25 0.231 5 0.58 9 4 16 0.238 4 0.27 14 10 100 0.355 1 0.65 7 6 36 0.151 11 0.57 10.5 0.5 0.25 0.019 14 0.51 11 3 9 0.07 15.5 0.34 13 2.5 6.25 0.104 13 0.6 8 5 25 0.169 9 0.91 3 6 36 0.225 6 0.83 6 0 0 0.284 2 0.88 5 3 9 0.17 8 0.24 15 7 49 0.07 16.5 0.97 2 14.5 210.25 =735 Velocity Rank Discharge Rank D D ...read more.

Conclusion

When calculating the cross-sectional area the measurements we took were very inaccurate. Again a number of factors contributed to this: firstly some measurements were only taken to the nearest 10 cm whilst some were taken to the nearest centimetre or millimetre. Although the odd centimetre may not seem that important it can have a large affect when it is multiplied to find the cross-sectional area and then multiplied again to find the discharge. There were also potential errors with the equipment we used. It is possible that sometimes there might have been some slack in the tape measure giving us an overestimate of the actual widths. Also, the measurements for width may not have been in a straight line perpendicular to the riverbank. If a slightly diagonal route was taken when measuring to the opposite bank this would increase the distance measured. When measuring depth we only took 3 measurements to try and gain an average for the whole of the channel. Although this is better than taking just one measurement it is still gives quite an inaccurate reflection of the actual depth. Other problems with my investigation include the fact that I only tested the area at one time of year. At different times during the year the discharge of the river changes, but we can't tell if the whole rivers discharge would rise or fall by the same proportion. For example in the summer the part of the river nearest the source might lose 10% of its water but further down the river it might lose that 10% and a further 10% due to other tributaries drying up, This means the discharge would change by different amounts at different parts of the river. Although the investigation would have been more accurate if carried out over a larger section of river I did not have suitable resources or equipment for measuring on a large scale. It would have taken a considerable length of time to record data for a large enough sample. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Hydrology & Fluvial Geomorphology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Hydrology & Fluvial Geomorphology essays

  1. Study the downstream changes of Loughton Brook.

    There was also a space to draw a sketch of the river site on this sheet.

  2. 'To what extent does the River Lyn conform to the Bradshaw model of River ...

    it, surface runoff into River, through flow Velocity Increase Load particle size Increase, discharge allows larger size sediment Gradient Decrease, land flattening going downstream Hydraulic radius Increase, due to bigger depth and width of River, so less water is in contact with bed and banks, so there's less friction.

  1. Study the river Cray and see whether the river actually follows a natural path ...

    Normally, a river has the power to carry sediment. If the force of a river drops, the river cannot carry sediment. This is when the river deposits its sediment. There can be much evidence of deposition in a river. Some examples are: 1.

  2. How does the Efficiency and Cross-Sectional Area of a River Change Down Stream?

    working out the wetted perimeter I can use the data with the cross-sectional area to work out the hydraulic radius. The hydraulic radius expresses the losses of energy in overcoming friction with a stream's bed and banks. High values indicate high efficiency, with a channel approaching a semi-circular shape, like

  1. The river Gwaun: Investigating how the course of the river changes from the source ...

    This was an anomalous result and probably happened because the metre ruler slipped between two (large) pieces of bed load. The highest average depth was Site 2, with -36.05, marginally ahead of Site 3 (-34.82) and Site 4(-33.98). The deepest depth was a lot deeper than any other depth because

  2. This project will study about the way the river Conwy in north Wales changes ...

    > WIDHT: To study how the river is wide (width). This is measured in metres. > DEPTH: To study how deep is a river, this is measure in metres. > VELOCITY: To study, how fast the river flowing. This is measured in cubic meters per second.

  1. My hypotheses are:The character of the course of the River Bollin will change along ...

    masses are forced upwards to rise over an obstacle (When air masses reach higher land, the air is forced up and over the obstacle, as the air travels upwards, it is required to loose mass, it achieves this by shedding excess water as rain)

  2. Edexcel Geography B Unit 3 Coursework

    However, in the River Holford, the efficiency is rather poor which is portrayed by the results which are all significantly less than 1.00. The inefficiency is also shown in Pic. 3.1 where the depth is relatively shallow compared to the width which means that there a very high wetted perimeter.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work