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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

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Introduction

Introduction I am currently a year 11 pupil at the CBS Grammar in Omagh. As part of my GCSE course I must undertake a field study. 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 because we have studied the theory of rivers in physical geography and because we have easy access to a river. (See planning section) Aims * Use an ordinance survey map to locate a river which we could study * Observe how the river changes * Use equipment to measure how the river changes * Record your findings * Present your findings in a clear and precise manner * Analyse and interpret our results * Make conclusion about our findings and evaluate the study Hypotheses 1. The width of the river increases downstream 2. The depth of the river increases downstream 3. The velocity of the river decreases downstream 4. The gradient of the river decreases downstream 5. The pebble size decreases downstream Spatial Context Map 1 Below is a map of Northern Ireland which shows the location of the Foyle River Basin. This Basin covers parts of County Derry, Tyrone and Donegal. The Pollen Burn is a tributary of the Strule River which is a tributary of the Foyle River Map 2 On the following page I have included an Ordinance Survey extract of the part of the Pollen Burn we studied. ...read more.

Middle

Hence the velocity has remained constant. In the Middle course, the river transports its load mostly in the form of saltation and suspension. Traction is no longer possible, barring exceptional occasions because the energy of the river will have dwindled slightly. Also the river begins depositing its load a small bit in the middle course helping to create some landforms. The features that you would expect to find in the Middle course of a river are: � Meanders � U-shaped valleys � Less steep sides � Slower current Old Age Stage Lower Course As the river enters the final phase of its course, all the changes have been finalised. The river is now very wide ranging from at least 50metres wide to distances much greater. This is due to lateral erosion which uses energy to widen the banks and ignores the bed. For this reason, the river in the Lower course wouldn't be too deep. In the Lower course, the river flows over relatively flat, smooth land which has little or no gradient. This results in a loss of energy. However, the river's velocity will remain constant except in exceptional circumstances such as a flood or alternatively after a landslide which would increase the river's load, slowing it down. The velocity remains steady because the banks and bed of the river are smooth almost removing friction. The lack of friction gives the river in the Lower course a laminar flow. The river in the Lower course transports its load mostly through suspension and solution. ...read more.

Conclusion

4 415 18.7 7 4 3 9 5 680 16 6 5 1 1 6 1050 13 5 8 -3 9 7 1350 13.2 4 7 -3 9 8 1600 11.2 3 10 -7 49 9 1950 20 2 2.5 -0.5 0.25 10 2300 12 1 9 -8 64 Sum D2 265.5 Rs = 1- - 6(sum d�) N(n�-1) Rs = 1- 1593/990 Rs = 1- 1.6 Rs= 0.6 From looking at the table we can prove a strong negative correlation between the two variables. From the graphs on the next page the overall trend shows a decrease in the average pebble size. At stop 2, 4 and 9 this was not the case as the pebble size showed an increase. A negative correlation is proved. Null Hypothesis 5: there is no relationship between bed gradient and distance from the source. Stop Variable 1 Distance from source (m) Variable 2 Bed Gradient (degrees) Rank V1 Rank V2 D D2 1 80 12 10 1 9 81 2 140 11 9 2.5 6.5 42.25 3 280 11 8 2.5 5.5 25.25 4 415 10 7 5 2.5 4.25 5 680 10 6 1.5 1.5 2.25 6 1050 5 5 -1 -1 1 7 1350 3.5 4 -4 -4 16 8 1600 4 3 -4 -4 16 9 1950 3 2 -7 -7 49 10 2300 0.5 1 -9 -9 81 Sum D2 318 Rs = 1- - 6(sum d�) N(n�-1) Rs = 1- 1908/990 Rs = 1- 1.9 Rs= 0.9 There is a significant negative correlation between the two variables. The null hypothesis has been proved Stephen Hackett 12F ...read more.

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