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A survey of the river Alyn in Wales

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Introduction

Introduction On Monday 5th of July we went and conducted a survey of the river Alyn in Wales, in Loggerheads. We looked at 4 river sections and did several tests to find the velocity, width and depth of the river we also recorded the sizes of 30 pebbles from each section. We did this to test a number of hypotheses. It took us approximately an hour and a half to arrive there and the weather was bright and warm with little cloud cover, this was quite unexpected because on previous weeks it had been raining. The sites we visited were: (187,575)(188,198)(174,617)(196,629)(please see map on next page) Hypotheses * Is velocity related to depth? * Do the particles in the bedload of a river become more rounded downstream? * Is the pebble size related to discharge? For the first hypothesis I expect to find that the deeper the river the more velocity, I think this because there is going to be more water so therefore more pressure in the river. For my second hypothesis I expect to find that the particles are more rounded down stream because the friction in the river should wear them down more and round them off. And lastly for my third hypothesis I think that the size of the pebble is not related to discharge because discharge ...read more.

Middle

34 20 64 30 51 67 34 44 42 40 39 27 40 37 58 74 90 43 53 32 34 35 40 25 42 41 68 b 17 13 25 21 22 41 28 38 20 24 39 32 34 30 17 30 20 39 40 55 32 43 30 24 25 34 24 15 28 37 c 12 54 34 2 9 20 16 19 20 14 24 12 18 11 7 16 17 26 36 24 13 19 17 13 16 16 8 20 21 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 A 1.5 2.0 3.2 43 80 110 72 51 20 12 7 18 8 7 12 14 18 76 58 60 60 61 31 39 21 53 32 19 54 130 b 1.2 1.1 1.6 15 65 50 38 39 12 7 4 11 6 5 7 6 9 28 39 39 40 26 24 26 14 26 16 9 36 64 c 0.9 0.3 0.7 17 25 45 12 20 5 6 1 7 2 1 5 4 4 18 20 14 29 24 16 16 0.9 0.7 0.4 0.3 11 56 First 30 pebbles at random from the third section of ...read more.

Conclusion

For example the pebble sizes may not be completely correct due to the fact that not all pebbles have been caught in the river's flow (some may have been thrown in there or have recently fallen from the rivers banks.) another factor that caused a problem was with the moel famau stream we visited. The width of the stream was a lot smaller than previous rivers we visited, and therefore made it harder to test velocity (the orange used was too large so we used a bottle cap instead) and also as it was only 2.2 metres wide, we had to convert it into centimetres. Problems such as these are to be expected though and cannot be helped. Factors that could perhaps be helped are things like the tape measure not starting at zero (mentioned earlier) to fix this problem we could perhaps attach string or some other kind of material to the end of the tape and fasten that to the poles instead. Conclusion Revisiting my information I have I have concluded that velocity is not related to depth. I have also proved that particles in the bed load of the river do become more rounded downstream. Finally, I have again proved my theory that discharge is not related to pebble size. ...read more.

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