Map of Area
List of Apparatus
* Chain
* Clinometer
* Net
* Bucket
* Tape Measure
* Measuring Poles
* Flow Metre
* Ruler (1 metre)
* Dog Biscuits
* Stop Watch
Aims
* To measure the length of the wetted perimeter
* To measure of the river
* To measure the depth of the river at five different intervals
* To study the velocity of the river at five different intervals
* To measure the gradient of the river
* To study the level of pollution in the river
Methods Used
Wetted Perimeter
Measuring the length of the river 4 sites along Afon Conwy 10m sections.
A chain (red) and a tape measure were used to work out the wetted perimeter.
The chain from the water surface on one bank was taken to the opposite bank and the length of the chain was measured.
Measuring the Wetted Perimeter (above)
Width
Measuring the Width (below)
A tape was used to measure the water surface on one bank to the water surface on the other bank. (Hypothesis 1)
Depth
The width of the channel was taken and divided into six. The depth was measured at five different intervals using a 1 metre ruler. (Hypothesis 3)
Velocity
Measuring the Velocity (below)
The width of the channel was taken and divided into six. The flow meter was two-thirds of the way down and timed 30 seconds to see how many revolutions the impeller turned in order to work out the velocity of the river using a flow chart.
Dog biscuits were then used to test the surface velocity of the water. The biscuit was dropped in and timed how long it took to travel 10 meters. (Hypothesis 2)
Gradient
Two poles were used 10 metres apart from each other, and ...
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Velocity
Measuring the Velocity (below)
The width of the channel was taken and divided into six. The flow meter was two-thirds of the way down and timed 30 seconds to see how many revolutions the impeller turned in order to work out the velocity of the river using a flow chart.
Dog biscuits were then used to test the surface velocity of the water. The biscuit was dropped in and timed how long it took to travel 10 meters. (Hypothesis 2)
Gradient
Two poles were used 10 metres apart from each other, and the gradient was measured by a clinometer. (Hypothesis 2)
Pollution
The river was flowing downstream, and the rocks on the river bed were disturbed kick-sampling, so that any creatures underneath the rocks would be carried by the flow of the river into a net. (Hypothesis 6)
Hypothesis
. The width of the river will increase downstream
2. The steeper the gradient the faster the velocity
3. The depth of the river will increase downstream
4. The stone size will decrease downstream
5. The stone roundness will increase downstream
6. Due to more pollution downstream there will be less variety of invertebrate life
Results
All the above 6 graphs are linked to stone roundness. The very angular and angular graphs show a steady decrease in these stones until site 5, and 6. Sub angular stones show a steady increase until site 4 and 5 where there is a massive decrease. Sub rounded stones show a large increase in site 3. Rounded stones show a steady increase up and till site 6 where there is a large decrease in the stones. Well rounded stones show an increase in site 4 and 5. This data does not show a regular pattern, this could be for a variety of reasons such as the river narrowing, slowing the velocity so that Abrasion is less affective. (Hypothesis 5)
The depth of the river increased downstream just as I predicted. (Hypothesis 3)
The width of the river increased downstream also as I
predicted. (Hypothesis 1)
At the start of the river I had a steeper gradient than at the last site of the river, I predicted that the steeper the gradient the faster the velocity but this was proved to be false, I believe it was proved false because of two thing the size and shape of the stones, at site 1 the stones where a lot more angular than they where at site 6 preventing the water to pass through at a fast velocity, also the stones where much smaller at site 6 than at site 1 making it easier for them to roll along the bottom of the river. (Hypothesis 5)
Evaluation
The Velocity - Gradient graph shows a decrease in velocity at Ysbyty Ifan (Site 4) This is because this site has a large wetted perimeter therefore there is more friction on the river bed, also the channel narrows, restricting the flow, decreasing the velocity. Site 4 and site 5 have a greater amount of rounded stones than site 6, which has more angular and sub angular stones which I didn't expect since it was our last site on the river Conwy, site 6 has a high gradient and fast velocity, and was over 37 metres wide. The anomalous results for site 5, 6 lead me to the conclusion that because these sites were secondary data given to us by the field centre and collected by another school, the data may of not been collected properly, it could have been a different time of year therefore altering everything such as velocity, the amount of pollution in the river, the variety of invertebrate life etc. I must express the limitations of the evidence I collected, we only took primary data from 4 sites along the river Conwy, which for a +27km river is not a lot of sites therefore the anomalous results could have been because of certain sites, in a small stretch of river, I would of needed more time, research, and further sites along the Conwy river to get more accurate and meaningful results.