2. YALE NANT MILL VISITOR CENTRE

3. MEET AT NANT MILL VISITOR CENTRE, RHOS BERSE ROAD, COEDPOETH, WREXHAM, CLWYD LL11 3BT. Google Maps or Bing Maps both give good directions! Meet at 9.50 for a 10.00 start. It is unlikely that the toilets/shop will be open at Nant Mill, but we will park at Felin Puleston when we move on to Erdigg and there is a café by the car park. You will need to wear suitable clothing and footwear. Unless the river is dangerously high you will be going in the water….. In other words you need some wellies! We will go out even if it is raining, so be prepared with either waterproof clothing or a change of clothes. It is likely to be cold, so remember to wear plenty of layers! GENERAL INFORMATION…….

4. We will take readings at two sites at Nant Mill.

5. We will visit a meander in Erddig, to take a set of readings. Car Park

6. * Velocity increases with distance from source. * Cross-sectional area increases with distance from source. * As the width of the river increases so does the depth. * There is no significant correlation between the width and depth of the river.

7. * Left bank, right bank …… Left bank Right bank

8. Water flow Which bank is which? Left bank Right bank

9. Water flow And this one? Left bank Right bank

10. * CHANNEL WIDTH – use a tape measure held across the channel from bank to bank on the water surface. * CHANNEL DEPTH – take 10 evenly spaced readings across the channel to measure the depth from the water surface to the stream bed.

11. 1.Width of stream (record, then divide by 9 to get 10 equal measurements for depth readings.) Need to keep tape taut to get accurate measurements Record methodically on a data sheet Width of Channel

12. 1.depth of stream measured at 10 points across the width Need to hold narrow part of ruler into flow to minimise “flex” Record methodically on a data sheet Depth of Channel

13. * VELOCITY - the float method. You need a 10m tape measure, an orange and a stopwatch. * Measure a set distance of the river and mark the start and end points. 10 metres is a good idea - it's long enough to show interesting variation in results, and a round number also makes the maths much easier! * Put the orange in the water slightly upstream of the start point. Using the stopwatch, time how long it takes the orange to move from the start point to the end point. * Repeat this procedure at least three times, placing the orange at regular intervals across the stream so that you measure velocity across the channel. It's pretty likely that at some stage the orange will get stuck in an eddy! Either nudge the orange to move it along or abandon that reading and start again.

14. Velocity data Using a “float” time how long the float takes to travel 10m distance 3 sites along your width – Why? 3 repeats each – Why? Flow Velocity

15. * Yay – we have 2 this year! * Delicate! * Expensive! * Use to check against your “float” measurements * Has to be at a certain depth

16. * Rest impeller base on stream bed. * Mark the water surface level with finger and thumb. * Remove stick from the water keeping surface mark. * Estimate 0.4 of the distance down the stick between the water surface mark and the base. * Place a mark (rubber band) at this point. * Submerge the impeller stick to this point and it will be approximately 0.6 of the depth from the surface down.

17. * Place the flow meter so that the impeller is pointing into the flow of moving water. * You should not rest the impeller on the river bed – it needs to be held at the correct depth (see previous slide). * Flick the switch down to the start position and hold for 60 seconds. * Stop the count (centre position) and not the count value. * Reset by flicking switch to the up position.

18. * You need to convert your flow meter readings from counts per minute to water velocity in m/s. Water Velocity (V) m/s = (0.000854C) + 0.05 This will be done in class when you are checking your data collection!

19. Sampling locations You will use a structured/pragmatic approach to selecting your sampling points along the course of the river. Equal number of sites at the upper and middle/lower sections of the river. This method involves selecting points that are of some distance apart and have safe access to the river (near to the road/accessible and parts that are not too deep or fast flowing). You could have used a systematic method. This would involve choosing sites that are of equal distance apart, but unfortunately some of these sites would have not been accessible or unsafe to take readings. *This method was used when taking depth measurements. Another sampling method you could have used is the random method. This method involves selecting sites using a ‘random number table’. This method also could not be used as it may have ended up choosing sites all near the mouth or near the source and you wanted to spread your sites along the course of the river.

20. * Draw a sketch at each of the sites (it doesn’t matter if your drawing skills aren’t the best!). * Add on a North point, date, time, some idea of scale * ANNOTATE your sketch – this doesn’t mean label, annotation also explain the feature. * Take a photograph of the same area that you have sketched so that you can add extra detail on when you write up your report.

21. * Meander * Cut bank * Water flow direction * Slip-off slope * Inside of meander * Outside of meander * Steep slope * Erosion * Directions NESW * River channel * Ox-bow lake * Deposition * Dimensions (measure it, use a scale) * Direction of view * Date * Location * Break in slope * Area covered by stream when bankfull * Marshy grass * Shape and size of pebbles

22. You will complete one of these per group, per site – so you will end up with 3 per group.

23. * At each field site, you should * Draw an annotated field sketch to show the main features, and for reference back in the class. * Take photographs * Make field notes

24. * What dangers can you think of for this work? * How significant would they be? * Can you prevent any of them? * What would you do in an emergency?

25. Access to the sample site? Fast flowing water Unstable river banks

26. This jeep had just been recovered from the river – the driver had attempted to cross at the forge and the vehicle had been swept downstream!

27. * Think about the hazard (eg. Fast current sweeping you off your feet) and the risk to you (getting wet, cold, drowning) * Likelihood v Severity * Name/phone number etc * And how you would minimise the risks * NB: only related to the investigation (not crossing the road etc) * Remember the risk assessment table that you completed…..once you have been out and collected your data you may be able to fill in some ‘retrospective’ risks!

29. * Section 1 – Introduction * Title, hypotheses and null hypotheses – what are you investigating, what would you expect to find and why. * Map (or maps) showing source of the River Clywedog, each of the data collection sites and where it joins the River Dee. * Background information on the River Clywedog, what has it been used for in the past and what it is used for now. * Bradshaw model – diagram plus explanation of what it shows in relation to depth, width, cross-sectional area and velocity and WHY. * Method – complete method table to explain how you collected your data. * Risk assessment – completed table.

30. Section 2 – Data Collection Describe and explain the sampling techniques that you have used. Include your data collection sheets from the field in the appendix, and a neat copy of results in this part of your report. Make sure that you include reference for all of your secondary data sources (maps, background research etc).

31.  Section 3 – Data Presentation Cross-section for each of the sites Line graph for velocity Scattergraph for width and depth Annotated field sketches for each of the sites Labelled photographs for each of the sites

34. WIDTH (m)DEPTH (cm) 515.7 3.613.2 3.814.3 3.210.9 620.4 516.7 5.916 5.318 7.322.9 3.611.5 7.930.7 6.723.8 3.712.5 3.4213.4 414 4.1815.3 5.7817.5 5.4116.3 4.811.5 4.915.4 6.720.7 6.625.8 6.519.5 6.429.6 Use this data, as well as the data that the class collected, to draw a scattergraph of the relationship between width and depth.

35.  Section 4 – Data Analysis  For each of your data presentation methods (including field sketches) you must write a paragraph describing what is shown.  You then need to analyse the data. Is there a pattern? Are there any anomalies?  Statistical Analysis – Spearman’s Rank Correlation Co- efficient (width and depth).  Look at your scattergraph – is there a connection (or correlation) between the width and depth of the river? Is it positive or negative?  A statistical test called Spearman’s Rank Correlation Co-efficient can be calculated to see how strong the relationship is between these two variables.

36. As temperature rises beer consumption goes up in exact proportion. The hotter it gets the more beer is consumed. This is perfect positive correlation. If you calculated Spearman's Rank Correlation Coefficient (rs) for this data you would get a value of +1 (plus one) What does your scattergraph show?

37. It seems from this graph that the longer you spend doing statistics, the less happy you become. In fact happiness declines in exact proportion as number of hours spent at the statistical grindstone increase. This is perfect negative correlation. If you calculated rs for this pair of variables you would get a value of -1 (minus one)

38. Oddly enough, there appears to be no correlation between these two variables. A change in one appears to have no predicable effect on the other. There is no correlation. If you calculated rs for this pair of variables you would get a value of 0 (zero)

39. Now to work out the test! 1.On your worksheet write out your hypothesis and null hypothesis (this will be that there is no correlation between width and depth of the River Clywedog). 2.Fill in your data for width(x) and depth(y) to complete the 30 sets of data on your worksheet. 3.Rank each piece of width data from lowest (1) to highest (30) 4.Rank each piece of depth data from lowest (1) to highest (30)

40. A small problem occurs if you reach two items of data that are tied (share the same width or depth). Deal with these by sharing the two ranks that the two items of data occupy. E.g. If you have two depth values of 5cm that would share ranks 6 and 7, calculate the average rank: 6 + 7 = 13, 13/2 = 6.5 Each of your 5cm values would have the rank of 6.5. REMEMBER your next value will then be ranked 8. You do the same for multiple ties, add up the appropriate ranks and share them out equally among the tied values.

41. 5.Subtract the rank of depth from the rank of width to get the difference (d) 6.Square the differences (to get rid of any minus figures) 7.Add up the squared differences 8.Now calculate rs from this formula: Where: rs = Spearman's Rank Correlation Coefficient n = Number of pairs of data, Sigma = the sum of

42. The ultimate aim of this test is to be able to reject the null hypothesis and say that there is a significant relationship between the width and depth of the river.

43. If the critical value of rs is above the 5% significance line, you can reject the null hypothesis and say that there is a statistically significant positive/negative correlation between the two variables. In other words, if you did the investigation a large number of times you would expect a different result due to chance only 5% of the time.

45. Section 4 (continued) – Conclusion  Link back to the hypotheses that you set in the introduction.  Summarise your findings.  Does your evidence support the hypotheses of not?  If not, why not?  Does your investigation support the concepts of the Bradshaw Model – explain how.  If not, why do you think this is?

46. Section 4 (continued again) – Evaluation  How effective was your investigation – what worked well? Think about your methodology, the planning of your investigation, the data collected and the conclusions drawn.  What were the limitations?  Issues with the data collection methods?  Problems with equipment?  Problems with accuracy (the level at which the data is exact and free from error) of the data?  Reliability (the extent to which sample data reflects the greater whole) of the data?  How much your conclusions reflected the theory that the investigation was based on (Bradshaw Model).

47.  Suggest improvements or extensions, for example:  Using a better methodology  Improve the equipment used  Repeat the investigation at different times of the year to see if results differed  Repeat the investigation in different locations to compare your results with a similar/different river  Take a larger sample size to improve accuracy and reliability  Taking into account variables other than those looked at in the investigation