Method |
How it works |
Equipment needed |
Sampling |
Justification |
Limitations |
Velocity of the river |
1) Measure a 5m stretch of the river (length) 2) Drop a dog biscuit into the river and start timing it's journey to the end of the 5m stretch. 3) Work out the velocity using the distance divided by time equation |
Tape measure Stop watch Recording sheets Dog biscuits |
Random stretch of the river was chosen for each group. |
Easy to do Dog biscuits work well because they float and if they are lost then they can just rot down into the ecosystem rather than creating a pollutant. |
through use. Dog biscuits can disintegrate and the darker coloured ones are hard to see in the river. The dog biscuits get stuck on rocks/branches with distorts the findings. Using an impeller just below the surface of the water (where the water runs quickest) gives a more accurate reading |
Measuring bedload of the river |
1) Measure the width of the river and create 5 equally spaced sampling points along the width. 2) Choose the rock that is immediately below the tape measure at each site 3)Use the calipers to measure the height, width and depth of each rock and record. |
Calipers Measuring tape Recording sheet |
Systematic sampling of bedload along a random stretch of river. |
Calipers are better than a meter ruler because they grip the rock to give a more accurate reading. Simple method that collects meaningful data |
If the rock is too big to lift, the data got skewed as a smaller rock nearby was chosen instead. The same person had to do the measuring so there was more consistency about which dimension was which |
Measuring the depth of the cross section of the river |
1) Measure the width of the river and create 5 equally spaced sampling points along the width. 2) Use the metre ruler to measure the depth at each of the sites and record it. |
Measuring tape Metre ruler Recording sheet |
Systematic sampling along the width along a random stretch of river. |
Easy method to use. Collection of enough points to create a cross section graph. |