Paper 3: Physical Enquiry

Question 1

Why is this a suitable hypothesis for a geographical investigation:

Answer 1

Meanders are a distinctive and common river landform found along the middle course of a river. Investigating river velocity and channel depth will help prove that the expected river processes (erosion on the outer bend, deposition on the inner bend) are occurring.

Question 2

Why was the location of the Ingrebourne River a suitable location for a study area:

Answer 2

The Ingrebourne River has two safely accessible meanders nearby, allowing us to collect data from 2 sites (a broader data set). The depth and flow was safe enough for students to enter and conduct measurements making it a good location to collect data safely. The Ingrebourne River is also a 40 minute tube journey away from school so it is in an accessible location. The short journey time also meant we could spend longer there, investigating the meanders

Question 3

Getting lost using public transport

Answer 3

Students clearly briefed on the route. Students travel in small groups with a member of staff and get on and off public transport as instructed.

Question 4

Danger crossing roads on route to the river site

Answer 4

Teachers deliberately selected a site with many pedestrianised areas and safe crossings.
Cross roads only at a crossing, when it is safe to do so and in groups

Question 5

Working in a river

Answer 5

Teachers deliberately selected a rivers site where the meanders were shallow and velocity was low enough for students to collect data safely to reduce risk of drowning.
Students were instructed to wear wellington boots to avoid slipping on the uneven river bed.
Students briefed about the risk of infection working in open water and covered cuts with plasters and used hand gel after each activity.

Question 6

Channel cross profile
How was the data collected

Answer 6

Students worked in groups, using a measuring tape to measure width and metre rulers to measure depth at regular distances across the channel. This helped us measure the cross-section

Question 7

Channel cross profile
Advantages of data collection

Answer 7

The meander channel cross profile (width and depth) was quickly measured and the data recorded on a table that made interpretation very easy.
Changes across the river channel were easy to see.

Question 8

Channel cross profile
Disadvantages of data collection

Answer 8

Having a number of groups working at the same time trampling across the muddy river bed, may have slightly changed the depth in different places making the results less accurate.
Only two meanders along the river were selected and these were chosen because they were safe, accessible and very close together. The findings may not reflect less accessible meanders along other parts of the river course.

Question 9

Channel cross profile
Possible improvements

Answer 9

If we had more time we could have had fewer groups working at one time, or have spread out over a greater number of meanders. This would reduce the likelihood of feet trampling the soft riverbed and altering the cross profile. However we are generally confident with our findings as all groups’ data showed a significantly deeper outer bend, supporting the hypothesis.
More time would have allowed us to visit more meanders at different points along the middle and lower course of the river. This would give a wider range of data sets and perhaps reveal more contrasts in channel shape. However we were able to contrast two meanders, and the findings are consistent with what we expected (the meanders were deeper on the outside bend

Question 10

velocity (speed of the river) measurements
How was the data collected

Answer 10

Students measured a 3 metre distance along the outside bend, the middle of the river and on the inside bend. A float was dropped into the river and we timed how long it took to travel 3 metres. The measurements were completed 3 times and an average velocity measurement was calculated for the outside, middle and inside bend.

Question 11

velocity (speed of the river) measurements
Advantages of data collection

Answer 11

Data can be collected quickly and easily. The equipment used (satsuma float, phone timers) was easy to manage and the data could be easily recorded on a table.
Taking multiple timings and calculating an average reduces the influence of anomalies and makes the findings more reliable.

Question 12

velocity (speed of the river) measurements
Disadvantages of data collection

Answer 12

Multiple groups were working in the river at the same time, creating obstacles for the river current. This meant the flow of the water was disrupted as it moved downstream. This could lead to slower velocity compared to a quieter day with no visitors.
The depth of water was low at times meaning the float (satsuma) got stuck or students were tempted to move away from the edges of the meander to get a better flow. The data might lack some accuracy, and make velocity seem faster than it was.
Students based their judgements on a snapshot view of the velocity of the river in one day on a dry month during the summer. At other times of year the flow might vary considerably e.g. after heavy rain it could be faster.

Question 13

velocity (speed of the river) measurements
Possible improvements

Answer 13

We could have used more sophisticated equipment e.g. a flowmeter, to get more accurate data; water flows through this device and gives a velocity reading. This would overcome inaccuracies caused by the float getting stuck.

If our groups were smaller there would be fewer students in the river, reducing the chance of human obstacles interrupting the flow. This would have improved data accuracy.

Velocity data would have been more reliable if we visited several times at different points during the year with varying levels of rainfall. If we also had data for a wetter, winter month (when discharge and velocity is greater) we could calculate an average velocity for the year. This data would be more reliable/representative.

However on both meanders there was a considerable difference in velocity in the outside and inside bend suggesting overall velocity is faster on the outside bend.

Question 14

velocity (speed of the river) measurements
data presentation

Answer 14

The located bars showing the average velocity measurement for the outside, middle course and inside bend were very different in size showing a much faster velocity on the outside bend than the inside bend.

Question 15

velocity (speed of the river) measurements
data presentation cons

Answer 15

Limitations: The located graphs show an average velocity measurement, therefore it gives us an overall picture of velocity across the channel but does not show variations or anomalies within the data sets.

Question 16

Channel cross profile diagram: data presentation

Answer 16

The cross-profile line graph shows river width and depth from a sideways perspective. This makes it easy to see how the channel changes from the outside to the inside bend. The outside bend was clearly deeper for both meanders.

Question 17

Channel cross profile diagram: data presentation cons

Answer 17

Limitations: The scale used to show depth in centimetres was different to the scale used to show width in metres which made the river look deeper than it was. However as long as the scale was read correctly the overall change in depth across the meander was still easy to see and understand.
We only measured the depth of the river at fixed intervals, so the cross-profile shape doesn’t perfectly match the actual meander’s shape.

Question 18

Mapped channel cross profiles and velocity bars (2 methods combined)

Answer 18

Mapping the velocity bars onto the cross profile diagram allowed us to observe patterns and make links between the two data sets. For example, in meander 1, the depth was particularly deep in the outer bend and middle of the river compared to the inside bend. The velocity data was similarly fast in both the outside and middle bend, and the inside bend was significantly slower. This clearly demonstrated where the river was deeper, less friction meant the velocity was faster.

Question 19

Channel cross profile diagram: data presentation

Alternative presentation method:

Answer 19

Alternative presentation method: Negative bar graph (bars go downwards to show depth

Question 20

Channel cross profile diagram: data presentation
Alternative presentation method: pros

Answer 20

Advantages: It would be easy to read the depth of the river and specific points across the river meander profile.

Question 21

Channel cross profile diagram: data presentation cons
Alternative presentation method:

Answer 21

Disadvantages
Hard to see the overall profile/shape of the river channel and how it changes in shape from the outside to the inside bend, making it harder to interpret the data.

Question 22

Velocity data Alternative presentation method:

Answer 22

Proportional flow arrow

Question 23

Velocity data Alternative presentation method: pros

Answer 23

Advantages: The arrows overall width is proportional. It might be easier to contrast than the bars. Arrows can also indicate direction of the river current.

Question 24

Velocity data Alternative presentation method: pros

Answer 24

Disadvantages: The arrow would increase in width according to seconds taken to travel. As a result the slower flow would result in a wider arrow that would appear to indicate a higher value. This would be very confusing to interpret. Furthermore, flow arrows are more difficult to draw and read accurately. Human error could therefore make analysis inaccurate.

Question 25

Channel cross profile:
.What did the results show?

Answer 25

On both meanders the data clearly showed that the outside bend was significantly deeper than the inside bend. Although meander 1 was wider and deeper, on both meanders the outside bend was approximately 3 times as deep as the inside bend. In meander 1, the middle course of the river was also significantly deeper than the inside bend; this was not the case in meander 2

Question 26

Velocity data:
What did the results show?

Answer 26

Despite a few outliers, the average velocity was significantly faster on the outside bend compared to the inside bend on both meanders,
Although inner/outer bend velocity contrasted for both meanders, there was a much more significant difference across meander 1.

Question 27

To what extent did the results support the conclusion?
Channel cross profile diagram:

Answer 27

On both meanders the outside bend was approximately 3 times as deep as the inside bend clearly indicating the river current hitting the outside bend increased erosion making the meander deeper. The inside bend was significantly shallower with noticeable deposition of material.

Question 28

Overall Conclusion:

Answer 28

The data clearly showed that the outside bend of a meander is deeper and has a faster velocity. Even with a few inaccuracies and anomalies, average figures showed that this pattern was clearly visible for both meanders we visited.

Question 29

To what extent did the results support the conclusion?
Located velocity bars:

Answer 29

On both meanders the flow was clearly faster on the outside compared to the inside bend proving the hypothesis. The deeper channel on the outside bend has reduced friction allowing the water to flow faster.