Physical Flashcards
What was the physical geography enquiry?
How does the depth and river load change across the bend of a river?
What was the physical geography hypothesis?
• The river is deeper on the outside bend than the inside
• The river load is larger on the inside bend than the outside
What were the reasons for the physical geography hypothesis?
-The river should be deeper on the outside bend than the inside bend as there is more erosion taking place because the river has the most energy here due to decreased friction
-The river load should be larger on the inside bend of the river as there is less erosion taking place and more deposition. This is because
What did we do collect the data for our physical enquiry?
1)The width of the river was measured using a tape measure from one bank to the opposite bank where the water met.
2)The tape was kept straight and tight, ensuring a measurement directly across the water’s surface.
3)Ten depth measurements were taken across the river to capture variations in depth.
4)The total width measurement was divided by 10 to establish equally spaced points across the river.
5)These 80cm intervals were used to measure both depth and the size of the river’s load.
6)Depth was measured using a meter ruler from the water’s surface to the riverbed in centimeters.
7)For the load size, samples were randomly selected within each 80cm interval, and their long axis was measured with a caliper in millimeters.
8)A sediment analysis was conducted to determine the shape and type of the riverbed load.
How did we present our findings for the depth of the river?
-we created a cross section of the river using a line graph to compare the width and the depth to identify patterns and to see if the river depth was deeper on the outside bank just as the hypothesis predicted
-We found that overall, the depth increases from the inside bank to the outside bank of the river e.g. on the inside bank the depth starts at 2cm, whereas, on the most outer bank of the river the depth is 38cm An anomaly is that the deepest point of the river is not the most outer bank, it is at measurement site 8/10 measuring at 42cm in depth
How did we present our findings for the sediment analysis?
-we produced a scatter graph using averages of the longest axis of three pieces of sediment at each interval to improve accuracy
-We found that overall, there is a negative correlation between the depth of the river and the mean sediment size e.g. the river is the deepest on the outer bank of the river and the graph shows sediment size decreases from the inner (675mm) to outer bank (50mm)
An anomaly is that the biggest sediment size wasn’t found on the inner bank (site 1), it was found at site 7/10 and measured at 750mm
How did we present our findings for the sediment roundness?
-We designed pictograms to represent each stage of the power index of roundness and added them to the river cross section on the graph.
-Our drawings were subjective and difficult to keep consistent
-Overall, the data shows that roundness increased from the inner to outer bank e.g. sediment found on the inner bank of the river measured at 3/6 on a roundness scale (angular to round), whereas, on the outer bank it measured at 4/6. There was an anomaly as the most round sediment was found in the middle of the river rating 5/6 on the scale
What proof is there to support the findings?
The depth of the river is in line with geographical theory that the river is the deepest on the outside bend and shallowest on the inside bend and helps explain the formation of the meander
The size of the sediment was in line with geographical theory that the sediment will be smallest on the outer bend of a river because there is more erosion happening here as it is deepest, has less friction and the fastest flow is found here. It also made sense it was smallest in the inside bend as there is less erosion there and friction is slowest.
The size of the with geographical theory that the sediment will be smallest on the outer bend of a river because there is more erosion happening here as it is deepest, has less friction and the fastest flow is found here. It also makes sense that the sediment is smallest on the inside bend as there is less erosion and more deposition happening here as it is shallower, there’s more friction and the flow is the slowest.
Was the hypothesis correct?
I found that my hypothesis was correct. The results show that it was deepest on the outside bend of the river. The inside bend of the river was as little as 2cm deep at site 1 - ranging to 33cm at site 5. Sites 6-10 were all deeper than the measurements from sites 1-5. At the outer bend, the depth reached 44cm at its deepest point (site 8) which demonstrates clearly that the outer bend is deeper than the inner bend.
the riverbed sediment was mostly largest on the inside bend with relatively large measurements such as 678mm and 562mm, compared to the outside bend where measurements included 87mm and 91mm. This demonstrates that on average, the sediment size measured along the longest axis of three pieces of bedload and an average was taken was larger on the inner bend than the outer bend as expected.
How might the way we sampled the results have brought error?
-The sample was done once so it wasn’t reliable.
-It was a small sample of one part of the river so wasn’t representative of the whole river.
How might have the use of equipment impacted the quality of results?
1)Depth measurements were prone to human error as we used a meter ruler and our eyes, but we had at least 2 students read each depth for better accuracy.
2)Sediment size measurements with a caliper could have been affected by human error, so having students double-check would have helped.
3)The roundness scale had only 6 choices, limiting accuracy; more options would have been better.
