The students investigated the following hypotheses:
Hypothesis 1: The area of the cross section of the river channel increases downstream.
Hypothesis 2: Average velocity of river flow increases downstream.
The students selected six sites along the river approximately 2 kilometres apart to do their fieldwork.
(i)
In pairs they measured the width of the river channel at each site using a tape measure.
Suggest two things the students could have done to make sure that their results were reliable.
[2]
(ii)
The results of their measurements at each site are shown in Table 1.1.
Plot the result for site 6 on Fig. 1.1 below, which shows how the width of the river channel varies downstream.
[1]
(iii)
At each site the students measured the depth at five points across the channel. The results of their measurements at each site are shown in Table 1.1.
The students drew cross sections of the channel at each site. These are shown in Fig. 1.2 . Use the information in Table 1.1 to complete the cross section and shade in the river channel at site 4.
[3]
(iv)
The method used to calculate the area of the cross section at each site is shown below.
Insert the correct figures from Table 1.1 in the calculation for site 1 below.
[1]
(v)
The results of the students’ calculations of the area of the cross sections are shown in Table 1.2. To what extent do the results support Hypothesis 1: The area of the cross section of the river channel increases downstream? Circle your decision below and support your decision with evidence from Table 1.2 and Fig. 1.2 (below).
completely partially not at all
Table 1.2
[3]
