Two groups of students were investigating the characteristics of a local river which flowed for 15 km from its source to the sea. They wanted to investigate possible reasons for changes in velocity (speed of flow) downstream. They carried out their fieldwork at five sites along the course of the river. They decided to test the following hypotheses: Hypothesis 1: Velocity increases as the river bed slopes more steeply. Hypothesis 2: Velocity increases as the wetted perimeter of the river channel increases.

1. (a)Before they began the fieldwork their teacher spoke to them about safety in and around the river. Suggest two pieces of advice their teacher could have given them.[2]
2. (b)(i)Name three different pieces of equipment the group would use to carry out their fieldwork at this site.[3]
3. (b)(ii)Calculate the average velocity at site 1 using the results shown in Fig. 10. Show your working and your answer in the box below. [Figure 10.0][3]
4. (b)(iii)When they had completed their measurements at site 1 the two groups compared their results. These results are shown in Table 8 below. [Table 8.0] Suggest two reasons why the results obtained by the two groups were different.[2]
5. (b)(iv)At each site the students also measured the downstream slope (gradient) of the river bed using a clinometer and ranging poles. Photograph B (Insert) shows the measurement being taken. Describe how the students measured the downstream slope.[3]
6. (b)(v)The downstream slope and average velocity results which group B obtained at the five sampling sites are shown in Table 9 below. [Table 9.0] What conclusion would the students have made about Hypothesis 1: Velocity increases as the river bed slopes more steeply? Use evidence from Table 9 to support the conclusion.[3]
7. (c)(i)Complete Fig. 11 below to identify the two different pieces of equipment used to measure the width of the river. [Figure 11.0][2]
8. (c)(ii)The students measured the depth of the river every 0.5m across the channel. Their results for site 1 are shown in Table 10, below. [Table 10.0] Use these results to complete Fig. 12 below, the cross-section of the channel at site 1. [Figure 12.0][2]
9. (c)(iii)Photograph C (Insert) shows how students measured the wetted perimeter of a river. The wetted perimeter is the part of the channel cross-section which the river touches. Their method is described in Fig. 13, below, which is part of a student's fieldwork notebook. [Figure 13.0] The students' results are shown in Table 11 (Insert). Use these results to complete Fig. 14 below by plotting the result for site 1. [Figure 14.0][1]
10. (c)(iv)Do their results support Hypothesis 2: Velocity increases as the wetted perimeter of the river channel increases? Support your conclusion with evidence from Table 11 and Fig. 14.[3]
11. (c)(v)Suggest two disadvantages of their method for measuring the wetted perimeter in a large river.[2]
12. (d)To extend their fieldwork the students investigated the impact of people on the river. State one impact people may have on a river. Describe how the impact could be investigated. Impact of people Investigation[4]

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