IGCSE Geography River Coursework 2020

« IGCSE Geography River Coursework 2020 Figure 1 – Picture of La Serine By Kajsa van Eldik Mr.

Frank Clarke and Mrs.

Clare McMinn Centre number: CH180 1 Table of contents Introduction ............................................................................................................................................3 Methodology ...........................................................................................................................................5 Data analysis ...........................................................................................................................................9 Site descriptions .........................................................................................................................9 Hypothesis 1 .............................................................................................................................

11 Hypothesis 2 ............................................................................................................................

13 Hypothesis 3 ............................................................................................................................

15 Conclusion ............................................................................................................................................

17 Evaluation ............................................................................................................................................

18 Bibliography .........................................................................................................................................

19 2 Introduction We will investigate different properties of a river according to the Bradshaw Model to answer questions about bedload, discharge, and velocity. This essay is based of an investigation to discover to what extent the river La Serine complies to the Bradshaw Model.

In this paper, we will test three hypotheses to comprehend how they are affected by an increasing distance from the source.

Two of the hypotheses are applied to the Bradshaw model.

However, the third hypothesis is not described by the model and therefore must be described by a different diagram.

The diagrams are explained below. The diagram in Figure 2.1 depicts the Bradshaw Model.

It is a geographical model that describes how a river’s characteristics change as the distance from the source increases.

This model should be able to be applied to all rivers.

The water flows from left to right, the left being upstream and right being downstream. As can be seen the model shows two different sections: the first five spikes which show an increase and the last three spikes which show a decrease. For example, the first spike, discharge, increases as the river flows further away from the source.

On the contrary, the last spike, slope gradient, decreases. In this essay, we will test two hypotheses against the Bradshaw Model.

We also test a third hypothesis which is not described by the model. Figure 2.1 – The Bradshaw Model The diagram in Figure 2.2 is a representation of how different riverbank shapes affect the water velocity.

The fastest flow is located directly above the deepest point in the cross-section. The slowest flow is located along the riverbank. It can be observed that the fastest point is located just below the surface. The diagram can be applied to the third hypothesis. Figure 2.2 – Diagram to show Velocity The three hypotheses are: 1.

Size of bedload will decrease with increasing distance from the source. The Bradshaw Model (Fig 2.1) shows how different river features change as the distance from the source increases.

As can be seen, some features increase and some, like load particle size, decrease as the river flows downstream. The term “bedload” is used to describe the sediment that a river transports, that is too heavy to be carried in suspension. 3 By further looking into load particle size, it can be determined that as the river continues to flow with increasing distance from the source, it diminishes in size. For the first hypothesis, the investigation does not specifically study how the course of a river changes load particle size, but studies how it affects bedload size.

Although they are not the same feature, they both roughly change in the same manner. 2.

Discharge increases with distance from the source. By once again looking at the Bradshaw Model (Fig 2.1), it demonstrates how river features with increasing distance from the source.

A few of these features increase, such as discharge, and others decrease. The term ‘discharge’ is used to describe the amount of water flowing through a river channel at a specific point.

To calculate it, a formula is required (discharge = cross-sectional area x river velocity) and is measured in cubic meters per second, also known as cumecs. By studying the first spike on the model, it can be deduced that as the river continues to run its course, the discharge increases. For the second hypothesis, the investigation examines how the distance from the source affects the river 3.

Surface velocity is slower than the velocity just below the surface. By looking at the diagram to the right (Fig 1) it demonstrates how different riverbanks can affect the river’s velocity.

As can be seen, the fastest point in the river tends to be in the center or by the deepest parts of the river, just below the surface. The term “velocity” is used to describe the speed of the flow of water in a particular direction, to calculate it the formulae (speed = distance / time) is used. By examining the diagram, it can be determined that the slowest points of a river are along the borders of a riverbed and therefore the fastest point would be the farthest away from the riverbanks. This third hypothesis is somewhat different than the previous ones because this is an investigation to determine where velocity is the highest, compared to the others where they are investigations to find out how distance from the source affect them. Figure 2.3 – Map of Switzerland Figure 2.4 – Map of the La Serine area 4 Methodology The methodology is a procedure for approaching and accomplishing a given objective.

In this case, the methodology is a set of procedures that allow the collection of data based around a river.

For each site, different methods were used to measure sediment samples, the cross-section, the surface velocity, and the under-surface velocity.

To collect the data, the following steps were followed. Measuring the bedload Sediments samples are collected and measured to test the first hypothesis; size of bedload will decrease with increasing distance from the source.

By measuring the bedload, it is later possible to process the obtained data to find how bedload size varies between upstream and downstream. 1. As seen in measuring the cross-section, the distance is divided by 10. 2. When measuring the depth, also removed sediment directly Figure 3.1 under the point measured. 3. 4. When bedload has been collected, allocate it the category most alike in the Power Roundness Index. Record it in the table below. Figure 3.2 Figure 3.4 Figure 3.3 6. 5. Then, using a vernier caliper, measure the three-axis seen above. 5 Finally, record the data in the table. Measuring the cross-sections Measuring the cross-section is used to test the second hypothesis; discharge increases with distance from the source.

To calculate the discharge, there are two variables, cross-sectional area and velocity of the water.

By finding the depth of the river, the cross-sectional area can later be calculated. 2. 3. An elastic string is attached to the pegs making sure that its parallel to the water and not hanging.

Do this by using a spirit level. 1. Two pegs are planted on each side of the river. Using a tape measure, lay it along the string and measure its length. Figure 3.5 4. Figure 3.6 5. 8. Starting at the first peg, distance 0, measure the string to the ground. Record all data in table below. 6. Divide that distance by 10 to obtain each tenth of the distance. Then, moving to the first tenth of the distance, first measure the perpendicular distance from string to surface of the water and record data. 7. Having done that, still at the first tenth, measure the distance from string to the riverbed. Figure 3.7 Figure 3.8 6 Measuring the velocity Measuring the velocity is used to test two hypotheses; discharge increases with distance from the source, and surface velocity is slower than the velocity just below the surface. To calculate the discharge in the second hypothesis, two variables are needed: cross-sectional area and velocity.

To calculate the velocity, the surface velocity and under-surface velocity values are summed up and the average is calculated. For the third hypothesis, the surface velocities values are made into an average.

It is then compared against the average calculated from the under-surface velocity. Measuring the surface velocity 1. Taking the cross-sectional point as the middle, measure 2.5 meters upstream and 2.5 meters downstream (5 meters in total).

Marking the start and end. 2. One person will be placed at the start with a cork and one will be placed at the end with a stop clock. 3. The first person will throw the cork upstream and wait until it has passed the starting mark to tell the second person to start the timer. 1. 4. Figure 3.9 5. When the cork has passed the end mark the person will stop the timer. Repeat steps 2 to 4, five times and record in the table. Figure 3.10 7 Measuring the under-surface velocity 1. 2. To measure the velocity under the surface, an impellor like the one on the right is used. One person will hold the impeller, and another will hold a stop clock. 3. The first person will put the impeller into the water and at the same time alert the second person to start the timer. Figure 13 Figure 3.11 4. Figure 3.12 Once the propeller of the impeller has reached the bar it is attached to, the first person will alert the second person to stop the timer. Figure 3.13 5. Figure 3.14 8 Then repeat steps 2 to 4 and record the data. Data analysis Site descriptions: Site 1: At site one, with a longitude of 46.45918°, a latitude of 6.22743° and altitude of 612m, the river was narrow and shallow.

The river measured a total width of only 2.13 meters.

Furthermore, the river was enclosed by very steep banks making the river difficult to access.

The flow of the river was constricted by the load of rocks and sticks blocked on larger boulders. Figure 4.1 – Map showing the location of each site Figure 4.2 – Cross-sectional diagram of the La Serine at site 1 Site 2: At site two, with a longitude of 46.44891°, a latitude of 6.23153° and altitude of 554m, the river was relatively deep.

The river measured a total of 3.64 meters.

The river was still surrounded by steep banks, but it was more accessible than site one.

The bedload was smaller in comparison to site one.

It was possible to hear a waterfall in the distance. Figure 4.3 – Cross-sectional diagram of the La Serine at site 2 9 Site 3: At site three, with a longitude of 46.44083°, a latitude of 6.24157° and altitude of 468m, the river was wide but shallow.

The river now measured a total of 4.9 meters.

The river is more accessible than at the two other sites.

The bedload is regressively smaller than the two other sites.

The waterfall can still be heard but it is louder, insinuating its closer which could have caused an increased rate of erosion within the bedload. Figure 4.4 – Cross-sectional diagram of the La Serine at site 3 Site 4: At site four, with a longitude of 46.42986°, a latitude of 6.24684° and altitude of 427m, the river was still wide and shallow.

The total boast of the river is 7.27 meters.

The banks surrounding the river were relatively flat.

There is a variety of different sized bedload, but it is smaller than at any other site.

The waterfall can still be heard but at a distance. Figure 4.5 – Cross-sectional diagram of the La Serine at site 4 Site 5: At site five, with a longitude of 46.41923°, a latitude of 6.26358° and altitude of 396m, the river was yet again wide and shallow.

The total boast of the river is 8.57 meters, it is the widest measured.

The banks are rocky with very little human interference but is still easy to access.

The waterfall can no longer be heard. Figure 4.6 – Cross-sectional diagram of the La Serine at site 5 10 Hypothesis 1: Size of bedload will decrease with increasing distance from the source. Data collation: To collate the data for the graph of the first hypothesis, the mean between 10 rock samples (can be seen how this was collected in the methodology) is calculated for each of the five sites as well as their standard deviation. Site 1 2 3 4 5 Mean Standard deviation 4,38 0,89 3,72 1,16 2,23 0,61 2,06 1,02 1,95 0,35 Analyzing data: Describing data: By looking at the graph, it is possible to see that the trend is negative.

The graph shows that as the sites get farther away from the source (the source being zero on the graph), the size of bedload decreases. Figure 5.1 – Graph for the first hypothesis Describing anomalies: Although the graph does not particularly show any anomalies, however, not all points lie directly on the trendline.

By looking at the graph, it is possible to see that the points at site 1 and 2 have a steeper gradient, they have a window of 0,66.

However, the last three sites have a gentler gradient and have a window of 0,28.

The window shows that there is a bigger difference in the points of site 1 and 2 that that of the points of site 3 to site 5. Explaining data: Not only by looking at the Bradshaw Model, where it can be estimated that bedload diminishes in size as it is transported by the river.

But also, by justifying and backing it with Year 10 knowledge.

By recalling “River Transport and Deposition”, it can be determined that river transport influences bedload size.

There are 4 types of river transport: solution, suspension, Figure 5.2 – Diagram to show different types of river transport saltation, and traction (SSST).

However, in the case of our first hypothesis, only saltation and traction are relevant. 11 The term “saltation” is used to describe another manner of transportation where rocks are bounced along the riverbed.

It incorporates stones that are too light to be rolled along the riverbed but too heavy to be transported in suspension.

These small stones and pebbles are therefore bounced along the riverbed in a “leap-frog” motion. The term “traction” is used to describe a manner of river transportation.

It consists of the heaviest materials in a river, such as boulders and large stones, which are rolled along the riverbed by the river flow.

Traction requires the most energy out of the 4 types of transport. The larger stones in traction therefore move slower, whilst smaller stones move faster therefore allowing them to go further from the source.

This causes the larger rocks to be deposed upstream and the smaller ones to be deposed more downstream. Another reason that causes the size of bedload to decrease with an increasing distance from the source is that of erosion.

When stones are transported by saltation and traction they do not only bounce and roll.... »