How well does the River Tillingbourne match the Bradshaw Model?

As you travel further downstream a river, the rivers discharge increases. The water discharge increases as it flows downstream it meets more streams and also collects rain from the increased catchment area.
As you travel further downstream a river, the rivers discharge increases. The water discharge increases as it flows downstream it meets more streams and also collects rain from the increased catchment area.
Channel depth increases downstream. As there is an increased discharge, you have much more energy for erosion, also a larger body of water.
Channel depth increases downstream. As there is an increased discharge, you have much more energy for erosion, also a larger body of water.
The Bradshaw describes how a river's characteristics vary between the upper course and lower course of a river.
Load particle size decreases as you travel downstream. The load the river carries is broken down into smaller material via processes such as attrition.
Load particle size decreases as you travel downstream. The load the river carries is broken down into smaller material via processes such as attrition.

Although we haven’t studied the River Tillingbourne specifically, we have studied the River Severn, which has similar characteristics such as meanders. We should still expect similar features in aspects such as velocity and discharge. It is important to study rivers as it means you can research characteristics of a river, which can be used to gather data for things such as floods, which affect people’s lives drastically.
The River Tillingbourne
The river is located fairly near requiring a straightforward coach journey, meaning for convenience. It’s easily accessible (unlike Rivers such as the Thames, which is too deep and wide to measure) As well as it’s a fairly shallow river, making the means of collecting data much easier (As well as health and safety, so no chance of drowning). We were also given permission to access private land through the FSC. Also, we will be able to have access to secondary data which we can apply to the study.
Background information: The River Tillingbourne runs along the south side of the North Downs and joins the River Wey at Guildford. Its source is near Tilling Springs to the north of Leith Hill (294m Above Sea Level) It confluences at Shalford with the River Wey, which flows into the Thames, which in turn flows into the North sea. The Tillingbourne runs through Friday Street, Abinger Hammer, Gomshall, Shere, and Shalford. The river is 18km in length.
Carrying out the study: we will cover only select parts of the Bradshaw Model and a limited part of the river (5 selected sites) due to the lack of time available within the given timespace and the lack of available resources.
Hypothesis:
The discharge of the River Tillingbourne increases with the distance from the source.

Choosing Site locations and Sampling techniques:
A sample is a representative part of a whole. Various sampling techniques were available to us, but we needed to choose the best sampling method. Out of these were: * Random Sampling: This method of sampling is preferable as it is free of bias, however it was unsuitable as it does not give evenly spread results. * Systematic Sampling: This method is preferable as it gives results in equal intervals, however; in doing so, there are various parts of the River we would have to go to. This posed an issue as many parts were private land or were designated public places (such as parts of a town) * Partly private land (ran through back gardens of people’s homes)
Partly private land (ran through back gardens of people’s homes)
Stratified Sampling: This method was used as it avoids the issues of the previous two, as the sites can be specifically chosen. (Variables such as safety can be applied) as well as the results are in close intervals.
Private Land
Private Land

Source: FSC

Chalk substrates found at Gomshall 1
Chalk substrates found at Gomshall 1

Predominant geology is made of greensand
Predominant geology is made of greensand

Forested areas, which have high levels of interception
Forested areas, which have high levels of interception
River Source: Also various settlements are located here
River Source: Also various settlements are located here
Settlements, mean that there is more run-off into the river, which affect lag times.
Settlements, mean that there is more run-off into the river, which affect lag times.
Designated Public space (cricket field)
Designated Public space (cricket field)

Dorking and Guildford are the nearest towns. (nearest settlement, a lot of impermeable rock, which increases lag time)
Dorking and Guildford are the nearest towns. (nearest settlement, a lot of impermeable rock, which increases lag time)
The River Tillingbourne is located in south east England
The River Tillingbourne is located in south east England

Variable: (what was measured) | Equipment Used: | Method: | Justification: | Limitation/improvements | Width | Measuring Tape | We placed the measuring tape horizontally along one edge of the Bank, to another. | This method is simple and straightforward, and gave the required results. | Certain parts of the bank was hard to measure accurately, due to vegetation getting in the way, or the water was too deep (especially at meandering parts of the river) We were given a limited area to work in, so choosing an alternative location was not an option. We could have taken measurements at a different time of year, with less vegetation. | Velocity | Hydropop Flow meter, Stopwatch | We placed the Hydropop flow meter in the inner, outer and middle edges of the River, and used the Hydropop flow meter to test the velocity. We measured the time taken for the Hydropop meter to come at a halt, using the stopwatch, and then worked out the velocity by dividing over time taken. | The Hydropop flow meter provided a straightforward and accurate means of working out the velocity of the river. The Hydropop is also very portable and easy to use. | The propeller for the Hydropop would not rotate, due to problems with the threading of the screws and the fact that the propeller had to be held at a certain depth not only to work, but to also gain an accurate measurement. Also, in certain parts, there were large rocks put in the way that stemmed the flow of the water, not providing enough water flow to make the propeller spin. We had to clean the propeller and hold it at a certain angle to avoid this. There is also a degree of human error, in the stopwatch being off by a few seconds. Repeating measurements helped reduce this. | Depth | Measuring Tape, Meter Stick | Along the width of the river, the measuring intervals used were (Width/10). Then for every said interval, the measuring stick was placed in the water to measure the depth. Also, the measuring stick had to be placed sideways, as this prevented the water from running up the side of the meter stick. | This method is simple and straightforward, and gave the required results. Also, the meter stick gave accurate results in the depth of water, measuring in centimetres. | Getting an accurate measurement of depth was limited due to there being rocks in the river floor that got in the way of the measuring stick. We could have taken an average of different sites. |

The discrepancy in the water velocity was mainly due to interventions such as large rocks being put in place by children as dams, as well as a bridge which stemmed the flow. F
The discrepancy in the water velocity was mainly due to interventions such as large rocks being put in place by children as dams, as well as a bridge which stemmed the flow. F
OS Map
OS Map
OS Map
OS Map
Abinger Hammer is artificially managed by humans, as it passes through an area of land used as a cricket field. As the width was altered by humans, the depth was inadvertedly increased.
Abinger Hammer is artificially managed by humans, as it passes through an area of land used as a cricket field. As the width was altered by humans, the depth was inadvertedly increased.
The shapes are proportionately representational; therefore, we can see that depth increases as you go downstream
The shapes are proportionately representational; therefore, we can see that depth increases as you go downstream

The part of the river that was flowing through Abinger Hammer was artificially widened and straightened, as it ran through a cricket field
The part of the river that was flowing through Abinger Hammer was artificially widened and straightened, as it ran through a cricket field

Fig. A
Fig. A
Distance from Source (km)
Distance from Source (km)
Velocity
Velocity

The velocity is the speed of the water within the river channel. The graph here shows that, as you travel further down the river, the water velocity increases, as stated by Bradshaw model. However, the average velocity increases only to a certain point (at around 7km from the source, at 0.43m/s) before the velocity decreases at the next recorded interval to 0.33m/s. Gomshall 2 which is artificially managed by humans, is the reason for the high velocity. There is a Culvert which allows water to flow under a pathway, the presence of the culvert alters the river flow.

The velocity is the speed of the water within the river channel. The graph here shows that, as you travel further down the river, the water velocity increases, as stated by Bradshaw model. However, the average velocity increases only to a certain point (at around 7km from the source, at 0.43m/s) before the velocity decreases at the next recorded interval to 0.33m/s. Gomshall 2 which is artificially managed by humans, is the reason for the high velocity. There is a Culvert which allows water to flow under a pathway, the presence of the culvert alters the river flow.

Fig. B
Fig. B

The graph here shows that, as the depth increases, in turn, the velocity increases. The points where the depth decreases, there is also a decrease in the average velocity. Although it is expected that the depth will increase, as you go further downstream, (see figure on Bradshaw model) the river was artificially altered as it flowed near human settlements (parks and back gardens, Shere church was an example of this, see figure 6) The included picture shows a bridge in Shere church, which also stemmed the river flow.
The graph here shows that, as the depth increases, in turn, the velocity increases. The points where the depth decreases, there is also a decrease in the average velocity. Although it is expected that the depth will increase, as you go further downstream, (see figure on Bradshaw model) the river was artificially altered as it flowed near human settlements (parks and back gardens, Shere church was an example of this, see figure 6) The included picture shows a bridge in Shere church, which also stemmed the river flow.

Fig. C
Fig. C

The graph here shows that, as you travel further down the source, the river discharge also increases, as stated in the Bradshaw model. The discharge is calculated by multiplying the cross sectional area by the average velocity. At 4km from the source, we have an anomaly. Crossways farm has a higher river discharge, compared to the other sites visited. This could have been down to the width being very high, as we measured at an angle across a meander
The graph here shows that, as you travel further down the source, the river discharge also increases, as stated in the Bradshaw model. The discharge is calculated by multiplying the cross sectional area by the average velocity. At 4km from the source, we have an anomaly. Crossways farm has a higher river discharge, compared to the other sites visited. This could have been down to the width being very high, as we measured at an angle across a meander

The two pictures show the meander which we measured the discharge, and from the picture, its evident that the river was slightly deeper than other areas, as well as a visible fast current
The two pictures show the meander which we measured the discharge, and from the picture, its evident that the river was slightly deeper than other areas, as well as a visible fast current

Fig. D
Fig. D

This is where Abinger Hammer was located, which was artificially managed by humans. The river was straightened, which resulted in an increased depth.
This is where Abinger Hammer was located, which was artificially managed by humans. The river was straightened, which resulted in an increased depth.
At around 8-9km from the source, we notice a sudden decrease in average depth. Shere church was located here. (see figure 6) which shows large rocks being placed along the river, which affected the depth of the river.
At around 8-9km from the source, we notice a sudden decrease in average depth. Shere church was located here. (see figure 6) which shows large rocks being placed along the river, which affected the depth of the river.
Average Depth compared to distance from source
Average Depth compared to distance from source
The Bradshaw model states that as you travel further downstream, the depth increases. This is shown in the results. Although certain points show discrepancies (average depth does not increase from previous point. (Compare 6km to 8km, which then looking at the map) The line of best fit (linear) indicates an overall increase.
The Bradshaw model states that as you travel further downstream, the depth increases. This is shown in the results. Although certain points show discrepancies (average depth does not increase from previous point. (Compare 6km to 8km, which then looking at the map) The line of best fit (linear) indicates an overall increase.

Fig. E
Fig. E
Width in comparison to distance from source
Width in comparison to distance from source

This graph shows the width of the measured sites, showing their distance from the source. As you can see, there is an obvious increase in width as you travel downstream. This supports the Bradshaw model. The Gomshall sites come up as an anomaly; however this was down to humans altering the river once again. Figure 7 shows a culvert
This graph shows the width of the measured sites, showing their distance from the source. As you can see, there is an obvious increase in width as you travel downstream. This supports the Bradshaw model. The Gomshall sites come up as an anomaly; however this was down to humans altering the river once again. Figure 7 shows a culvert

The shape of the graph, from crossways farm 1, through Gomshall 2, to Shere church, give an idea of the change in Cross Sectional area downstream.

The shape of the graph, from crossways farm 1, through Gomshall 2, to Shere church, give an idea of the change in Cross Sectional area downstream.

Conclusion: 1. Average Depth increases in a downstream direction: Figure D and its analysis suggest that the overall trend supports this statement. This is evident, on the graph, via the line of best fit, as a clear increase in depth is shown. However, we are limited due to discrepancies, where the average depth at various locations actually decreases downstream compared to their previous location. The reason for this can be put down to artificial management, where human interventions have altered parts of the river for various purposes. However, what must be noted, is that the Bradshaw model doesn’t necessarily cover human actions, but instead, natural processes. When looking at the average depth of sites with minimal human intervention, the results support the point (such as looking at both Abinger sites). 2. Width increases in a downstream direction: Figure E and it’s analysis shows that this statement is supported. As you travel further downstream it’s clear that the river width is increasing, which is consistent with the Bradshaw model. However, figure E does outline anomalies, mainly in the Gomshall area, where the width ended up decreasing from the previous location. This is explicitly explained in the analysis, that Gomshall was heavily managed by humans, as the part of the river runs along a cricket field and public park. 3. Average Velocity increases The average velocity is determined by aspects such as the volume of water flowing, the river’s gradient, shape and the friction created by riverbed (including rocks, plants, and possible manmade objects). Looking at figure (A) the general correlation of the graph shows a positive correlation, until a certain point (Gomshall) is reached, where we notice a decrease in the velocity. Figure B explains this very clearly, showing various human interventions, and even natural interventions, such as vegetation. In conclusion our hypothesis was proven correct. The various figures show anomalies which have been accounted for, and explained. It would be extremely beneficial for the investigation, to repeat the study where anomalies have occurred, as areas showing river discharge. However, it must be noted that in certain areas, anomalies have to be expected, especially those areas involving human involvement.

Evaluation: Overall, I am confident in saying that the investigation over the enquiry was successful, as we managed to collect 4 sets of data from 10 select sites in the limited space of time we had available. The data supported the various hypothesis’s we derived from the Bradshaw model. However, what did pose a concern, as well as a limiting factor, was the presence of anomalous results. We however did account for this, and came up with explanations, the main being human error, the limited timespace we had and the fact that the data was collected on different days. Another main factor was not being able to investigate variables such as bedload and geology. In terms of usefulness of the data, this data could be used by other schools working alongside the FSC as secondary data. Also, in theory the data can be used by the local council as a means of monitoring the human effects on the river. Though the small data set may not prove enough. If the investigation were to be repeated, then the main focus would be on investigating the variables which were left out, providing a far more reliable set of results to our enquiry.

Limitation | How it could be resolved: | Visiting only 5 sites | Receiving more funding, and a wider timespace to allow us to stay at the site longer, and thus be able to visit all 10 sites | Difficulty of comparing secondary data to primary, as they were taken on different dates. | Having a longer timespace so that we could stay at the site longer, and collect all required data on the same day. Or perhaps have 2 research groups to gather the data on the same day. | Measuring more variables (as outlined) | Making sure we have the correct equipment, as well as funding to purchase equipment. Also, a more thorough briefing on how to use equipment, to minimise mistakes and error | Taking more measurements | By having more results, we can limit human error and take an average which we can work with, providing better accuracy and reliability. |

Figure 1) Shere Church had concrete panelling along the edges of the river, altering the river width, and thus affecting the cross sectional area.
Figure 1) Shere Church had concrete panelling along the edges of the river, altering the river width, and thus affecting the cross sectional area.

Figure 2) This figure shows the how the edges of the riverbank were affected by human activity. (crossways farm)
Figure 2) This figure shows the how the edges of the riverbank were affected by human activity. (crossways farm)

Figure 3) The meander located in crossways farm. There is visible vegetation as well as the damaged river bank.
Figure 3) The meander located in crossways farm. There is visible vegetation as well as the damaged river bank.

Figure 4)
Figure 4)

Figure 5)
Figure 5)

Figure 6) Large rocks stemmed the flow of the river, affecting recordings of velocity, as well as depth.
Figure 6) Large rocks stemmed the flow of the river, affecting recordings of velocity, as well as depth.
Figure 7) The culvert which stemmed the velocity of the river.
Figure 7) The culvert which stemmed the velocity of the river.
Figure 9) A bridge located at shere church. This is an example of human alterations
Figure 9) A bridge located at shere church. This is an example of human alterations

Figure 8)
Figure 8)