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CourseworkHelp
:River Survey
IntroductionOn Monday 28th of September we ventured to Dunston Beck. We went to
Dunston Beck in order to conduct a river study. The undertaking of a river
study was for Geography Coursework that would contribute to our final GCSE
mark. Dunston Beck was not chosen on the spur of the moment but for a
variety of reasons.
The main reason in fact was that Dunston is a relatively local village to
Sleaford. Dunston is just over half way between Sleaford and Lincoln. Due
to Dunston being local this gave us plenty of time to conduct our river
study.
Also the source of Dunston Beck is positioned right on the Lincoln Edge.
A Simple Map of Lincoln Edge and The Geology of Lincolnshire.
Dunston Beck was also chosen because of its array of river features.
Observable Features.
These include:
River cliffs
Meanders
Slip Off Slopes
Slumping
Juncas Grass
Vegetation
Springs
Ox Bow Lakes
Tributary
Old River Channel
Braiding
It was easy to see why Dunston Beck was chosen as it embraced all those
features listed above situated in the same place. It gave us a chance to
test a vast array of hypothesis in the same day. To better Dunston Beck
would be extremely hard. The location of Dunston Beck can be seen clearly
on the following maps.
Aims Of Study.
The aim of our study was to create and test numerous hypotheses. When we
had reached Dunston Beck our main objective was to collect data and to prove
or disprove our hypothesis. By undertaking these tests we were also
learning the methods and the techniques used for the collection of data.
The Following Data was collected:
Surface Width.
Depth.
Wetted Perimeter.
Velocity on the Surface.
Cross Sectional Area.
Discharge.
Bed Load Calibre.
Hydraulic Radius.
Throughout the day we came across a few problems while conducting our
tests. The biggest problem of all was time. We had to be quicker in a few
places but in the end we got all our results down on a recording sheet
accurately. When we were measuring the wetted perimeter we couldn't keep
the tape measure down because there was a disturbance in the river flow, so
we had to wait until it settled and then try again. We did and we ended up
with an accurate result.
Once our data had been collected it had to be presented in such a way that
they would be clear and easily understood incorporating depth and detail.
This is the reason I have chosen to word process all my work. For the
tables I have used a sophisticated spreadsheet programme.
I have created my hypothesis for the data.
Hypothesis.
1. The wider the river the greater the discharge.
2. The speed of the river is slower in areas of vegetation.
3. The greater the velocity, the smaller the particle size.
Method of Survey.
Before any of the techniques we had been shown could go into practice we
needed some equipment. We were given a range of equipment. Once we had
arrived at Dunston Beck we started to use the equipment.
Equipment:
Orange peel
Wellingtons
Disposable gloves
Metre rule
Pen and pencil
Stopwatch
Clipboard
A clear plastic bag
Measuring tape
Orange Peel
I took an orange to the beck. Once we had arrived and set up at our first
station I peeled the orange. This supplied us with many floats. Other
groups only brought a few pieces of orange peel and they either lost it or
the current carried it away. We found that the orange peel was just the
right weight and easy to use because we could see it easily because it
floated just underneath the surface and it wouldn't break up and dissolve.
There was also the added attraction of having a small snack to eat.
Wellingtons
Wellingtons were one of the most invaluable pieces of equipment we brought.
In some places the water was extremely deep and with out them we would have
got very wet. Waders would have been ideal for some of the areas but
unfortunately I was unable to obtain a pair.
Disposable Gloves
Disposable gloves were used to collect the bed load particles from the
riverbeds. Although my hands were covered the water still managed to seep
in. They were mostly used for hygiene purposes, as you never know what you
can dredge up from the riverbed.
Meter Rule
The meter rule was light and easy to transport from station to station. We
used it for measuring the depth and the velocity of the surface water.
Stopwatch
The stopwatch enabled us to time how long the orange peel took to travel
five meters. This enabled us to find the velocity of the surface water.
Measuring Tape
Our group used a recoil measuring tape, as it was small and easy to carry.
Also it was fast at being recalled and this gave us extra time to spend on
our other methods. We used it to measure width and wetted perimeter as well
as the particle size.
A Description Of The Methods Used To Collect The Data.
Surface Width.
Equipment: Tape measure
We measured the surface width by using a tape measure. This was to find
out the width along the beck at the different positions we measured. One
person stood on the left side of the river and one person stood on the right
side of the river. Both of them held the tape measure at the edge of the
banks and measured the distance across the river. I recorded the reading on
my record sheet. The diagram below shows how my group measured the surface
width.
Average Depth.
Equipment: Tape measure, meter rule
Our group worked out the average depth of Dunston Beck. This was done
because we didn't trust the river because it could be deeper in one place
and shallower in another place. We worked the average depth out by
measuring across the beck. The depth was taken every 30cm across the beck
and the tape measure was placed across the beck tightly so that the 30cm
intervals would be accurate. At each position the meter rule was put
vertically into the water until it met the bed. Sometimes the meter ruler
sank into the riverbed and so we had to get it out of the bed and try and do
it again. We did it again because we didn't think it was a fair test. I
then took the readings, which were then recorded onto a recording sheet.
Here is a diagram showing how my group measured the depth.
Wetted Perimeter.
Equipment: Tape measure
Two people out of my group holding a tape measure at the right and left
sides of the river measured the wetted perimeter. Then the tape measure was
stretched from one side of the river to the other. It was laid across the
contours of the bed. This wasn't a very good job to do and luckily I was
the recorder. The tape measure had to be pushed down onto the bottom of the
bed and my friends weren't very happy because they got very wet indeed. The
reading was recorded onto the recording sheet, which is shown in the
Appendix. Here is a diagram below showing how my group measured the wetted
perimeter.
Bed Load.
Equipment: Meter ruler
To calculate this I went into the stream and picked up ten particles in the
right, middle and left parts of the beck. This was randomly done. I did
this by bending down, closing my eyes and putting my hand into the river and
picking up anything that I felt was solid. It was a very wet and disgusting
job as sometimes there wasn't anything there apart from silt. As I didn't
measure the wetted perimeter I was nominated to do this job. As I picked
each of the thirty particles out of the beck they were measured with a ruler
and then recorded onto the recording sheet on page. We then together as a
group took the average of the thirty particles to make the calculation more
accurate. Here is a diagram below showing how we got the bed load
calculation.
Speed.
Equipment: Orange peel, stopwatch, and tape measure
We measured a distance of 5 meters along the stream. Then a piece of
orange peel was dropped into the water at the start of the 5-meter point. A
stopwatch was started once the orange peel had been placed in the water and
the stopwatch was stopped when it reached the distance of 5 meters. This
was repeated another 2 times so that it would be more accurate. We did this
experiment on the left, middle and right side of the Beck. We did it in the
three positions across the stream because we felt that it would be an
accurate result if we did so. We chose to use the orange peel as it was
able to float on the water, it wouldn't break up and dissolve and it was
easy to see because it just floated on underneath the surface of the water.
Sometimes the orange peel got stuck in vegetation. Although the temptation
was to kick it and help it along, we thought that we would disqualify it
from our results because it wasn't a fair test. We repeated the experiment
until it didn't get stuck in the vegetation.
Here is a diagram below showing how we measured the speed of the river flow
along the beck.
Description of Measurement Locations.
We decided to measure location two, six and nine. Below is a brief
description of each location that we measured.
Location Two.
Once we had arrived at Dunston Beck we decided that we would start at the
furthest location away from the gate and work our way down stream as we
went. When we looked around the surrounding area we observed these things.
There seemed to be a substantial amount of vegetation on the both banks. On
the left hand bank there was a steep incline belonging to the railway.
There also seemed to be signs of slumping. There were also overhanging
trees on the left-hand bank and on the right hand bank it was fairly muddy.
The water was very deep in this area and a problem occurred because our
wellingtons were overflowing with water. Other than this everything went
well.
Location 2
Location Six.
We moved down the stream to location six. It is located just before a
tributary. It is well sheltered on the left and right hand banks. There
are glades of trees. It was relatively shallow with its deepest section
only being ten centimetres deep. There were no obstructions in the channel.
The wetted perimeter was larger than station two's. In fact it was 1.4
meters deeper, although the average bed load calibre was smaller.
Everything went well and our wellingtons were not overflowing with water,
which was a relief.
Location 6
Location Nine.
We then moved further down the stream again to location nine. There was a
substantial amount of vegetation in this area. The water was even deeper
than at location two's. In fact the average depth was 27.91 meters. Our
wellingtons were certainly overflowing with water at this location. The
average bed load calibre was equal to location two's. The right and
left-hand banks were steep and very muddy. There were small trees growing
on the left-hand side bank. Everything went well at this location apart
from our feet getting saturated.
Location 9
Hypothesis 1.
Hypothesis.
The Speed Of The River Is Slower In Areas Of Vegetation.
Reasoning:
I expected the speed of the river to be slower in areas of vegetation. My
reasoning for this is because if any material that is moving forward and
something impedes its path it is obviously going to slow down. For instance
when a bullet is fired from a gun it will fly through the air at a
tremendous speed but if a sandbag is placed in its way it is stopped and the
bullets speed is cut drastically due to the atmosphere. It is also the same
as light, once a ray of light enters a new atmosphere such as water it slows
down and bends as each part enters.
Testing:
The method I decided to use to convey my results was a bar chart. Within
this bar chart would be three pairs of columns. Each section would be the
speed at which the river was moving in that particular area of the river.
One would be in an area of vegetation and the other would be where there was
no vegetation. With this it will be easy for the reader to see the clear
comparison.
Results:
The bar chart showed that in the areas of the river where vegetation was
present the speed of the river was slower to that of the section with no
vegetation, which had a faster speed.
Conclusion:
It is easy to see from both my reasoning and the bar chart that in areas of
vegetation the speed of the river was slower than in areas with no
vegetation present. The stations that were used in this result were chosen
just by general selection. I chose half of them, which had little
vegetation, and half that had lots of vegetation. The whole experiment was
really common sense but it had to be proved or else it would have just been
an opinion. The speed of the river is slower in areas of vegetation is true
because my results have proved it.
Hypothesis 2.
Hypothesis.
The Greater The Velocity The Smaller The Particle Size.
Reasoning:
I expected that the greater the velocity the smaller the particle size
would be true. To reinforce my prediction I looked at my notes on the
characteristics of a river. Under this heading was an entire section on how
a river carries its load. There are in fact three ways in which a river can
carry its load:
1. Traction 2. Suspension 3. Saltation 4. Solution
Traction
Traction was the one that concerned me the most. The meaning of traction
is as follows. It is where large fragments contained within rivers flow are
dragged along the bed by the current.
Suspension
Suspension also concerned me as it backed up my hypothesis by showing what
happened at the other extreme. It is where small particles like silt and
clay are held in the water and pulled along by the water current.
Saltation
Sand sized particles bounce along the riverbed in a leap frog movement.
Solution
The lightest of all the loads are the minerals. The minerals are dissolved
by the water and carried along as part of the water.
The diagram below shows how loads are transported down the river.
Combining all four of these methods I felt strongly over the facts and
thought the hypothesis would be true. Just by taking each of the methods
you can see that as the weight drops the particle can be carried.
Testing
The method that I decided to use was the correlation tests. The test I
picked was the scattergraph with the line of best fit. If the points were
all situated around the line then obviously there was a correlation between
all the results. The points used on the graph were collated using a data
summary chart we had produced earlier.
Results
The scattergraph showed no correlation at all between the velocity of the
river and the size of the particles being carried. This may be due to human
experimental error. I also produced a Spearman rank chart and that showed
no correlation as well.
Conclusion
I accept that in my hypothesis, that the velocity of the river is greater
when the particle size is smaller is wrong because of the graphs and charts
that I have produced prove that this is not so. They show no correlation at
all because the results vary a lot. The result that was collected from
location seven was unlike the other results from the other nine stations.
This worried me slightly and I think that if I had repeated my results then
the hypothesis probably would have been true because I think that the
results that I collected were dubious. Also by using my notes and the
definitions of the various ways in which a river can carry its load makes me
even more suspicious of the results. So the results that I collected proved
that the hypothesis was wrong. I also did a Spearman rank chart and this
didn't indicate any correlation between velocity and particle size at all.
So the results that I collected proved that my hypothesis was wrong.
Spearman’s Rank Chart To Show the Correlation between the Velocity and The
Average Particle Size.
Station Velocity X Rank Particle Size Y Rank d d*d
1 0.05 9 4.71 3 6 36
2 0.062 7 2.7 7 0 0
3 0.35 1 2.83 5 -4 16
4 0.207 3 2.58 9 -6 36
5 0.059 8 0 10 -2 4
6 0.08 6 2.65 8 -2 4
7 0.16 5 9.15 1 4 16
8 0.187 4 3.46 4 0 0
9 0.05 9 2.71 6 3 9
10 0.24 2 4.8 2 0 0
Total 121
Working
d x d = 121
6 x 121 726
So R x R = 1- --------- = 1- ----- = 1- 0.733 = 0.267
1000 - 10 990
This Spearman rank chart does not show a positive correlation between the
velocity and the average particle size.
Hypothesis 3.
Hypothesis.
The Wider The River The Greater The Discharge.
Reasoning :
I expected that my hypothesis that stated that the wider the river the
greater the discharge would be true. I based this on facts from my geography
book. It stated that Discharge = the amount of water passing a given point
each second and this is a combination of its volume and velocity. Therefore
I guaged that as the width of the river increased then in turn so would the
amount of water able to pass the point in the same time. Here are a few
basic examples on my hypothesis.
4 Area 24 m2 4
6
4 Area = 48m2 4
12
Testing:
The method I used was to draw cross sections of various stations along with
their discharge reading to show that the stations with the largest widths
would have the biggest discharges. Also shown in a bar chart. I used the
cross sections to show the reader the different widths visually so that they
would be able to see the clear comparison. However there was also the bar
chart to enforce this.
Results:
The cross sections and results accompanied by the data showed that I was
correct and that my hypothesis was right.
Conclusion:
The cross sections show along with their readings that as their width
increases the discharge does. This along with the same cross section of
smaller widths and their smaller readings show the connection. Then the
results of the first test were converted to a bar chart for quick research.
So the hypothesis the wider the river the greater the discharge is true and
I have proven this with my results.
APPENDIX
Calculations
Throughout the river survey we needed to obtain facts and data. We managed
to convert the figures and results into a useful form by using the following
formula:
1. The following formula finds the volume of the river at the point in
question:
Cross sectional area = Width x Average Depth
2. This measures the efficiency of the river channel shape - the degree of
friction holding back the water and the amount of unhindered water. The
higher the HR, the more efficient the channel.
Hydraulic Radius (HR) = Cross sectional area
----------------------
Wetted Perimeter
3. This formula is used to calculate the amount of water passing a given
point in a time period (cubic m /sec).
Discharge = Cross sectional area x Average velocity (cubic m/sec)
Four and five measure the energy of the river.
4. Average Velocity = At surface = sum of surface readings
-------------------------
No. Of surface readings
5. Average Particle size = Total length of particles
---------------------------
No. Of particles
River Study Data
Source Average bed load calibre Surface Width Wetted Perimeter Average Depth
Average Surface Velocity Cross Sectional Area Discharge HydraulicRadius
cm m m m sec/m m2 m3
Location 1 4.71 4 5.5 0.23 0.05 0.92 0.046 0.1672
Location 2 2.7 3.5 3.7 0.23 0.062 0.805 0.05 0.2175
Location 3 2.83 2.85 2.2 0.05 0.35 0.14 0.05 0.0647
Location 4 2.58 4.2 5.4 0.21 0.207 0.88 0.18 0.1522
Location 5 Silt 4.6 5.2 0.31 0.059 1.42 0.08 0.2742
Location 6 2.65 4.2 5.1 0.07 0.08 0.29 0.02 0.0576
Location 7 9.15 5.7 6.3 0.16 0.16 0.91 0.15 0.1447
Location 8 3.46 4.9 5.6 0.23 0.187 1.12 0.21 0.2012
Location 9 2.7 3.6 5 0.27 0.05 0.792 0.04 0.1944
Location 10 4.8 2.5 3.3 0.11 0.24 0.275 0.06 0.0833
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