AS Geography Fieldwork Summary

Hypothesis - Our hypothesis for this investigation was the Bradshaw’s Model is an accurate reflection of downstream variation in a number of channel parameters. On the right is an image of the Bradshaw Model. This is relevant to our river studies as the river we visited was a natural river in its middle course. Before we started the investigation I expected that the river would be quite deep due to the heavy rainfall we had before we went, meaning that it would be fast flowing in some places. Because it was deep, it limited the space where we could carry out the investigation, but we were able to find shallow parts and record results so we did have a successful investigation.
< This is silver stream source, as you can see the area is very boggy and not a lot of water flowing. The ground acts as a sponge in this part soaking up the water and storing it. Stones will be quite large here as the water is not strong enough to erode them

< This is silver stream source, as you can see the area is very boggy and not a lot of water flowing. The ground acts as a sponge in this part soaking up the water and storing it. Stones will be quite large here as the water is not strong enough to erode them

Location - The location of our investigation was at Ober Water in the New forest, Brokenhurst. This was our chosen location because it was close to the college, only a forty five minute journey; therefore making it easily accessible. Another reason for this location is because the area is rural which means the river has not been affected by urbanisation, this also means it’s a naturally flowing river. The three parts of the river we measured were all safe locations and there was plenty of room for everyone to get their own results. The map below shows the three exact locations we visited to record the results from the river. When at these places we were measuring channel depth, width, wetted perimeter, velocity and stone samples. We did this multiple times so that our results would be accurate. All locations were very open, had locals walking through, peaceful so it was easy to get on with our work.

^Above is the final location we visited called Whitefield moor. The water was a lot deeper here and there was a clear meander in the middle. River cliffs were a little taller than the ones at Puttles Bridge. This area was very similar to Puttles bridge, but less trees to intercept rainfall explaining why the river here is deeper.

^Above is the final location we visited called Whitefield moor. The water was a lot deeper here and there was a clear meander in the middle. River cliffs were a little taller than the ones at Puttles Bridge. This area was very similar to Puttles bridge, but less trees to intercept rainfall explaining why the river here is deeper.

< This is the view from Puttles Bridge overlooking the main river channel. Behind is where the silver stream joins up with ober water. This is called a tributary. It was muddy in this location but not as bad as the source. Here the water was faster flowing.

< This is the view from Puttles Bridge overlooking the main river channel. Behind is where the silver stream joins up with ober water. This is called a tributary. It was muddy in this location but not as bad as the source. Here the water was faster flowing.

Method - During our time we spent at Puttles Bridge and Whitefield Moor, we had to collect several bits of information about the river. These were the channel depth and width, wetted perimeter, velocity of the river and stone samples. These would help us determine whether or not our hypothesis was true. To collect the data we used primary data collection which means we have done it ourselves and secondary data, which is collected by someone else. One example of primary data we collected was working out the mean depth of the river. To do this we had to measure across the river in small stages, so for example, using a ruler at every 10cm we would record how deep the river was at that point using either a measuring stick or a ruler depending on how deep it was. In this case for the tributary at Puttles bridge we could use a ruler as the water was very shallow. The mean depth for the tributary ended up being 0.0504cm, so not very deep over all, but in other places such as the main channel the mean depth ended up being 14.01cm which is a lot deeper. The type of sampling we used was systematic sampling. This is because our results were recorded at fixed intervals; if they were not then it would not have be an accurate recording and our results would not be fair.

Another type of primary data we collected was measuring the velocity of the river. To do this we used a dog biscuit as a float and set a distance (which was 5m) for it to travel using a tape measure. One person would then place the dog biscuit in the water, another would start the stop watch and wait for it to reach the person at the end of the distance who would then pick it up and pass it back to the first person. This task was done multiple times so that we could have more accurate results when it came to finding out the mean velocity. To calculate the velocity of the river, you have to divide the distance (5m) by the time (seconds) to get the speed, a simple calculation. Again this was systematic sampling as we had set a fixed distance for the dog biscuit to travel. Secondary data is data we have collected from elsewhere such as the internet or a book, therefore an example of secondary data I have collected is the map of the area we were carrying out our investigation.

Quantitative results are collected in numerical fashion, so overall the majority of our results would be quantitative. The channel depth, width and velocity of the river would be an example of quantitative results as they were all recorded down as a number. The final type of data we used was qualitative data which is not expressed in numbers. The sketches of the river we produced at each area would be a good example of qualitative data or even the stone sampling we did as we had to identify what type of stone we had picked up by it up e.g sub angular, rounded ect. The stone sampling was random so that we wouldn’t be biased to one stone and picked up a rounded one because it was easier to identify. Someone from the group would place their foot into the river and pick up a stone next to their foot without looking down. The stone would then be measured, identified and thrown back into the river, we did this multiple times aswell.

Data Presentation and Analysis – For the next couple of pages I have attached graphs and tables which are made from the results we produced. There are graphs for each location we gathered results from. The tables are calculating the hydraulic radius and Spearman’s rank. We use Spearman’s rank because it’s reliable and fairly simple method of testing both the strength and direction of any correlation between two variables. The correlation could either be positive or negative. Our correlation ended up being 0.23527 which turns out to be a positive weak correlation.
This is calculating hydraulic radius;

This is Spearman’s Rank Data Analysis;

All the graphs are the cross section of each area we got our results from and include the mean depth of each place. The final graph is comparing the velocity of the river at each location, therefore we are able to find out which place has the fastest flow of water.

Results/ Conclusion –