This geographical report will focus on the changes in the characteristics of the River Shuttle as it flows down stream. The River Shuttle is approximately 6.3km in length. It flows from New Eltham (grid reference 443 737, landranger 117 0rdnance survey map), through Bexly where it flows into the River Cray (501 702.)
The aim of this investigation is to test three hypotheses.
1.) The velocity of the river increases as it moves down
2.) Bed load calibre decreases as you move down stream.
3.) There are no significant differences in the channel characteristics of a small river as it moves down
These hypotheses can be tested using several methods. Although the methods used are not completely reliable, due to lack of professional equipment, they can still give a fairly accurate reading for each hypotheses.
Velocity was tested by timing the length it takes for a small and light object to travel over a 5m stretch at each site.
Bed load calibre was tested by measuring five random pebbles from within the river, using callipers and taking an average.
As a way of testing significant differences in the channel characteristics as we moved down stream we measured the depth, width and amount of water of the river channel.
Site one is situated extremely close to the source of the river shuttle. The compass direction of this site is 160 degrees south. Although surrounded by grass land, this section of the river has a moderate amount of pollution due to near by building work.
This section of the river is situated in a woodland area and extremely close to residential housing. A wall has been built as a source of protection from flooding.
The river at this site runs along side a school. There is
This site is found a little further down stream than site three. It runs along side a school. There is little pollution.
The river is situated in woodland area. There is no pollution and evidence of deposition.
Site six is found in a recreational area. There are large amounts of deposition the river has increasingly widened.
This site is found very near site six. It is situated in a recreational area.
Site eight is situated down steam from site seven. Research was carried out on the bend of the river.
This site is found in woodland area and backs on to nearby housing. A barrier has been built to try and protect these houses. There is little evidence of pollution.
The river is situated in a wood-land area so there is little pollution. This site is found near where the River Shuttle joins the River Cray.
Bedload calibre decreases as you move down stream.
The graph above disproves the hypothesis that bed load calibre decreases as you move down stream. There are no patterns, trends or relationships that occur when looking at the average bed load calibre for each site. Site two, for example has an average bed load calibre of 5.0cm. Site ten however has just an average of 3.32cm. This would not normally be expected. The averages vary greatly and there is no significant evidence of an increase or decrease of pebble size.
There are no significant differences in the channel characteristics of a small river as it moves down stream.
This graph shows the width of the river at each of the sites. From looking at this and the cross section of the sites shown earlier I can disprove the hypothesis.
Channel width, distance from left bank and depth of water changes dramatically from site one to ten. The river widens from 3.0m to 10.3m in width from the source and the width continually fluctuates during the route the river travels.
Depth of water tends to increase as the river moves down stream. From photos, data and graphs it is possible to identify significant difference in the channel characteristics of the river shuttle.
The velocity of the river increases as it moves down stream.
This shows the average velocity of the river at each site. With the exception of sites three and ten the velocity increases as the river moves down stream. This proves our hypothesis. The velocity steadily increases from 0.04 meters per second to 0.79 meters per second.
There are several explanations for the outcomes of these hypothesis.
Hypothesis one was proved with the anomalies of sites three and ten. These three sites did not follow the trend that velocity increases as you move down stream. One explanation is that factors such as pollution levels, the situation of the site and the depth of water can affect the velocity. This could be overcome by using more professional equipment to collect our results. Although we took three velocity readings from three different parts of the river and worked out an average, if more readings were taken, the results may have been more accurate.
I expected bedload calibre to decrease as I travelled down stream. There was, however, no trend in bedload calibre size. Although we took a random sample, they were from the same area of the river and this may have affected the results. If we had taken a random sample from five different areas within the site and worked out an average my results may have been more reliable. Also because its such a small river and velocity isn’t extremely high, pebbles on the river floor bed are not as likely to decrease in size as predicted.
Finally, I found that there were significant changes in the river characteristics as we moved down stream. Erosion, weathering and deposition are all factors which affect the characteristics of the River Shuttle and this is shown in the dramatic changes in the shape of land from site one through to site ten.