Stupid GCSE Geography Rivers coursework!

According to the Bradshaw Model, the channel width is expected to increase moving downstream from the source.


Site Width in meters
Site 1 6.1
Site 2 2.7
Site 3 5.8
Site 4 5.9
Site 5 6.7
There is an abnormal decrease of 3.4m in the channel width between sites 2 and 3; approximately 7KM from source.
This anomaly is due to the abstraction of water from the Calder Intake to the Barnacre and Grizedale Lea reservoirs, grid-reference 5448. A reduce in water will make the channel width narrower. This is because less (lateral) erosion will occur, in-order to deepen the channel.

From sites 3 to 5, the channel gradually re-widens; rising significantly from 2.7m to 6.7m.
This increase happens, especially from site 4 to 5, because River Calder’s 34 tributaries are constantly adding water back to the river; thence increasing erosive processes, mainly hydraulic action and abrasion, widening the channel.

This can be linked to show an overall increase of the Discharge. There will be more water flowing over a wider; deeper channel, because it has greater surface area. The velocity increases because as one moves downstream from the source – there will be less boulders; hence obstacles which initially slow down velocity in-spite of the river being at a greater slope from the source.

(3) Velocity:


According to the Bradshaw Model, the velocity of the water is expected to increase moving downstream from the source.

There is a significant decrease of 0.63m/sec of the velocity between sites 1 and 2.
The speed at site 1 is high because, prior to our arrival at the sites, there were heavy rain-falls (June 10th 2008, near Garstang). Because of this, and the steep gradient the upper-course has; there was a hefty gush of water which rained over a small surface-area at once, allowing water the ability to surpass the ridged wetted perimeter structure, containing large boulders which can slow the velocity.
Site Velocity (m/sec)
Site 1 0.67
Site 2 0.04
Site 3 0.11
Site 4 0.26
Site 5 0.19


However, this significant decrease in velocity between the two sites is caused by the abstraction of water between the two sites from the Calder Intake at to the Barnacre and Grizedale Lea reservoirs at grid-reference 5488. This makes the Channel Width narrower and the flow of water shallower.

There is an increase in the velocity between sites 2 and 3 because some of the water initially abstracted is pumped back into the river; additional water is also added as the river starts to meet its tributaries downstream. This increase continues until site 5, where the speed, from sites 4 to 5, decreases by 0.7 m/sec. This is an anomaly in-term of my hypothesis.
This anomaly can be caused by the confluence of the River Calder and the River Wyre, 300 metres from the A6 Catterall playing fields, at an angle. The river slows down to adjust to this attribute.
There is however an alternative possibility. At site 4 we measured inside the inner-bend of the meander; which flows faster than the outer-bend.