- Channel Depth:
According to the Bradshaw Model, the channel depth is expected to increase moving downstream from the source.
Like channel width, there is a decrease of 0.11m in the result of the average channel depth between sites 1 and 2, approximately 7KM from source.
This anomaly is due to the abstraction of water from the Calder intake to the Barnacre and Grizedale Lea reservoirs. Hence, this leaves the volume of the water sparse.
Between sites 3 to 5, the channel depth is increases from 0.14 to 0.32m; a total of 0.18m. This increase is because water is constantly added from the River Calder’s 34 tributaries, which increase and connect to the main channel as the river approaches downstream.
The highest increase in water is between sites 4 to 5, 0.19 to 0.32m. This is because River Calder and River Wyre confluence at this point. River Wyre is the dominant tributary of the River Calder, hence why it has added the greatest volumes of water.
- 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.
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 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.
- Gradient:
According to the Bradshaw model the river’s gradient is expected to decrease moving downstream from the source.
The gradient decreases chronologically as one goes downstream from source – from 3.2o to 0.7o; which fits the Bradshaw Model.
The gradient of the river decreases because it is reaching flat, smooth, laminar land which does not contain boulders, which the upper-course has.
Gradient also directly helps to increase the velocity.
This is because an increase in steepness allows a faster flow of water, thence faster turbulent erosion, which breaks boulders by Hydraulic action.
- Discharge:
According to the Bradshaw Model, the Discharge will increase heavily moving downstream from source.
In the Discharge formula, the Cross-sectional Area and the velocity are products; thus as the cross-sectional area or the velocity decrease, so will the Discharge.
There is a significant decrease of 0.802 cumecs in the discharge between sites 1 and 2. This decrease is influenced by the decrease in the cross-sectional area and the velocity.
The cross-sectional area drops by 0.9915 m2 between sites 1 and 2.
This happens because the channel width and depth also decrease heavily between these two sites. The channel width and depth are part of the cross-sectional area formula:
Cross-sectional area = Channel Width x Channel Depth*1
The cross-sectional area gradually increases. Between sites 4 to 5, it increases by 1.0465 m2 because the channel width and depth also increase by a higher amount between those 2 sites.
This is supported by the River Calder’s 34 tributaries constantly adding water; hence why the Discharge also increases between these 2 sites by 0.127 cumecs.
The Discharge is also at its highest because the velocity is its highest at site 1.
This means that, at site 1, the water is travelling at its fastest over a bigger distance.
As both the Velocity and Cross-sectional area drop, so does the Discharge. Discharge is at its highest in site 1 because the cross-section is high, but most importantly, the velocity is at its highest, and it does not increase to that extent thereafter. The drop in the velocity between sites 4 to 5, 0.26 to 0.19 m/sec, is too small to affect the Discharge by a lot, and is compensated by the increase in the area.
- Bed-load size:
According to the Bradshaw Model, the Bed-load size is expected to decrease going downstream.
The bed-load size decreases chronologically as one goes downstream from the source – from 7.6cm to 2.6cm; which fits the Bradshaw Model.
The average Bed-load size between sites 1 and 2 decreases by 0.9cm due to the initial erosion caused by hydraulic-action. This decrease is however minimal in terms of such high discharge of 0.811cumsecs. This is because water is abstracted from River Calder to the Barnacre and Grizedale Lea reservoirs; leaving the supply of water sparse and heavily diminished discharge, as velocity and surface-area have decreased significantly.
Between sites 2-4, the average bed-load decreases heavily by 2.2 cm, this is because water previously abstracted from the River Calder is being added again; therefore this gush of water along with the increases surface-area which it is falling on will increase the erosion by hydraulic-action.
Between sites 4-5 there is a greater load due to the erosion processes in the previous sites. There is a moderate decrease of 1cm. This is mainly due to abrasion which rubs away the rocks’ material against the river bed and moves them creating a greater load; and attrition which slowly wears away the rocks’ material by making them collide against each other.
- Bed-load roundness:
According to the Bradshaw Model, the bed load roundness is expected to increase going downstream.
The bed-load roundness fits the Bradshaw model as it does get rounder moving downstream. For example, there are more angular rocks at the upper-course than at the lower-course and there are more rounded rocks at the lower-course than at the upper-course.
The velocity of the water at site one was 0.67m/sec. This meant that the angular rocks were moved by traction and, because of the heavy gush of the water, were eroded by hydraulic-action; this process is responsible for decreasing the angular rocks between sites 1 and 2 from 55% to 48%. The erosion between these two sites is slow because water has been abstracted to the Barnacre and Grizedale Lea reservoirs.
From Sites 2 to 3, the bed-load roundness changes significantly, this is due to surplus water being re-added to the River Calder. The amount of angular rocks can now decrease because they have already been broadened by Hyraulic-action; they can now smooth by rubbing against the river-bed (abrasion).
Between Sites 3 to 4, there is a significant increase in the number of rounded rocks. This is because the River Calder’s 34 tributaries are adding water. Using this water and the moderate velocity (0.24m/sec), the river can make the sub-angular, middle sized particles, move by Saltation which will make them rounder. This is why the percentage of rounded rocks has increased by 32. However this sight was ambiguous since it was subjective to differentiate between the different types of rocks.
Between Sites 4 to 5, River Calder and River Wyre confluence, adding on huge amounts of additional water. The surface-area in Site 5 is 2.073m2 this means that land will be bigger and smoother; thus there will be less friction. In spite of this, there were still, according to my peers, angular rocks.
