Holford Fieldwork Flashcards
What is a cross sectional area?
An area of the river channel, measured between the riverbed and the river channel sides.
What is river discharge?
The total volume of water flowing through a channel at a given point and is measured in cubic metres per second.
What is attrition?
Where small pebbles and stones collide into each other, becoming smaller and more rounded.
What is solution/corrosion?
Acidic water dissolves rocks
What is a river source?
The area from which water drains into the river.
What is river velocity?
The speed with which the river is flowing, measured in metres per second.
What is a watershed?
A drainage basin boundary.
What is hydraulic action?
Water is forced into cracks on the riverbed and banks by fast flowing water.
What is abrasion?
Where sand and stones are dragged along the bed and banks, acting like sandpaper.
What is the goal of the river fieldwork?
To see how the river changes downstream.
What is the sampling method of the river sampling?
Stratified sampling
Why do we use a stratified sampling method?
We can choose where to sample.
We can choose areas with change significant to the hypothesis.
We can choose an area where geology changes.
How does average width change downstream?
It goes from 0.82 metres to 4.47 metres
How does average depth change downstream?
It goes from 0.05 metres to 0.16 metres
How does the cross sectional area change going downstream?
It goes from 0.039m2 to 0.710m2
How does velocity change downstream?
It goes from 0.253 m/s to 0.540 m/s.
How does discharge change downstream?
0.010 to 0.384 cumecs.
How do we calculate cross sectional area?
Average width x average depth
How do we calculate discharge?
Average velocity x cross sectional area.
How could we improve using the impellor?
We could take more measurements to increase accuracy and to be able to discard anomalies to get close to the true value.
Use a more accurate measuring device like a light gate.
What do we measure with an impellor?
The flow rate of the river.
How do we measure the width and depth of the river?
Use a tape measure to record channel width and record depth with a metre ruler at regular intervals.
How could we improve the quantitative fieldwork method?
Use a more accurate measuring device to reduce paralax error like a lasrer.
Take more readings to get a more accurate average.
How could we increase the reliability of the measurements of the width and depth of the river?
Make sure tape measure was above the water and taut.
Always measure it in the same units.
What limitations were there to the quantitative fieldwork method?
Getting to the other side may be difficult in the lower course.
An island in the middle may distort the result.
What four types of erosion are there?
Hydraulic action
Abrasion
Solution
Attrition
What types of river transport are there?
Traction
Saltation
Suspension
Solution
What is the location of the River Holford?
It is located in Somerset, near Bridgwater.
The source is Lady’s Fountain Spring in the Quantock’s.
The length is 7.2km.
Kilve and Holford are on the river.
Land use is mainly agricultural and urban.
What is the long profile of a river?
It shows how the gradient changes as the river flows from source to mouth through the entire length of a river.
How do we calculate velocity of a river?
Velocity = distance / time.
How do different characteristics change going downstream?
Width increases
Depth increases
Velocity increases
Discharge increases
Gradient decreases
Channel roughness decreases
Sediment size/shape decreases
When was the data collected?
18th March 2024
