Enquiry Process: Introduction --> Methodology --> Data Presentation --> Data Analysis --> Conclusion --> Evaluation
Aim: Studying how rivers change downstream STRATIFIED SYSTEMATIC SAMPLING
Enquiry Question: To investigate whether the River Piddle fits the Bradshaw model
Key questions: Appropriate? YES
1. How does width/depth change downstream? Easy to collect the data for each key question BRADSHAW MODEL
2. How does sediment size change downstream? Able to study the Bradshaw model
3. How does velocity change downstream? You can measure the velocity of the river
Location: Discharge - volume of water passing a point in a second
River Piddle, Site 2+4, Dorset, S of England Load quantity - amount of sediment
Appropriate? YES
Accessible
Relatively safe
Public land
Small river --> manageable
Hazards: Reduced by:
Getting lost from the group Stay in groups of 3-5
Watch where you are walking --> can be slippery Powers Roundess Index
Water
Don't stand in fast flowing areas
Equipment Be sensible --> don’t run with it, don't break it
Weather Wear appropriate clothing
Site 2: Site 3: SECONDARY DATA Site 4:
Width 4.45m Width 11.3m Width 24m Increased Agrees with Bradshaw Model
Mean depth 0.29m Mean depth 0.25m Mean depth 0.38m Increased Agrees with Bradshaw Model
Velocity (Left Bank) 0.06 m/s Velocity (Left Bank) 0.33 m/s Velocity (Left Bank) 0.56 m/s Increased Agrees with Bradshaw Model
Velocity (Middle Bank) 0.2 m/s Velocity (Middle Bank) 0.6 m/s Velocity (Middle Bank) 0.78 m/s Increased Agrees with Bradshaw Model
Velocity (Right Bank) 0.18 m/s Velocity (Right Bank) 0.4 m/s Velocity (Right Bank) 0.53 m/s Increased Agrees with Bradshaw Model
Avg. velocity 0.15 m/s Avg. velocity 0.44 m/s Avg. velocity 0.62 m/s Increased Agrees with Bradshaw Model
Discharge 0.39 m3/s Discharge 1.22 m3/s Discharge 1.68 m3/s Increased Agrees with Bradshaw Model
Avg. sediment size 77.5 mm Avg. sediment size 29.1 mm Avg. sediment size 33.7mm Decreased Agrees with Bradshaw Model
Sediment shape Rounded Sediment shape Sub-angular Sediment shape Sub-rounded n/a
LEARN
Anomaly
, Data Presentation: Primary Data Collection:
Channel Cross Section Depth
Clearly shows the river diagram and whether there was a steep/shallow bank 1. Use a metre ruler, take measurements at regular intervals across the river (30-50cm)
Depth on x-axis + width on y-axis 2. Insert a ruler into the river until it hits the bottom and record the height of the water on the ruler
3. Repeat until the measurements are taken across the whole river
EXAMPLE 4. Record the average
Limitations:
Could be rocks at the bottom
May not be inserted 90 degrees to floor
Misreading numbers - human error
Width
1. Tape measure pulled tight across the river - from bank to bank
Limitations:
Tape measure may be not be pulled completely tight or could get twisted
Velocity
1. Place a flow meter into the river and record the velocity every 10 seconds for a minute
2. Repeat on the left, middle and right of the river
Exam Question Example - evaluate one data collection technique (MS):
Calculate a mean - easy to analyse (1)
Human intervention was needed
Visual representation of river BUT doesn't compare all 4 sites Helped us answer our question (1)
Limitation: weed could get stuck in the flow meter (1)
Field Sketch Limitation: flow meter had to be held perpendicular to the water (1)
See coastal fieldwork Where there was high bank discharge meant that we couldn't sample enough site (1)
Calculations Sediment size
Discharge (cubic metres per second) = cross sectional area (m/s2) x velocity (m/s) 1. At every depth measurement, pick up a stone
Cross sectional area = width (m) x mean depth (m) 2. Take the longest axis (side) measurement with a ruler in mm
Limitations:
Systematic sampling --> random may have been better
Sediment shape
1. Compare the rock to Powers Roundness Index (yellow pic on other page) to decide its roundness
Very subjective - to reduce: come to a group decision
Limitations:
Subjective
Hard to tell difference between how round it is
Aim: Studying how rivers change downstream STRATIFIED SYSTEMATIC SAMPLING
Enquiry Question: To investigate whether the River Piddle fits the Bradshaw model
Key questions: Appropriate? YES
1. How does width/depth change downstream? Easy to collect the data for each key question BRADSHAW MODEL
2. How does sediment size change downstream? Able to study the Bradshaw model
3. How does velocity change downstream? You can measure the velocity of the river
Location: Discharge - volume of water passing a point in a second
River Piddle, Site 2+4, Dorset, S of England Load quantity - amount of sediment
Appropriate? YES
Accessible
Relatively safe
Public land
Small river --> manageable
Hazards: Reduced by:
Getting lost from the group Stay in groups of 3-5
Watch where you are walking --> can be slippery Powers Roundess Index
Water
Don't stand in fast flowing areas
Equipment Be sensible --> don’t run with it, don't break it
Weather Wear appropriate clothing
Site 2: Site 3: SECONDARY DATA Site 4:
Width 4.45m Width 11.3m Width 24m Increased Agrees with Bradshaw Model
Mean depth 0.29m Mean depth 0.25m Mean depth 0.38m Increased Agrees with Bradshaw Model
Velocity (Left Bank) 0.06 m/s Velocity (Left Bank) 0.33 m/s Velocity (Left Bank) 0.56 m/s Increased Agrees with Bradshaw Model
Velocity (Middle Bank) 0.2 m/s Velocity (Middle Bank) 0.6 m/s Velocity (Middle Bank) 0.78 m/s Increased Agrees with Bradshaw Model
Velocity (Right Bank) 0.18 m/s Velocity (Right Bank) 0.4 m/s Velocity (Right Bank) 0.53 m/s Increased Agrees with Bradshaw Model
Avg. velocity 0.15 m/s Avg. velocity 0.44 m/s Avg. velocity 0.62 m/s Increased Agrees with Bradshaw Model
Discharge 0.39 m3/s Discharge 1.22 m3/s Discharge 1.68 m3/s Increased Agrees with Bradshaw Model
Avg. sediment size 77.5 mm Avg. sediment size 29.1 mm Avg. sediment size 33.7mm Decreased Agrees with Bradshaw Model
Sediment shape Rounded Sediment shape Sub-angular Sediment shape Sub-rounded n/a
LEARN
Anomaly
, Data Presentation: Primary Data Collection:
Channel Cross Section Depth
Clearly shows the river diagram and whether there was a steep/shallow bank 1. Use a metre ruler, take measurements at regular intervals across the river (30-50cm)
Depth on x-axis + width on y-axis 2. Insert a ruler into the river until it hits the bottom and record the height of the water on the ruler
3. Repeat until the measurements are taken across the whole river
EXAMPLE 4. Record the average
Limitations:
Could be rocks at the bottom
May not be inserted 90 degrees to floor
Misreading numbers - human error
Width
1. Tape measure pulled tight across the river - from bank to bank
Limitations:
Tape measure may be not be pulled completely tight or could get twisted
Velocity
1. Place a flow meter into the river and record the velocity every 10 seconds for a minute
2. Repeat on the left, middle and right of the river
Exam Question Example - evaluate one data collection technique (MS):
Calculate a mean - easy to analyse (1)
Human intervention was needed
Visual representation of river BUT doesn't compare all 4 sites Helped us answer our question (1)
Limitation: weed could get stuck in the flow meter (1)
Field Sketch Limitation: flow meter had to be held perpendicular to the water (1)
See coastal fieldwork Where there was high bank discharge meant that we couldn't sample enough site (1)
Calculations Sediment size
Discharge (cubic metres per second) = cross sectional area (m/s2) x velocity (m/s) 1. At every depth measurement, pick up a stone
Cross sectional area = width (m) x mean depth (m) 2. Take the longest axis (side) measurement with a ruler in mm
Limitations:
Systematic sampling --> random may have been better
Sediment shape
1. Compare the rock to Powers Roundness Index (yellow pic on other page) to decide its roundness
Very subjective - to reduce: come to a group decision
Limitations:
Subjective
Hard to tell difference between how round it is
