Geography revision
- Created by: EllaMcNicholl14
- Created on: 16-05-17 18:00
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- Data collection
- Sampling
- used when it large amount of data
- represents feature as a whole
- Random
- no bias, equal chance for each factor
- Systematic
- regular fixed intervals
- disad:only larger samples can be representative of whole width, we only divided by 5
- subject to human error, misreading of measurement
- Ad:representative of whole cross section of river channel
- quick to take samples
- disad:only larger samples can be representative of whole width, we only divided by 5
- regular fixed intervals
- Stratified
- knowing something in adavance, reflects distribution
- Bias
- poor choice of sampling method
- does not represent results, limited data
- size
- depends on complexity of survey
- variety of data, more reliable
- point
- surveys, uses grid
- used when it large amount of data
- Data for river surveys
- primary
- Weaknesses
- human error-susceptible to observer, bias as results are subjective, not objective as you cant generalise the results
- weather conditions-discharge may increase increase in rainy conditions
- not based on full length of the river
- Couldn't see full length of river, made presumptions
- direct and personal investigation, creates anomalies, decreasing reliability
- Strengths
- investigator has full control of variables
- know if it was carried out reliably
- know when and where it was carried out
- up to date
- control over data
- Width/Depth
- measured width in meters with a tape measure, pulled it from left to right bank, making sure it was tight, removed any obstructions, such as vegetation that would affect accuracy
- divided measurement by 5 to get sample points, ensured ruler was touching bottom of river bed at 5 points, recorded data
- systematic sampling
- Systematic
- regular fixed intervals
- disad:only larger samples can be representative of whole width, we only divided by 5
- subject to human error, misreading of measurement
- Ad:representative of whole cross section of river channel
- quick to take samples
- disad:only larger samples can be representative of whole width, we only divided by 5
- regular fixed intervals
- Systematic
- measured width in meters with a tape measure, pulled it from left to right bank, making sure it was tight, removed any obstructions, such as vegetation that would affect accuracy
- Velocity
- Internal velocity: We measured the internal velocity using a hydro prop, we ensured the propeller was twisted all the way to the end of the rod to enable an accurate result, we then timed how long it would for the propeller to make its way to the end of the rod.
- Ad: slightly more reliable, had more control of equipment, quick and easy to carry out
- Disad: the propeller often got stuck, affecting reliability of results, not always clear when the propeller reached end of rod, especially in faster flowing sections of river, subject to misreading of data, vegetation ad our group may act as obstructions, changing river's natural flow
- Surface Velocity: we measured velocity using a cork as a float, we measured out a 10m length of river and measured the time it took the float to cover this distance
- we repeated both test 3 times to gain an accurate finding and identify any outliers
- Ad: this test was easy and efficient to carry out, as we needed minimal equipment
- Disad:subject to human error, the cork often got trapped in surrounding vegetation, affecting results, we may also disrupt the flow if we stood facing the river flow as we would become an obstruction to the rivers natural flow or we could read the measurement wrong. Discharge is also variable in different weather conditions
- Internal velocity: We measured the internal velocity using a hydro prop, we ensured the propeller was twisted all the way to the end of the rod to enable an accurate result, we then timed how long it would for the propeller to make its way to the end of the rod.
- Bedload
- We measured bed load by using a caliper and random sampling, we picked 5 rocks at random from the river at each site we then measured them using the caliper and used a sheet displaying a variation of rock roughness, we then picked which one it matched and recorded our data on either the i pad or data sheet
- Ad: This was again easy and quick to do, due to the fact we had to pick random sampling
- Disad: This was very subjective, as it was qualitative data, it was based heavily on the observer, so was subject to human error. The site had also previously been used by former schools, so the rocks had been placed and thrown back affecting the natural layout of the river
- Weaknesses
- Secondary
- Weaknesses
- don't how its carried out, carried out differently
- may be unreliable and inaccurate
- Weaknesses
- primary
- Quantitative data
- Disad: objective, generalise data easier in comparison to qualitative
- Ad:numerical data, may be more reliable than quantitative, observational
- Study area
- Ad: close to field study centre-easy access to river, river was safe, risk assessment, previous classes visited
- Disad: centre used by lots of different investigators, results may be inaccurate, farmers dredging the rivers will impact the depth, making results unreliable, evapotranspiration doesn't occur in Jan, urbanisation adds to surface run off
- Sampling
- Velocity
- Internal velocity: We measured the internal velocity using a hydro prop, we ensured the propeller was twisted all the way to the end of the rod to enable an accurate result, we then timed how long it would for the propeller to make its way to the end of the rod.
- Ad: slightly more reliable, had more control of equipment, quick and easy to carry out
- Disad: the propeller often got stuck, affecting reliability of results, not always clear when the propeller reached end of rod, especially in faster flowing sections of river, subject to misreading of data, vegetation ad our group may act as obstructions, changing river's natural flow
- Surface Velocity: we measured velocity using a cork as a float, we measured out a 10m length of river and measured the time it took the float to cover this distance
- we repeated both test 3 times to gain an accurate finding and identify any outliers
- Ad: this test was easy and efficient to carry out, as we needed minimal equipment
- Disad:subject to human error, the cork often got trapped in surrounding vegetation, affecting results, we may also disrupt the flow if we stood facing the river flow as we would become an obstruction to the rivers natural flow or we could read the measurement wrong. Discharge is also variable in different weather conditions
- Internal velocity: We measured the internal velocity using a hydro prop, we ensured the propeller was twisted all the way to the end of the rod to enable an accurate result, we then timed how long it would for the propeller to make its way to the end of the rod.
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