Physical

• Accuracy


  how close a measurement is to the true value
• validity


  the relevancy of the measurements to the study
• precise


  the smallest scale of measurement on the equipment used
• representative


  how typical your sample is of the whole area
• limitations


  now time, location and resource use could be improved next time
• bias


  how data might be affected by someone's opinion
• primary data


  information that you collect yourself eg. tallies, measurements and photographs
• Secondary data


  information that someone else has previously collected and made available eg. on the internet
• systematic sampling


  equal intervals between each point
• random sampling


  every point has an equal chance of being picked
• stratified sampling


  taking a representative number of measurements in each area
• pros of systematic sampling

  - simple and easy to follow

  - shows change over space or time well
• cons of systematic sampling

  - can give inaccessible an unsafe fieldwork locations

  - may miss smaller patterns
• pros of random sampling

  - unbiased strategy

  - works well in homogenous areas (that are the same)
• Cons of random sampling

  - samples can be clustered together and not representative

  - Can give inaccessible or unsafe locations
• pros of stratified sampling

  - valid data from accessible locations

  - can be combined with the others
• cons of stratified sampling

  - bias sampling sampling

  - can be more time consuming to set up
• two locations we went to in the river

  Cossway Farm and Abinger Hammer
• Title/ Theory

  Change in River Tillingbourne

  A river gets deeper, wider and faster as it goes downstream
• Why was this a good question?

  - know from geographical theory that rivers change as they go downstream

  - good scale and focus; it's answerable in a day

  - we were able to collect appropriate data

  - clear geographical links
• How was your chosen location appropriate (access wise)?

  - close to the A25 so easy to get to

  - easy to get help if needed
• How was your chosen location appropriate (scale of river wise)?

  19km long → quick to see changes in the river avena short distance

  small drainage basin 59km squared → lower flood risk, safer
• main investigation question


  How does the river change as we go downstream?
• sub-investigation questions


  How does the width change?

  How does the depth change?

  How does the speed of water change?
• Why did we do a field sketch?

  - visually represents the data and the location of the site

  - gives an appreciation of the data

  - easy to identify important features of the landscape

  - easy to refer back to
• Why did we annotate a photograph

  - more accurate than a sketch

  - highlights the key features of the location

  -easy to refer back to when analysing data
• when measuring the width of the river


  what: used a tape measure to record the width of the river at each location. we did this once at each location

  sampling -stratified: done at one location, decided by accessibility and distance down the river

  Why: we know that river width is one of the things that changes as a river flows downstream

  positives: ACCURATE - tape was pulled as tight as possible

  - measure to the point directly opposite

  - measure across the surface by crouching down

  negatives : overhanging trees can interfere with data and meanders may make it harder to judge what point is directly opposite
• measuring depth of the river

  what: uses metre stick at 4 points along the width of river

  sampling - systematic: divided width of river by 4 so it was measured at 4 equal intervals

  Why: we know that the river depth is one of the things that changes as a river flows downstream

  positives : reliable as repeated 4x and appropriate for the question we had

  negatives: metre stick may not always have been straight or vegetation on river bed may interfere
• measuring velocity of the river

  What: used hydroprop, timed using stop watch how long it took for propeller reach the end of the stick and then divided by 3 to work out the velocity to match the length of the stick

  sampling - random: placed at random points in the river

  why: to measurethe river velocity as we know it changes based on the river

  positives : more accurate than using a cork and stopwatch makes numbers reliable

  negatives : can be hard to see the propeller and meanders can affect the speed of the water
• water risk assessment


  risks: drowning, dirty water, Weil 's disease

  reduce: always staying in groups at all times and not getting into the river with open wounds
• uneven surfaces risk assessment

  risks: slips, trips, falls

  reduce: sensible clothing and footwear
• ticks risk assessment


  risks: Lymes disease

  reduce: long clothes, covered skin
• width of river data presentation → Bar Chart

  - plotted with data against the 2 locations

  - easily comparable to see which was largest and smallest

  - discreate data in categories which are separate and different

  - used bar chart not pie chart as we were interested in the quantity not the proportion of the width

  improvement: we could have put the bars onto a map with proportional bars to see changes over space
• depth of river data presentation → line graph

  - used line graph, plotting depth against 4 sample locations

  - continuous data which is change over space, so that the line could show us the change

  - we could visualise the shape of the river bed

  - allowed for easy comparison, able to visualise the data

  - axis were clearly visible so we could see anomalies

  improvement: only showed 4 pieces of data, so a trend may not be clear
• velocity of the river data presentions

  - we showed the data geolocated so that it was easy to compare over spaces

  - the circles were bigger if the velocity was stronger so it was easier to draw to comparative conclusions

  - discreate data, so we could see them separately

  improvement : Only one set of data so does not show variation within data set and does not tell us the exact values
• width


  reliable: only one sampling locations so not enough data. done randomly so may not be representative

  accuracy: the limit human error we pulled tape tightly, measured point directly opposite and across the surface by crouching and tape measure was precise (mm)

  validity: able to compare 2 sites
• depth


  reliable: did 4x and sampled randomly so decreases reliability as place may not be representative

  accuracy: precise as metre stick is mad. weather good so all sticks were visible. rushed so results not recorded carefully

  validity: able to investigate in 2 places (appropriate to question)
• Velocity


  reliable: location on meander so speed varies around a meander due to the thalweg - should have taken multiple readings

  accuracy: difficult to see hydroprop and human error in the stop watch recordings affecting accuracy

  validity : very valid as taking velocity readings enables us to work out discharge
• Reliability 


  consistency of results ans conclusions. Results will be similar if repeated