River Holford field work (paper 3) Flashcards
what is the fieldwork title for this assessment
investigating downstream change on the river Holford
what is your hypothesis for this assessment
- discharge will increase with distance downstream on the river holdford because more tributries join to creater a larger river so more water
- velocity will increase with distance downstream on the river Holford because more water and energy with a bigger channel means less friction so water moves more freely
- cross-section area will increase as we move down stream
how long is the river Holford
8km
describe the geologies of the river Holford in the upper, middle and lower courses
- upper = sandstone
- midde = mudstone
- lower = limestone
explain the advantage of the fieldwork location used for your enquiry
- accessibly - mainroad ~ A39
- we can walk along it - good idea of change in a timely manner ~ small river
- accessable car park
- previous schools hae studied here so it was safe and legal to do so
what was your chosen sampling method
statified = geographical knowledge to choose location (after each tributry)
why was your samplying method appropiate for your enquriy
it is feesable in the timelimit, we know where the river changes and we can locate change at those sites and easily collect data
give two risk assessments and how to avoid them
- slipping/tripping = sensible footwear, follow paths
- drowning = avoid deep fast flowing water, stick to footpaths
what samplying method could have you done instead of stratified
systematic # measurements taken every 1km = less bias and manageable
what was your qualitative method of assessment
we used a field sketch and annotated around the sketches to highlight chacteristics of each site (gradient, pepple size, land use)
what were the two quantitive methods of analysis
- cross section area
- velocity of water
explain how cross section area was used to assess river Holford
- we used a tape measure to measure the width from wetted edge to wetted edge
- we divided the width by 10
- we used a meter ruler to measure the depth at the same points, ensuring the thin side faced upstream to reduce splash and inaccuracy
- we then used these measurements to calculate the area by multiplying them together
explain how velocity measurement was used to assess river Holford
- we used a tape measure and divided the width by 3 so we could take 3 readings per site
- we used a flow metre, ensuring the impellor faced upstream
- we timed how long it took the impellor to reach the base and recorded the value
- we then calculated the avergae at each site
how did you ensure reliablility for these measurements taken
- width = pull the tape taught and water to water
- depth = thin end upwards and bottom touching the base of river
- speed = ensure impellor was not touching base and it was facing upstream
explain why the pattern of your results for cross profile may not be completely accurate
we only took 5 measurements along the width and it would be more accurate if we took more as we may of missed a particulary deep or shallow section
explain the advantage of collated the class data
- anomolies wouldnt stand out as much
- more results recorded on a whole so more reliable
explain the overall pattern shown by the discharge measurements you took
- the further the distance downstream the large the volume of discharge gets
- becasue the river gets wider and deeper due to erosion by abrasion
- this allows for a larger channel with more discharge
- and as more tributries join, more water does as well
what were you data representations on the river Holford assessment
- cross profiles (width and depth)
- scatter graph (discharge)
- GIS location proportional symbols
explain the advantages and disadvantages of using cross profiles as a data representation
- +easy to read and compare
- +allows a view of depth and width
- +geolocated
- -you can miss points which are more shallow or deeper
explain the advantages and disadvantages of using a scatter graph to show discharge along the river Holford
- +shows anomolies well
- +allows for estimate of discharge in unassessed areas
- +read off it well
- -not geolocated = cannot tell where the measurements were taken
explain the advantages and disadvantages of using GIS location proportional syboms to show the discharge along the river Holford
- +geolocated = shows exactly where data is from
- +easy to read the proportional circles
- +can preform spacial analysis
- -cannot get exact values ~ you’re given a range
overall how was your presentation of data… effective or ineffective
effective becuase we could know where our data was from and allowing us to spacially analysis our results to reach our conclusion
describe youre results from the assessment
- as we travelled downstream velocity increased, discharge increase and cross sectional area increased. for instance the average wdith increased from 40cm to 2.1m from site 1 to site 5
outline your conclusion from your assessment down the river Holford
- as we travelled downstream, velocity, discharge and cross sectional area increased; supporting the Bradshaw model
- it was valid because our methods were reliable and we used technical equipment (flow meter)
- however human error did reduce accuracy as some anomolies were present although we did a line of best fit which supported our hypothesis nevertheless
comment on the strenght of your conclusion
it is semi-reliable as it fits in the bradshaw model, although the sampling rate is not high enough to fully be reliable
give two improvements included in your evaluation
- it would be better is we used a digital flow metre rather than an impellor to increase accuracy
- it would have been better if we used a laser metre rather than a tape measure to measure the width to increase reliablity
- we could have used a larger sample size by measuring more sites to increase reliability
