familiar fieldwork - river Tillingbourne Flashcards
why processes are affected by the energy of a river and how can we measure this
erosion, transportation and deposition
measure the velocity and discharge
three changes expected to observe throughout the river and why do we see these changes
- upper course -> narrow channels, large bed load and landforms like V-shaped valleys
- middle course -> channels widen and deepen, landforms like meanders
- lower course -> wider and deeper channel, landforms like floodplains and levees
see these changes because discharge increases and particle size decreases -> traction makes them smaller
location of river Tillingbourne
flows between dorking and guilford in surrey
size of the river Tillingbourne
length - 19km
drainage basin - 59km^2
is the river small or large scale
small scale
how might the size of the river impact the discharge
discharge is fairly small -> smaller river -> less risks
how much of the drainage basin in high or low permeability
high - 90.39%
low - 0.95%
how much of the drainage basin is covered by woodland and how does this impact the river
49.69%
protects river from too much discharge
-> roots suck up water
-> water interception
how much of the drainage basin is covered by grassland and how does this impact the river
23.2%
keeps discharge low
-> absorbs water
how much of the drainage basin is covered by urban areas and how does this impact the river
9.9%
impermeable surface
-> causes flooding
which sampling strategy could we use and why
systematic so we can measure the river in even intervals
title of investigation
to investigate how the river Tillingbourne changes downstream
data presentation
- cross section (width and depth)
- bar graph (velocity)
- annotated photo
- scatter graph (mean width/distance from source)
primary data
velocity, width and depth, field sketch
secondary data
landuse survey, OS map, FSC data, environment agency
sampling
systematic + stratified
stratified site to sample characteristics then systematic across the river channel - 5 sample points per transect
location choice
tributary of the river Wey. source Leith hill
close to school
-> easy to return to for repeat measurements
risks
drowning
weather
slipping
Weils disease
theory
Bradshaw model and the changes in river characteristics from source to mouth
hypothesis
river velocity will increase downstream. channel width and depth will increase downstream
velocity:
- measure out 5m of the channel lengthways
- dropped the cork just ahead of the person holding the tape and timed how long it took for it to move from one person to the other (5m)
- velocity = distance/time
- quantitative data
- stratified sampling
- variable reliability as cork could get stuck in current
measuring width and depth:
- measure width of river at sample and recorded it
- divide width by four so we can sample sites at equal distance across river channel
- quantitative data
- stratified and systematic
- reliable but some innacuracy
fieldsketch
- drew a fieldsketch at crossways farm to show nature of river and its size
- helps to identify why there might be anomalies in the data
- qualitative
- stratified as we picked the location
- subjective as it’s down to individual interpretation
- reliability varies depending on detail and if scale was used
final conclusion
- channel depth and velocity increase as you move downstream
- width has an anomaly at site 2 due to human influence
