river alyn Flashcards
Hypothesis and aims
Hypothesis -To investigate How does the River Alyn change as it goes downstream
Aims - To see how the river Alyn changes as you go downstream -width, depth, velocity and bedload
Reason location is suitable for physical enquiry:
River length is achievable in 1 day.
Road access to river Alyn & car parks & footpath along river.
River safe to access throughout.
Alyn waters and loggerheads give permission to survey.
Within 2hrs drive of the school
Method 1: Channel Width
Sampling method: Systematic sampling – key sites chosen
Sample size: 4 sites upper to lower course..
Description: Place a tape measure from one bank to the other perpendicular across the water and hold it taut. Measure the width in Cm and record. Try to choose an average section of the river.
Method 1: Channel Width strength
-The method of data collection is simple to carry out.
-Systematic sampling is simple and has
good coverage of the study area.
weaknesses channel width
There may be some user error when
taking readings in Cm and not mm.
Tape measure needs to be taut and at a representative section of the river.
Method 2: Channel Depth
Sampling method: Systematic sampling – key sites chosen
Sample size: 4 sites – upper to lower course
Description: At 10cm points across the river, place a metre rule into the water and record the depth in Cm.
channel depth strength
Strengths
Allows you to see changes in depth
across the width of the river so can
calculate and draw cross sections.
Easy to record at same time as width.
channel depth weakness
Weaknesses
- Large rocks moved into the river by public
can distort results. - Difficult to get accurate readings off a metre
rule
Method 3: Velocity
Sampling method: Systematic sampling – Key sites chosen
Sample size: 3 sites – 1 out of flood risk, 1 near and 1 in flood risk area.
Description: At 3 points across the river’s width, place the hydro-prop into the water and calculate the time it takes for the impellor to reach the end of the rod.
velocity strength
Strengths
- Allows you to work out the velocity by
calculating 0.0277 + (3.2805/mean time), and then the discharge by calculating CSA x Velocity.
weakness velocity
Weaknesses
- Difficult to accurately record time impellor takes to fully turn as difficult to see in the water.
Water can be too shallow to use hydro-prop.
Presentation method:
Cross sections -
Histograms – pebble frequencies
Dispersions diagrams pebble roundness with mean, median, range and interquartile range.
Scatter graphs - Does the River Alyn fit Bradshaw’s model?
risk assessment
Slips, trips & Falls Risk of slips, trips etc walking along uneven paths & when entering river. Pupils told to walk along footpaths
where possible and take extra care when entering river.
Water borne diseases - Light risk of contamination of water borne diseases whilst measuring in the river. Pupils advised to wear gloves if they have open wounds or to wash hands with anti-septic gel before eating/drinking.
Wet weather is dangerous due slippery
surfaces. Hot weather also poses the risk of dehydration. - Students advised to bring plenty of water and sun cream if the weather forecast is hot. If the weather forecast is wet, students are advised to bring appropriate clothing and footwear.
strength of presentation methord
Strengths
The presentation methods chosen were the best to represent our collected data to try and prove or disprove the original hypothesis, as
they showed changes over the course of the river and allowed for data manipulation including spearman’s rank.
weakness presentation
Weaknesses
Data presentation methods used made it
difficult to compare and identify patterns
alternative presentations
Scatter graphs to show relationship between distance downstream and velocity with lines of best fit.
Bedload samples we could have placed pie charts on a map of the river to show how the data changes as you move down stream. This would have helped us to identify if there were
any patterns along the river.
methord carriued out
Aim: To investigate how channel characteristics change
downstream. Linked to the Bradshaw model
depth
Depth
Aim: To investigate how channel characteristics change
downstream. Linked to the Bradshaw model
velocity
- Velocity
Aim: To investigate how channel characteristics change
downstream. Linked to the Bradshaw model
results width
Data that could have been linked were bedload size and shape with location along the River Alyn. We should have seen the size and shape decrease as we travelled from the source to the mouth of the river
depth result
Overall our results showed that there had beensignificant alterations made to the river Alyn by man,
such as farming and mining. Therefore our results did
not match the Bradshaw model
velocity result
We could have also linked velocity (speed of the
river) with sediment size and shape and this would
identify if erosion was taking place.
conc
Overall there was clear evidence that human intervention on the River Alyn had an impact on the natural processes operating in the River.
The farming found near the source of the river widened the river, the rivers load did not change shape and size
as would be expected farming and mining have had a big impact on bedload and velocity in the river channel. Having a big impact on the Bradshaw Model and Long
Profile.
eval sample
Evaluation
Sample size
Only covered 4 sites along the river. More sites would
give more accurate measurements.
accurate velocity measurements using different method
eval frequency
Frequency of readings taken
Measurements taken during extended warm weather and less rainfall than normal. More valid conclusions could be made after surveying the river at different times of year.
