fieldwork - carding mill valley

Aim

Investigate the changing characteristics of the stream at Carding Mill Valley as it travels downstream and whether physical processes along the river were affected by human activity

Why was location good?

Human

- only 1hr 20 drive

- land owned by national trust so allowed access and good footpath

- lots of parking for coaches

- facilities near by - toilet, cafe

Physical

- river wasn’t too deep or wide so didn’t get too wet

- can get a good range of upstream and downstream

Risk assessment

- getting lost

- accident in bus

- tripping hazard

- rock landfall

How obtain river velocity site

Systematic because approximately 5m between each group

How to obtain the bedload shape and length

Systematic with every 5 meters

Random location with the 5 meters to avoid bias

How to obtain channel depth

Systematic because measure the river depth at 10 equal sites across the width to give even coverage

Overall how were sites decided

Stratified

- 2 upstream of human management and 2 downstream of human management

- to show how human management has affected the river

Method for measuring the velocity of the river

- measure 5 meters along the river using a tape measure

- use ranging poles to mark the start and the end

- drop the dog biscuit as start of 5 meters

- time how long it takes for the dog biscuit to travel the 5 meters

- repeat 5 times

- collect data at 4 sites

- work out average time and then speed = distance/time

Justifications for this method

- carried out 20 times to get an average to improve accuracy and highlight anomalies

- used dog biscuit because they float so could measure velocity of surface water and they are biodegradable so no litter to the environment

- repeated 5 times to get an average to avoid anomalies from human error

- 4 sites were manageable in the time allowed and reflect Bradshaw model of investigating velocity

Advantages of this method

- dog biscuits were biodegradable

- did it 5 times to find an average

- quick to carry out

- dog biscuits float so easier to see

Disadvantages of this method

- dog biscuits got stuck a few times which means that some measurements took longer

- reliant on reaction time

- dog biscuits got heavier throughout the measurements

Improvements

- drop 2 meters before so can gain momentum

- do the data on different day to compare weather

- use a flowmeter which will be more accurate

Method for bed load and shape

- measure 5 meters

- choose a random number from the random number sheet

- pick up rock from this measurement

- measure longest axis of rock and shape as described on the card

- repeat with 10 different measurements

- find the average of the data

Justification of this method

- used ransom number sheet to avoid bias

- measured the longest axis of every rock to get fair measurements

- repeated 10 times to highlight any anomalies and calculate a mean

Advantages of this method

- using 5 meters gave good coverage of the river

- random number avoid bias

- quick to get a lot of data

- little technology required

Disadvantages of this method

- not a rock in every location

- may not know pattern as only data from 4 sites

- subjective on what the rock look like

- time and place specific data

Improvements

- pick rock with eyes closed so less bias

- same person deciding shape of rock