physical fieldwork

what is primary data?

data collected out in the field first-hand which helps us answer the enquiry question

what is secondary data?

data that has been collected by someone else like environment agency maps

what is qualitative data?

data that is subjective like field sketches which gives more understanding on people’s opinions

what is quantitative data?

data that is numerical and objective like the velocity of a river so it is more easy to compare

what is random sampling?

sites or samples picked at random

what are the advantages of random sampling?

can be used with large sample sizes, avoids bias

what are the disadvantages of random sampling?

can lead to poor representation / miss important bits not hit by the random selection

what is stratified sampling?

sites or samples selected for a reason to ensure appropriate coverage for the enquiry

what are the advantages of stratified sampling?

flexible and applicable, comparisons easily made

what are the disadvantages of stratified sampling (people) ?

hard to stratify data such as questionnaire responses

what is systematic sampling?

sites or samples selected at set intervals in the study area to ensure total coverage of the site

what are the advantages of systematic sampling?

straight forwards, good coverage of area

what are the disadvantages of systematic sampling|?

more biased, can lead to over/under representation

what is accuracy?

how precise it is

what is sample size?

how much is collected

what is control group?

the area studied

what is reliability?

how true it is

what is the bradshaw model?

describes how a river’s characteristics vary between the upper course and lower course
discharge, channel width, channel depth and load quantity increase downstream

what is the powers angularity scale?

it measures how angular/rounded sediment is
class 1 is very angular whereas class 6 is well rounded

what type of sampling is channel width and depth?

the sites were chosen through stratified sampling, the depth was systematic sampling

what was the equipment used to measure channel width and depth?

ranging poles, metre stick, 10 metre tape measure, recording sheet

how was channel width and depth measured?

channel width: two ranging poles put against the bank on either side, directly across from each other. 10 metre measuring tape pulled from one pole to another

channel depth: keep set up of channel width, use a metre stick to measure the depth of water at every half metre

what is a limitation of the method used to measure channel width and depth?

the metre stick may not have been placed exactly straight on the river bed, affecting the results for channel depth

what is a strength of the method used to measure channel width and depth?

systematic sampling was used so a good coverage of the control group was achieved

what type of sampling is river velocity?

stratified

what was the equipment used to measure river velocity?

ranging poles, three ping pong balls, timer, 10m tape measure, recording sheet

how was river velocity measured?

10m between one ranging pole and the other in the river, ping pong ball dropped at one pole and timer starts
once ping pong ball has reached the other pole, timer stops and time recorded for how long it took for the ball to travel - repeated three times
speed = distance / time

what is a limitation of the method used to measure river velocity?

ping pong ball could hit obstacles in river

what is a strength of the method used to measure river velocity?

repeated three times, improving the accuracy and reliability of results

what type of sampling is river sediment?

random

what was the equipment used to measure river sediment?

hands, metre stick, recording sheet

how was river sediment measured?

randomly grabbing a handful of rocks from the waterbed (15)

what is a limitation of the method used to measure river sediment?

person can be subconsciously biased and choose the rocks they like
may also be a poor representation of all the river sediment, as only picked up from one place at the site

what is a strength of the method used to measure river sediment?

very time efficient

what type of sampling are photos/sketches

stratified

what was the equipment used for the photos/sketches?

pencil, recording sheet

what representation method is used for the channel width and depth?

cross-section - x axis was width every 5 metres, y axis was depth every 5cm, plotted points joined with a line, coloured water level in blue

what representation method is used for sediment sample?

scatter graph - x axis was size in cm, y axis was angularity, plotted data of sediment in three different colours according to site collected at

what representation method is used for river velocity?

line graph - x axis was number of attempts, y axis was velocity in cm/s, plotted velocity in three different colours according to site collected at + joined points with line

what are four risks in the field?

slipping, drowning, traffic, getting lost, getting cold

what can be done to manage slipping?

wear wellies - appropriate footwear

what can be done to manage drowning?

use ranging poles to check the depth of the water
use stratified sampling to pre-determine safe sites

what can be done to manage traffic?

walk on footpath, only cross at safe points

what can be done to manage getting lost?

stay in groups of 5, supervised

what can be done to manage getting wet/cold?

wear appropriate clothing like coats and change of sockd

why is secondary data useful?

can show changing channel characteristics and flooding risk

what are three examples of secondary data?

OS maps, digimaps, environment agency website

what does the environment agency website show?

current flood warnings or alerts, river, sea, groundwater and rainfall levels, flood risk in the next 5 days, advice on how to prepare for a flooding event, text alerts sent to phone

what do OS maps show?

surroundings of river like the altitude, vegetation and housing
can be used to choose fieldwork site

what were the results for all three sites for river width and depth?

site 1 - width 3.32m depth 0.84
site 2 - width 3.25m depth 0.99m
site 3 - width 2.1m depth 0.83m

what were the results for all three sites for river velocity?

site 1 - 0.4m/s
site 2 - 0.25m/s
site 3 - 0.4m/s

what was the enquiry question?

how and why do the channel characteristics of the bexley river shuttle change and how do they influence flood risk?