physical fieldwork

enquiry question

how successful are the groynes on Swanage beach

S - simple

• POSITIVE

  • enquiry question has one command word (how)

  • enquiry question looks at one type of coastal management on one beach

M - measureable

• POSITIVE

  • enquiry question allows us to measure tangible primary data and cross reference with secondar data

• NEGATIVE

  • criteria for ‘successful’ is unknown

A - achievable

• POSITIVE

  • we have the equipment needed

  • we have access to the secondary data online

• NEGATIVE

  • beach can be really busy

R - realistic

• POSITIVE

  • area of study is near to our accomodation

T - time

• POSITIVE

  • collecting primary data from just 2/18 groynes

  • easily can be completed in a few hours

hypothesis 1

• there will be more sediment on the south of the groynes

• as they successfully prevent longshore drift

• and increase deposition

hypothesis 2

• the area of the beach with groynes

• will have more sediment

• and less erosion

• than the coastline that is unprotected

hypothesis 3

• the groynes on Swanage beach

• are a cost-effective coastal management strategy

justification for hypothesis 1

• south-westerly prevailing wind

• results in swash transporting sediment up the beach

• in the direction of the prevailing wind

• process results in longshore drift from south to north

• groynes will interrupt this process

• and sand will be deposited by the waves

• on the south side of the groyne

justification for hypothesis 2

• where the coastline is unprotected by groynes

• sand will be transported by longshore drift in a northerly direction

• meaning there is less sediment in front of the cliffs

• as sediment absorbs the waves energy and reduces the impact of hydraulic action and abrasion

• there will be more erosion on the unprotected coastline

justification for hypothesis 3

• groynes are one of the best and most commonly used hard engineering coastal management strategies

• cost ~£100,000 per groyne

• making them one of the cheapest defences

• with a life span of above 30 years

chosen sampling strategy for data collection

• pragmatic sampling

• as some of the groynes may be damaged

• and some groynes may have people near - it’s considerate to avoid these

data collection method - hypothesis 1

beach profile

data presentation method - hypothesis 1

cross section

describe how to measure a beach profile

1. place a ranging pole at the high tide mark 2m to the side of the groyne and another 2m up the beach

2. use a clinometer to measure the angle from the same point on the first ranging pole

3. move first ranging pole 2m up the beach from the second one and start again

data collection method - hypothesis 2

annotated field sketch

data collection method - hypothesis 3

secondary data analysis

state rate of erosion on Swanage beach if no defences were in place

0.4m/year

state number of properties lost if no defences were in place (50-100 years)

144

state value of properties lost if no defences were in place (50-100 years)

£36,122,000

what does secondary data show about the effectiveness of groynes in Swanage

• shows groynes are cost effective

• £2.2 million spent to protect

• vs. potential £7 million in losses

• over 20-30 years

describe the effectiveness of rock armour

• cost - £2000 per m

• life span - 25 years

• cost (50 years, Swanage) - £6 million

describe the effectiveness of sea walls

• cost - £6,000 per m

• life span - 100 years

• cost (50 years, Swanage) - £4.5 million

describe the effectiveness of gabions

• cost - £500 per m

• life span - 10 years

• cost (50 years, Swanage) - £3.75 million

describe the effectiveness of timber revetments

• cost -£2000 per m

• life span - 25 years

• cost (50 years, Swanage) - £6 million

data presentation method - hypothesis 3

bar graph

state whether we accept/reject hypothesis 1

accept

state whether we accept/reject hypothesis 2

accept

state whether we accept/reject hypothesis 3

accept

positive of beach profile method

• repeated clinometer reading to make it more accurate

• held tape measure taught for accuracy

• 2 different groynes so reliable sample

• pragmatic sampling

negative of beach profile method

• inaccurate analogue clinometer

• wind affecting tape measure

• hard to keep ranging poles in sand at exactly the same height

• cross sectional area calculation is an estimate and not exact

positive of annotated field sketch method

• able to focus sketch on hypothesis

• detailed annotations

• included title, directions, scale

negative of annotated field sketch method

• depends on sketching ability

• difficult to be objective

• only shows one view at one time

positive of secondary data analysis method

• used government sources for data so likely to be accurate

• very easy to access and quick to do

negative of secondary data analysis method

• BBC News article could be inaccurate as newspapers are often written with agenda

• data for coastal management is a UK average and very variable

positive of cross section presentation

• very visual

• shows profile clearly

• very easy to do online

• calculate cross sectional area for you

negative of cross section presentation

• have to estimate between data points

• can’t compare both profiles on one graph

positive of bar chart presentation

easy to construct and interpret

negative of bar chart presentation

• not geo-located

• can only use discrete data