Paper 3 - fieldwork unfinished

Why sample? 4 reasons

Not enough equipment/time; different parts => representative; avoids bias in choice of sites; quick/easy/convenient

Why is sampling useful for different geologies along coastline

Comparisons can be made between sites

Population definition

All the data from which you select sample

Homogenous population definition

Individual data within population very similar

Heterogenous population definition

Sets of data with varied population

What should you consider to collect a representative sample

How many samples needed; how to choose sample; how far apart samples are (distance + time)

Systematic sampling definition

Using a regular system to choose a data sample

Random sampling definition

Using a random method to select a data sample

Stratified sampling definition

Choosing data set that is in proportion of segments of whole population

Pragmatic sampling definition

Choosing dataset because of other reasons influencing the area

“Record land use every 100 metres”

Systematic

“Place quadrat according to coordinates from random number generator”

Random

“Estimate % of ecosystem covered by each type of dune and select frequency of sample sites matching this proportion”

Systematic

“Question anyone who’s willing to talk; place transect away from bushes”

Pragmatic

Advantages of stratified sampling

Quick/easy to identify intervals; choose intervals to cover whole area; equal intervals cover environmental gradient

Why can you save time and cover large areas of land with stratified

Quick / easy to identify intervals

Advantages of random sampling

Everything has equal chance of being sampled; avoids bias in selection

Advantages of stratified sampling

Representative of whole population; no significant group missed out

Advantages of pragmatic sampling

Practical

Disadvantages of systematic sampling

May be some bias e.g. if population has a repeating pattern; not all points have equal chance of selection

Disadvantage of random sampling

Might not be representative by chance e.g. random points don’t hit large areas

Disadvantages of stratified sampling

Proportions of subsets must be known + accurate; Need to use a different technique after to select sample from each segment

Disadvantage of pragmatic sampling

Most biased so not useful for further analysis

What does removing bias do

Provide reliable results

What technique would you use to investigate environmental gradients

Systematic

What does covering the whole area do

Improve accuracy

Main enquiry question for flows

How do coastal management strategies affect the natural sediment flow in Swanage Bay?

Subquestions for flows

Why does swanage need coastal management; what strategies are in place; how effective

3 kinds of primary data we collected for flows

Groyne drop to beach; Field sketch; Wave measurements (frequency + direction)

How did we do the groyne drop measurements

Measure top of groyne post to top of beach sediment on north and south side of each groyne w metre rule; repeat for all

Strength of groyne drop to beach

All 12 groynes => reliable; metre rule eye level => accuracy

Weakness of groyne drop to beach

Error of parallax = dec. accuracy; unable to collect from parts in sea = bias in where we took measurements

Field sketch method

Made a field sketch from a high point overlooking the bay

How did the groyne drop measurements help enquiry

SQ3 (effectiveness): supposed to prevent longshore drift S→N, so sediment should be higher on S side (smaller groyne drop)

How does field sketch help enquiry

SQ2 (strategies in place)

Strength of field sketch

Detailed annotations = relevant features; easy to understand; Added compass directions so we knew which direction view is facing

Weaknesses of field sketch

Time consuming to add lots of detail; limited viewpoint, not whole area; no scale; depended on abilities => dec. accuracy

How did we do the wave measurements

Count number of waves in one minute and which direction they came from

How did wave measurements help enquiry

SQ1 (Why management needed): calculate destructive/constructive waves; which direction waves coming from

Strength of wave measurements

Lowkey helped answer SQ1 bc/ destructive waves

Weakness of wave measurements

Different subjective ideas of what wave is; only counted how many waves in one minute => dec. reliability; anomalous wind direction to normal prevailing => unsuitable to draw conclusions

What secondary data did we collect for flows

Photos of the beach; map of sediment transport; geological map

What is secondary data

Data collected by someone other than yourself