Measurements Flashcards
Clinometer (measure slope angle/gradient)
With ranging poles
- 1 pole at top, 1 pole at bottom
- Look through + measure angle from 1 pole to another
- Take up and down reading (accurate)
Pebbleometer (measure size + shape of beach/river material)
Basic, quick, accurate
Plastic box with measurements on inside + v shaped faces
Calliper (measure width, depth + length of load)
Small objects/load
Record changes in river load/beach material
- Place object inside + close it
- Read measurement (cm/mm)
Infiltrometer (measure infiltration rates)
Infiltration rates of different surfaces
- Place on surface (make sure seal is secure)
- Fill with water
- Time how long water takes to infiltrate
Flowmeter (measure river velocity)
- Measure width, divide by 4
- Place small propeller under water surface at each 0.4
- Turns in water to give velocity m/s
- Small digital readout gives speed
- Different points across river - compare with cross sections
ADV: simple, accurate
DIS: might get stuck/on floor, water too shallow
Roundness index (measure shape of object)
Look at changes in river load from source to mouth or across meander
Scale:
Very angular, Angular, Sub angular, Sub rounded, Rounded, Very rounded
- Reach into river, index finger directly down
- Pick up first pebble touched
- Measure length + score roundness
- Repeat at several points across width
Float (measures river velocity)
Use floating object (table tennis ball)
- Measure distance with tape measure + 2metre rules (10m)
- Time how long it takes object to travel 10m
- S=d/t to calculate velocity
- Repeat for average + avoid errors
ADV: cheap, easy
DIS: not accurate, slowed by wind, could get stuck on rocks
Measure width + depth of river
- Place 2 ranging poles either side at banks
- Width reading from end of measuring tape
- Divide width by 10
- At intervals place metre rule downwards
- Cross sectional area = av depth x width
Stand downstream to not obstruct water flow
Destructive/constructive waves
Destructive: stronger backswash, remove material, steep/narrow beach
Constructive: stronger swash, deposit material, gently shelving beach
Measure wave frequency to identify
Measure beach profile
Compare transects on beach/different beaches
- Ranging poles from top to low water mark
- Walk between 2 poles, make general note (steep spots)
- Where slope changes, use poles/clinometer to measure gradient
- Ground distance between measurements
- Construct cross sectional profile
- Repeat
Measure beach material
- Choose sampling type and number of points
- Quadrat chooses pebbles/particles
- Measure pebbles or sediment using roundness index chart and ruler
Take account of recent or long term, effects
Quadrat (measure vegetation cover)
50cm2 divided into 100 squares
Calculate % area covered or different types
Randomly selecting river load/beach material:
- Place over area
- Random numbers table selects square to collect from
Measuring longshore drift
Analyse swash backswash and how material is transported along beach
Plot dist 10cm along section of beach and mark start and end points
Place float in water at point where waves breaking
Watch flair and time taken to travel the 10cm along beach
Measure different sample points along beach shows most active and least points
