River Study
Fieldwork
Planning
• Why – Whitewater River
– Close proximity to the school/Killowen Outdoor centre
– Studying rivers/fluvial environments in Module 1.
– The river could be easily accessed and the sites
could be reached from the road (accessibility).
– Data could be safely collected at this river (safety
aspect). A risk assessment had been completed by
the teachers prior to the fieldtrip to determine that this
was the case. Nice clear water so we could see
where we were walking
– Discussed in class what to measurements would be
taken and how eg Width, depth, wetted perimeter etc
– Students were informed how to use the equipment
required for the above measurements and record
results.
Health & Safety Issues
• Obtain permission from Parent(s)/Guardian(s) – letters
home
• Collect medical information – eg asthma – take inhalers
• Take into consideration the size of the group
• Behaviour of students – fully co-operate with leaders and
teachers
• Consult a weather forecast
• Check each site for access and safety
• Carry a first aid kit
• Wear warm and waterproof clothing/protective clothing
(helmets)
• Inform others of your destination and time of return
• Bring a mobile phone
Health & Safety in the field
• Wear helmets. Buoyancy aids must be worn with
waders. Carry a throw line.
• Be aware of slippery and uneven surfaces –
rocks/boulders.
• Use the equipment properly. Take care with hazardous
equipment eg ranging poles.
• Potential hazards include Weils disease and giant
hogweed vegetation.
• Strong currents.
• Variable depths of water.
• Overhanging banks.
• In the event of an accident, remove everyone from
danger, apply first aid, phone for assistance and stay
together.
Overcoming Hazards
Hazard
Deep Water / risk of drowning
How to overcome it
Wear buoyancy aids, thrown a rope
line
Uneven surfaces / slippery rocks, body Wear a helmet in case someone slips
injuries
Cold, hypothermia, death
Wear a few layers rather than just one
thick one
Weather conditions
Watch the weather forecast & plan
accordingly
Water quality – weirs disease
Wash hands thoroughly, cover open
cuts, bring a first aid kit and antiseptic
wipes
Primary and Secondary Data
• PRIMARY DATA – that collected in the
field, river width, depth, gradient, GPS coordinates etc
• SECONDARY DATA
• Ordnance Survey maps – for altitude,
distance from source (see table)
• Weather forecast – bbc.co.uk
Sampling Methods
• What is the aim of sampling? It is
impossible to due to time and resource
constraints to test everything therefore
sampling becomes necessary.
• Systematic sampling was used for sites.
• Random sampling was used for bedload.
• Stratified sampling is used for an area
which has two distinctive areas e.g a rocky
and sandy area on a beach.
What did you do?
•To investigate how a river can change downstream, it
is possible to examine a local river
•Any river may be divided off into 3 main sections
called courses – upper, middle, lower.
•Various fluvial characteristics are measured at regular
points (10 Sites) along the White Water river
•This type of sampling is called systematic sampling
and it allows the investigation of continuous changes
as distance increases from the source of the river
•How are these things measured?
Aim of Fieldwork
• To investigate several physical characteristics of
the White Water River and how they change
from source to outflow
• The 6 characteristics we have chosen are:
• 1. Velocity (metres/second)
• 2. Width (metres)
• 3. Depth (cm)
• 4. Wetted Perimeter (metres)
• 5. Bedload size (cm)
• 6. Gradient (degrees)
Hypotheses to be Tested
• The river and its channel get wider as you travel
downstream.
• The depth of the river increases as you travel downstream.
• The velocity of the river increases as you travel
downstream.
• The size of the bedload decreases and its roundness
increases as you travel downstream.
Width
• This is measured by
placing one end of a
measuring tape at
one side of the river
channel, then pulling
it out to the other side
of the channel
• The distance is the
width of the river
Depth
• This is completed
using a metre stick
• It is lowered into the
water every 10 cm,
and the distance from
the top of the water to
the river bed gives the
depth of water
• An average of all
these readings is
taken
Discharge
• This is the amount of water passing any point in a
river in a certain river, normally given as cubic
metres of water per second (cumecs)
• It is calculated by multiplying the cross-sectional
area of a river channel at a certain point by the
speed (velocity) of the river at the same point
• The cross-sectional area is obtained by multiplying
the width of the river by the average depth
• The speed (velocity) of the river is recorded using a
flow meter (a small propeller attached to a rod) that
when dipped into the river gives a digital reading of
the speed of flow in metres per second
• Can also be recorded manually using flotation
objects such as twigs placed in the centre of the
river. These can be used to estimate the surface
velocity by timing the twig travelling a distance of
10m
Load
• The load of a river is the material it is carrying,
ranging from small sediment to large boulders
• It is very hard to measure the size of the load in
suspension, so instead, we can concentrate on the
load lying on the channel bed – called the bed load
• This load is measured for size and roundness
• By measuring the longest axis of 15-20 random
samples at each point an idea of the size of the load
is obtained
• Each stone is then given a rating for roundness
Wetted Perimeter
• This is the surface of the bed and banks,
which is in contact with the water in the
channel – measured by a tape, weighed
down with small stones across the river or
with a chain
Gradient
• The angle at which
the river is flowing
• This can be found
using a clinometer,
whereby 2 ranging
poles are set 10m
apart, parallel to the
bank and the inclined
clinometer indicates
the angle one is from
the other
Improvements to fieldwork
• Visit more sites – more than 10 sites.
• Take more readings to improve the accuracy of the data
collected. The bigger the range in your sample, the more
samples you should take to reduce errors e.g river
depth.
• Use digital equipment for data collection.
• Same students collect the same information at each site
to ensure consistency in the results.
• Allocate more time with the data collection – not rushing
– making errors.
• Compare results – different time of year / different river
• Compare results with other schools.
• More practice in using equipment to improve accuracy.
• Measure velocity always along the same transect as
where you measured width to ensure accurate cross
sectional area and so discharge