# Geographical Skills Investigation River Answer Flash Cards

- Created by: isobel.hart
- Created on: 19-05-16 13:43

First 1042 words of the document:

The aim of my inv estigation was to ev aluate the relativ e influence of the v ariables identified by the Bradshaw M odel

on the pattern of discharge along a section of upland riv er. I used Spearman's Rank Correlation Coefficient (rs) to

determine the strength of the relationship between discharge and distance downstream. The Spearman correlation

coefficient, rs, can take v alues from +1 to -1. A rs of +1 indicates a perfect association of ranks, a rs of zero indicates no

association between ranks and a rs of -1 indicates a perfect negativ e association of ranks. The closer rs is to zero, the

weaker the association between the ranks. This allowed me to either accept or reject my null hy pothesis.

Data analysis/ how appropriate was it to First I tabulated the data, ranking them giv ing the highest the v alue '1'. Identical v alues were giv en equal ranks. Next I

found the difference (d) between the ranks and squared them (d2). I then did the sum of d2 and used the formula to get

the data? the coefficient. I interpreted the data, +1 being a perfect positiv e and -1 being negativ e. I compared this to a significance

table to determine the strength of the correlation. This rev ealed that there was only a 0.01% probability that a strong

0.93 probability was down to chance. This didn't prov e a causal relationship but does form the basis for further inquiries

to establish the reasons, assessing the contribution of the key v ariables.

The positiv es of using Spearman's Rank Correlation Coefficient are that it shows the significance, can prov e or disprov e

the correlation between discharge and distance, allows for further analy sis and it doesn't assume a normal distribution.

It is a statistical measurement, so is a non-bias measurement of the relationship between two v ariables, to test the

significance of the correlation. For example, the result for wetted perimeter was 0.855 and was significant when

compared to a critical v alues table, and we found that this had a 99% confidence lev el that the relationship didn't occur

by chance, making it v alid.

The negativ es include: that it is a difficult and complex equation, it can be misinterpreted and it needs two sets of

v ariable data.

A risk assessment was conducted both prior to and continuously throughout the process of

primary data collection. A score of the likelihood of the event, was given to each hazard, this

was multiplied by the potential outcome. If it exceeded the acceptable level then it would

either have to be reduced or the trip would have to have been cancelled. Whilst travelling to

and from sites in the minibus, wearing seatbelts was compulsory, providing protection in the

Describe and justify measures taken to case of collision. Food allergies were identified and catered for. Appropriate footwear was

worn (e.g. wellies and walking boots) to prevent hypothermia and to reduce the chance of

reduce risks.

slipping. Waders were also worn as a hypothermia prevention method. When entering the

river, a stable, low bank with easy access was chosen, to reduce the chances of slipping or

falling over. Also there was no independent entering of the river, everyone entered in groups of

3 or more, in order to support each other and prevent accidents from occurring. We stayed

together at all times, having designated partners. We only entered at suitably shallow riffles,

where it reached no higher than knee level, and the water was moving at a relatively low

velocity. This was done in order to ensure that no one was overpowered by the river and thus

prevented the risk of drowning. Sites 6 and 5 were considered too deep when conducting our

continuous risk assessment, so we responded by moving further downstream.

Our chosen location was the river Glaven, North Norfolk. The area

sampled was just outside Holt and Hunworth and finished at

Glanford. The river is chalk bedded, and runs through a mixture

Describe the characteristics and location of deciduous and evergreen trees. The river continues into

of your field work marshes at Blakeney Point. The surrounding farmland is mixed

arable. We sampled 10 sites along its 17km stretch. The gradient

was very flat all along the river as the surrounding area had been

drained. Site 1 was 40m above sea level and site 10 was less than

10m, making it an unusual river.

I was able to identify that the Bradshaw Model is not applicable to all rivers.

For example, I found a negative correlation between discharge and distance

downstream, Spearman's Rank Correlation Coefficient turning up a value of

Explain how your enquiry improved your -0.697. This is the exact opposite of what the model suggests. In turn I had

to accept my null hypothesis. More research would be required as it is

understanding of the topic likely that there are errors in the investigation and other rivers might turn

up differing results, proving the Bradshaw model. The investigation allowed

me to extend my understanding of the limitations of the methods used to

investigate a river, which is hard to truly comprehend and visualise without

hands on experience.

The Bradshaw Model is a theoretical model which describes the

changes (in terms of the characteristics and behaviour) we would

expect to see as a river travels from its source regions in its upper

course with increasing distance downstream towards its mouth. It

Explain the geographical theory behind graphically represents how a number of variables change

your fieldwork enquiry downstream. The aim of my geographical investigation was to

assess the validity of this model. Specifically, testing factors

influencing discharge (cumecs) - wetted perimeter, cross-sectional

area and velocity. The Bradshaw model suggests that as the

discharge increases, so does velocity, wetted perimeter and cross-

sectional area, as a result of the channels increasing smoothness.

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