Flashcards
Cranedale
Flashcards do conjunto (32)
- 1Outline the aim of the investigation?To investigate downstream variations in river channels and make links between changing velocity, channel size, bedload size and wetted perimeter
- 2Describe the theory, idea/ concept underpinning the investigationTo discover if the Bradshaw model can be applied to the River Derwent, theory suggests that rivers change in characteristics due to changes in discharge, gradient, velocity and erosion
- 3What hypothesis were tested?Velocity increases from the source, hydraulic radius increases from the source, channel depth and width increases from source and bedload becomes more rounded
- 4How did you respond to risks at your sites?A full risk assessment was conducted at the river edge before any data was collected, a hazard was identified given a L, M or H risk and a control measure was put in place
- 5What were the associated hazards?Slipping on mud - M - watch where standing, walk on path.
Drowning - L - check water levels, work in riffles not pools
Diseases eg. weil disease - L - Don't drink water, wash hands, cover cuts - 6Describe the catchment area
- 7Why was this area suitable?Rapid changes found more in the upper course of rivers - only had 4 hours to do tasks, shallow and free from dangerous currents, land owners permission, little influence from humans which could change channel characteristics and produce misleading results
- 8Describe and justify how you investigated a river transect?Tape measure to measure present flow, divided by 10 to get interval distance, systematic sampling cuts out bias, depth of river measured at each point by ruler, held with narrow edge facing upstream, bedload was picked up based on where the ruler was placed, given a grade on the powers of roundness scale
- 9How did you determine the wetted perimeter?Chain placed in water where it touched the bank at one side to the other, carefully fed across the bed and then removed and measured using a tape - chain was held at the top and hands ran down to get an accurate measurement
- 10Strengths of investigating a river transectSystematic sampling cuts out bias and provides consistent data, meter reading gives good precision that can be easily compared, came to decision as a group on bed load cuts out individual bias
- 11Strengths of wetted perimeterChain is heavy and sits on the bed and is not disturbed by river velocity, it produces an actual measurement that can be contrasted with other sites
- 12Weaknesses of river transectIs a sample size enough as the river gets wider downstream? Sampling can affect accuracy eg. if the ruler falls behind a stone or if river flow varies across a river, powers of roundness is qualitative technique, pictures aren't hugely accurate
- 13Weaknesses of wetted perimeterChain was too big to fit into all the nooks and crannies of the wetted perimeter. the chain was too short for site 3 and had to be picked up and moved - losing accuracy. chain can move at high velocity - at site 3 on thalweg, and too deep to see the chain
- 14How did you respond to the risks in doing this data collection?Various control measures were put in place when examining the site before conducting the data collection, this included: checking water levels, water depth, temperature.
- 15Describe one method of data presentationChannel cross sections
Horizontal scale of 1=50cm and vertical of 1cm=25cm, used same scale for each site to allow direct comparison, same piece of paper so could directly compare - 16What difficulties arose with this data presentationThe selection of an appropriate scale was difficult to do to be able to contrst them easily, what about sides between sample positions, a line is drawn - doesn't match true cross section, this technique showed us the cross sections, it did not interpret the results and give a meaningful degree of correlation
- 17What ICT application was used?QGIS - free, mean velocities were entered into a table and the resulting symbols were superimposed into a map of the area, the bigger the symbol, the higher the velocity
- 18Problems with GIS?Easy to input wrong data,
symbols can be too big and overlap each other causing confusion,
when additional info was plotted it became too confusing - 19Advantages with GIS?Free,
can visually see the changes on the same screen,
can make links between differing river variables, eg. velocity and bedload size - 20Other uses of GIS?Coastal erosional rates can be compared between dates and areas, plotting development of settlements such as Kilham and Seamer, asses areas of potential flood risk and plan accordingly, crime in areas, olympic torch route
- 21What other techniques were used to present data?An annotated field sketch/photograph could have been completed for each site, Advantages: you can add your own annotations that pick out the main themes under investigation, very visual
Limitations: need to be a good artist, sketches can be open to personal bias- qualitative data - 22How was your data interpreted?Spearmans Rank:
Analysis technique as it gives you a statistic that can be used to state the strength of a relationship between 2 data sets.
i got 0.96 - therefore with 95% confidence a positive relationship exists between velocity and hydraulic radius - 23Advantages to Spearmans rank?Provides a numerical value that summarises the degree of correlation between 2 variables, it is not open to personal interpretations - quantitate evidence, test can be done with any data sets containing raw figures
- 24Disadvantages to Spearmans rank?Only had time to visit 3 sites, this technique needs at least 10 to be reliable. We had to use secondary data which could be unreliable. If data is the same, too many tied ranks can interfere with validity of the result. It gives a level of confidence not certain
- 25What is meant by significance of result?This means to what extent are you confident that a relationship exists between pairs of data. If your answer lies below 95% confidence - it is rejected in Spearman's rank calculations
- 26What do we mean by anomalies?A piece of data that doesn't fit the general trend of the rest of the date site 3 - higher velocity than site 4- due to going through Broxa forest - more interception, can be positive/negative and enable you to make further investigation into other factors that could have influenced the 2 variables being tested for a relationship
- 27Issues of secondary data?Was the data collected in the same manner and time of year as we did it? has it been collected accurately. Secondary data can be useful to enhance understanding such as looking at OS maps at the sites we visited to see if wider links could be made
- 28How else could we have interpreted our findings?Scatter graph
Best fit lines give a good visual indicator of what type of relationship exists
Anomalies can be highlighted and can provide basis for further investigations, plotting a best fit line is difficult if wide spread of data, it doesn't give you what degree of relationship exists - 29Did your answers match the theory/ summarise your findings?Velocity did increase as it moved downstream, issue at site 3 - meander, site 6 channelisation, channel depth and width increased, hydraulic radius increased from the source
- 30How could this be improved?Only 3 sample sites, none in middle/lower course. Relying on secondary data is fraught with difficulties
Several visits needed throughout the year to get an average set of results eg. chains for wetted perimeter being smaller, making comparisons with other rivers - 31Could your fieldwork be of use to other people?Hydrologists: might be able to identify areas of potential flood risk/prepare appropriate defences,
Insurance companies: insurance prices for homes/businesses
Water companies: Identify times of year when water can be extracted for other uses eg. farming - 32How has the investigation improved your understanding of the topic area?No variable is dependent on the other. Differing processes are more dominant in certain parts of rivers which produce differing landforms. The channel characteristics and valley cross profile are linked. Humans can play an important role in determining channel characteristics. Natural factors can alter velocities eg. interception at site 4
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- A level Geography FlashCards sobre Cranedale, criado por Lucy Puddephatt em 08-05-2017.
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- Lucy Puddephatt
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