# Geography - data presentation techniques

• Data presentation techniques -- The river Holford
• Line graph
• One technique is drawing a line graph with distance downstream on the x axis and velocity in m/s on y-axis
• Why  this is good
• This clearly shows how our readings changed downstream
• It is easy to read precisely
• You can easily see values
• There wer large gaps of over 1km between some sites so the line drawn may not reflect the actual velocity between sites
• It also does not clearly show the location of the sites and the river context -- a map is needed
• Proportional circle map
• I produced a proportional circle map with ArcGIS online where the velocity values were shown as circles of varying sizes
• The size becomes bigger depending on the velocity at each size
• A key was produced to help read the values for each circle
• Benefits
• It clearly shows the data
• It shows where the data was collected
• It shows the map, meaning you can see the factors influencing the results
• You can compare results to background layer eg/ geology
• Problems
• It is not clear what the exact values are
• You do not have any indication of the values between points
• Cross-sectional areas of the river channel
• Using our depth readings across the I drew a scaled diagram of the shape of the river channel
• 4cm on the page equaled 1m in real life
• I drew these to help me see the channel shape and how friction in it will influence velocity
• I could use it to calculate the cross-sectional area  and the hydraulic radius to see how they influenced e velocity
• However they will not be fully accurate as we only have 5 depth readings across the channel
• they are Also very time consuming to draw
• Scatter graphs
• This is to show how strong the correlation is between velocity and influencing factors like hydraulic radius
• I drew a scatter graph and drew a trend line to see the strength of the correlation
• I looked to see if the correlation was positive or negative
• I used this to see if the correlation was weak or no correlation
• Data analysis
• HR = CSA/WP
• percentage change = difference in site 1 to 5 value / original    x 100
• We had 6 groups at each point, each made 3 measurements= overall we had 18 which we got the mean from
• For the cross sectional area we used  the average depth and multiplied it by the average width to get the cross sectional area