How A Contour Map Shows The Slope Of A Plot
From a field survey to working out how steep the land is
Making the map
Step 1
Survey the land
A land surveyor walks around the plot with a machine that captures coordinates and elevation.
Step 2
Record points at regular intervals
Readings are taken at points chosen at regular intervals across the plot.
Step 3
Upload to design software
The data is uploaded to design software such as AutoCAD.
Step 4
Join points of equal height
The software joins points at the same altitude, creating the contour lines of the area. Here, all the 102 m points form one line.
Reading the slope
Step 5
Draw a line for every 1 m
An interval of 1 m means the software draws a line for every 1 m difference in altitude.
Step 6
Measure the gap between lines
The distance between two lines is used to calculate the gradient. Here, the lines are 4 m apart.
Step 7
Divide interval by distance
The ratio of the 1 m interval to the 4 m distance gives a slope of 1:4, or 25%.
Step 8
Closer lines, steeper slope
The closer the lines are, the steeper the slope of that specific area.
