GeoGraphs

My brother’s doing his International Baccalaureate Diploma right now and for one of his Geography assignments he had to make these graphs -cross sections of rivers- he called them geographs because… they’re for geography and because it has fewer words, so that’s what I’ll call them here. He drew them by hand but they got smudged and I thought it would be nice if he could make them digitally, but that’s a lot of work. I then thought it would be good if there was an easy way to do this, and, having found one, I’ve decided to share it with the world so that other IB students can benefit from this too!

What is a GeoGraph?

It’s a bunch of points on a graph that shows the depth at different points of a river the class studies.

A graph looks like this one:

Example GeoGraph
Example GeoGraph

And as I understand, it works like this:

  1. there is one graph for each transect measured at different points on the river
  2. the width of the transect is shown
  3. the width of the graph is scaled to the width of the transect
  4. the depth of the river is shown for different points along these transects
  5. the depth is measured at 5 points along the transect:
    1. at the start of the transect
    2. at the end of the transect
    3. halfway between the start and the end
    4. halfway between the midpoint and the start
    5. halfway between the midpoint and the end
  6. the depth is measured as a negative number
  7. because depth is negative the graph is drawn below the x-axis
  8. the graph is shown as an irregular polygon connecting all points on the graph
  9. there is a line along the bottom of the polygon connecting the first and last points
  10. this line is as low as the lowest point on the graph

That’s a lot of points to consider, and it’s why this graph is not easily done using the graphing functions of your spreadsheet application (for most of you that’s probably MS Excel). A lot of people might get frustrated, or resort to just drawing it in Paint or some other simple drawing program, which is much too much work! Don’t worry there’s a much easier way of doing it, and it’s all described below. Continue reading