Strahler number

Strahler number is a way to measure the size of rivers, creeks, and streams. It gives us a way to compare the size of different rivers. To get a Strahler number, you trace a river backwards from its mouth (where it empties into a bigger river or the ocean) until you get to the source (where the river starts). As you're tracing it back, you look for branches (places where the river splits in two, like a fork) and count how many branches there are. Those branches each have a Strahler number (1 for the first one, 2 for the second, etc.), and when you get to the source of the river, you add up the Strahler numbers of all the branches to get the rivers's Strahler number. The bigger the Strahler number, the bigger the river!