There is a hypothesis that the average sinuosity of the world's rivers should be equal to π (3.141593). Numberphile produced a video discussing the idea and stated that there didn't seem to be any recorded data to actually check to see if it is true. This project aims to solve that.
Sinuosity is the ratio of the river's length to the straight-line distance between its source and mouth. For example, the Amazon is 6992.0km long and has a direct straight-line distance of 3026.7km, giving it a sinuosity of 6992.0 / 3026.7 = 2.31, notably less than π.
This data has been crowd sourced and so is potentially guesswork and estimations. It is often difficult to find the exact source of a river, and indeed many rivers have multiple sources that are debated. Furthermore some named rivers are tributaries to larger rivers and different lengths are given depending on how you look at the data.
With 280 rivers the average sinuosity is 1.916233, with a standard deviation of 0.730769.
This is a difference of 1.22536 from π, or an error of 39.004415%.
The code for this project is available at github. If you are interested in getting involved, either just submit your local river to the right or contribute and discuss via github.
I intend to continue updating the site with some interface improvements and potentially importing a massive set of data on rivers to improve the accuracy of the results.
pimeariver.com is undergoing a major rebuild which will involve importing the river data for the entire globe from Open Street Map.
In the meantime adding your own rivers has been disabled to prevent the data from being spammed. Sorry for any inconvenience, you can follow the updates progress on github.