The problem of define flow ...
Published by Lior Asaf, PhD, International Business Development Manager at LDD Advanced Technologies Ltd.
The problem of define flow direction is very easy when you have a data on local topography
In many cases when there is a flat topography it's can be tricky
You can use the elevation profile from google earth to find the general elevation profile along your canal , the other option is to use the data from DEM. There is a good DEM from the Japan Aerospace Exploration Agency (JAXA)
https://www.eorc.jaxa.jp/ALOS/en/aw3d30/index.htm
please note that both data set are based on 30m grids **
Good luck
Lior .