Channel Migration mapping

[LambertNgenzi1]

I want to create polygons from NAIP or drone images of a stream over a period of time such as shown below. I am trying to find an efficient way to trace the stream channel in an automated way rather than tracing the stream channel manually (Which becomes very tedious for a bigger area). I tried without success this Image classification tutorial, https://youtu.be/6rWKle3DrD and I will appreciate it if anyone can help. 

Thank you in advance. 

  

[SusanaCrespo2]

Hi, I don't know if you got an answer to this, but I'm interested in this too.  I think an important step is to extract the centerlines from the different years.