Calculation of Shear Stress and Velocity Profile

Hello Tim,
I was searching the net because I am working on a project to measure the shear stress of water in a rectangular flume. I came across your post. First of all can you please tell me how did you calculate your shear stress? I know it was about three years ago but you might still remember! I am working on a project to measure the shear stress in different points of a channel and then graph it. I also want to obtain a velocity profile.
If you could give me the equations you used I will appreciate it. I found some equations but they are 2nd degree differential equations I have no idea how to solve them.

Thank you for your help.
If you have your script if you don't mind emailing it to me that would be also fine I can modify it to serve my purpose.

Thanks again!
John