Turbulence and Glenridding Hydro

I've been interested in doing some calculations of the flow rates through the system to try to estimate the input energy into the generators. I was able to estimate the efficiency of the Loch Ness scheme but I've been thinking about this in a different way. I estimate a 120m fall. Loss of gravitational potential energy means gain in kinetic energy means 1/2 mv^2=mgh so vsquared = 2gh and v=49 metres per second. That's over 100mph. Clearly not true. There are serious frictional losses in the system. There is some excellent information about flow rates in pipes on this website http://www.johnhearfield.com/Water/Water_in_pipes.htm but he points out that the lovely equation only works for laminar flow. If the water is turbulent, it doesn't work. We assess whether or not it is turbulent by using Reynold's number. Re=speed x diameter /hydraulic viscosity. I'd estimate the diameter at 0.3m. Hydraulic density is about 0.0013 at that water temperature. So Re = 11000 (2sf). Turbulence starts above 2000. Now I'm stuck.