A 20-foot concrete Parshall flume installed in Bijou Canal near Greeley, CO.  At the entrance of the flume radius wing walls smoothly direct flow into the converging section.

In his initial publications, Dr. Parshall had flat 45 degree wing walls at the entrance of the flume.  Radius wing walls appear in later publications by Dr. Parshall (1950, 1953).  Radius wing walls can help to correct the wave / trough phenomena reported by Blaisdell (1994).