Open Channel Hydraulics

							Open Channel Hydraulics

In this section we will apply the principles of fluid mechanics to surface-water flow in
channels. The concepts develop will form the basis for describing flow in streams and
rivers.


Basic Relationships



         Equation of continuity                Q1  Q2


                                               U2   p
         Bernoulli equation,                          zH
                                               2 g g


                                                        L U2
         Friction factor relationships,        hL  f
                                                        D 2g
                         Starting Point
    Frictionless flow with horizontal channel bottom

   specific energy
   specific energy diagram
   flow criticality
        o subcritical             F<1
        o critical                F=1
        o supercritical           F>1
   use in calculating discharge with control structures




      Frictional losses with sloping channel bottom


   Manning’s equation
        o used to estimate Q without measuring velocity
            directly
   vertical velocity distribution in channels with friction




           Measuring flow in natural channels

   velocity-area method
        o mean velocity method
        o mid-section method
   surface velocity method