Offtake downstream conditions

In order to include the possibility of submerged flow conditions at the offtakes, three types of offtake downstream conditions (i.e., at the head of the secondary canal) can be modeled:

• a constant downstream water surface elevation

• a downstream water surface elevation Z2 that varies with the water surface elevation upstream of a free-flow weir:

Q(Z2) = µL (Z2-ZD)3/2 [25]

• a downstream water surface elevation that follows a rating curve of the type:

Q(Z2) = Qo( )n [26]

Figure 21