5.9.4. Semi-Modular Outlets (Semi-Modules or Flexible Outlets) The simplest type of semi-modular outlet is a pipe outlet discharging freely into the atmosphere. The pipe outlet, described as the non-modular outlet, works as semi-module when it discharges freely into the watercourse. The exit end of the pipe is placed higher than the water level in the watercourse. In this case, the working head H is the difference between the water level in the distributary and the centre of the pipe outlet. The efficiency of the pipe outlet is high and its sediment conduction is also good. The discharge through the pipe outlet cannot be increased by the cultivator by digging the watercourse and thus lowering the water level of the watercourse. Usually, a pipe outlet is set so that it behaves as subproportional outlet, i.e., its setting is kept less than 0.3. Other types of flexible outlets include Kennedy’s gauge outlet, open flume outlet, and orifice semi-modules.
