Use Minimum Release from Reservoir Option
If this option is enabled the minimum release (as specified under the Operation tab in the Reservoir properties dialogue) is assumed to be routed through the hydropower station/plant and to be contributing to the total flow necessary for generating the required hydropower.
Note that this option must only be used when releases from the Hydropower plant and releases from the Reservoir are routed to the same river.
Example
If the hydropower demand requires a discharge of 100 m3/s through the turbines and the downstream release has been specified as 10 m3/s. Enabling this option will give a total release of 100 m3/s. If it is disabled the total release will be 110 m3/s provided there are no restrictions in water delivery for hydropower.