Theoretical Power: $P_{th} = \rho \cdot g \cdot Q \cdot H$

Mechanical Power (Turbine Shaft): $P_m = P_{th} \cdot \eta_t$

Electrical Power (Grid Output): $P_e = P_m \cdot \eta_g = \rho \cdot g \cdot Q \cdot H \cdot \eta_t \cdot \eta_g$

Where $\rho = 1000 \text{ kg/m}^3$ and $g = 9.81 \text{ m/s}^2$.