Hydroelectric power plant $($hydroelectic power plant$)$ has a water flow rate from the top $($higher position$)$ to the bottom reservoir $($lower position$)$ equal to $120$ m $/$ s$,$ with a head, energy loss due to the flow in the pipe system $($fiction loss head. h$)$ equal to $30$ m and use a water turbine generator $($turbine generator$)$ to change water energy to electrical energy. If the top water level is higher than the water level below $100$ m and the efficiency of the water turbine generator is $100\%,$ calculate the power of the electricity produced. Write the assumption that is needed clearly.