Hydropower Engineering past question

During a low water week a river has an average daily flow of 40 m³/s with a fluctuation during the day required a pondage capacity of approximately 30% of the daily discharge. A hydroelectric plant is to be located on the river which will operate 6 days a week, 24 hours a day, but will supply power at a varying rate such that the daily load factor is 50%, corresponding to which the pondage required is equal to 0.2 times the mean flow to the turbine. On Saturday all the flow is ponded for use on the rest of the days. If the effective head on the turbines when the pond is full to 25 m and the maximum allowable fluctuation in pond level is 1m, find (i) the surface area of the pond to satisfy all the operating conditions (ii) the weekly output at the switch board in kwh. Assume turbine efficiency 80% and generator efficiency 90%. [5+5]