Consider two reservoirs, A and B, connected in series with reservoir A situated upstream of reservoir B. The surface area of A is half of B. The area of B is 40 km2. Both reservoirs A and B are subject to a total rainfall of 50 cm and evaporation of 30 cm on an annual basis. To preserve the ecological environment in the riparian zone along the water course, reservoir A is required to release a constant flow of 0.1 m3/s to reservoir B, whereas reservoir B releases 0.3 m3/s to its downstream channel. At the present time, other than the in-stream flow requirement, there is no manmade structure withdrawing water from reservoir B. A small town of 50 000 is located near reservoir B. The per capita water consumption is 400 liters per day. The town is contemplating to use reservoir B as a water supply reservoir. a) Determine the annual water storage change of water (in cm) in each of the two reservoirs if water is to be delivered from reservoir B to satisfy the water consumption stipulated above.
b) To maintain the required in-stream flow requirement and per-capita consumption as stipulated above, for how long can this reservoir supply water to the town?
c) If the annual water storage change in reservoir B cannot be negative, how much of the percapita consumption has to be adjusted?