I estimate the mouth of the Mississippi at 1 mile wide and 100 feet, or 0.02 miles, deep. If the water were moving at 10 miles an hour, that means that 10 miles x 0.02 miles x 1 miles flow through the mouth every hour.
10 x 0.02 x 1 = 0.2, times 24 hours/day = 4.8 cubic miles of water/day.
One assumption is that the tidal currents of the ocean can be neglected because within each 24-hour-period the tide rises and falls twice thus canceling out itself.
Back to Chapter 1.