It's typical to measure large surface areas in acres and the depth of water in a foot. So this seems like a very appropriate unit of measurement. An acre of w

It's typical to measure large surface areas in acres and the depth of water in a foot. So this seems like a very appropriate unit of measurement. An acre of water a foot deep. It makes thinking about large volumes of water easier - especially in the context of lakes and rivers. I have no clue how to begin thinking about 5,000,000,000 kiloliters or 130,000,000 gallons. But I can visualize an acre, and I can visualize a foot. Plus, think about rates of change. If 5 acre-foot of water is moving through a channel every hour, and you have a 500 acres reservoire, then the water level drops by 3 inches a day.