Acre-foot

An acre-foot is a really big bathtub for water that measures how much water there is in a really big area of land. It's like a swimming pool, but for plants and animals to drink from, not for people to swim in.

Imagine a giant field that is one acre big (which is about the size of a football field without the end zones). Now imagine that we build a wall all the way around the field. We fill that enclosed area with water until it's one foot deep.

This amount of water is called an "acre-foot" because it can cover one acre of land to a depth of one foot. It's a way of measuring how much water we have in a really big area, and it's often used to measure the amount of water in reservoirs or lakes that provide water for cities and farms.