A hydraulic empire is an empire which maintains control over its population by means of controlling the supply of water.

Most of the first civilizations in history, such as Ancient Egypt and Mesopotamia were hydraulic empires. Most hydraulic empires existed in desert regions, but imperial China also had some such characteristics, due to the exacting needs of rice cultivation.

Because control over the vital resource of water gives the government power of life and death over its population, extreme despotism is typical of hydraulic empires - historically, many of these empires revered their rulers as gods. It also made popular revolution impossible - a dynasty may die out or be overthrown by force, but the new regime would be just as bad as the old one. Hydraulic empires were only ever destroyed by outside invaders.