Shushtar, Historical Hydraulic System, is an island city from the Sassanian era with a complex irrigation system.
The river was channeled to form a moat around the city, while bridges and main gates into Shushtar were built to the east, west, and south. Several rivers nearby are conducive to the extension of agriculture; the cultivation of sugar cane, the main crop, dates back to 226 CE. A system of subterranean channels called Ghanats, which connected the river to the private reservoirs of houses and buildings, supplied water for domestic use and irrigation, as well as to store and supply water during times of war when the main gates were closed. Traces of these ghanats can still be found in the crypts of some houses. This complex system of irrigation degenerated during the 19th century.