Shushtar Historical Hydraulic System is an island city from the Sassanid era with a complex irrigation system, situated in Iran's E4851 N3202 in Khuzestan Province. It has been registered on UNESCO's list of World Heritage Sites in 2009, as Iran's 10th cultural heritage site to be registered on the United Nations' list. The famous French archaeologist Jane Dieulafoy considers this area as the largest industrial complex before the industrial revolution.

The Shushtar water mills are the best ones which were to use water in ancient periods. These include a collection of dams, tunnels, ancillary canals watermills which utilized as Industry–Economic collection. Gargar weir was built on the watermills and waterfalls, that abstract don storms the Gargar branches and has a function similar to up to date dams to lead the water in the tunnel of watermills. Bolayti canal is situated in the eastern side of the watermills and waterfalls. The function of this canal is to supply the water from behind the Gargar bridge to the east side of watermills to prevent the damage to the watermills. Dahaneye shahr tunnel (city orifice) is one of the three main tunnels which channelled the water from behind the Gargar weir into the water mill and then run several watermills. Seh koreh canal channels the water from behind the Gargar Bridge into the western side. In watermills and waterfalls, there are noticeable mills we can see a perfect model of haltering to run mills.

The Band-e Kaisar ("Caesar's dam"), an approximately 500-metre (1,600 ft) long Roman weir across the Karun, was the key structure of the complex which, along with the Band-i-Mizan, retained and diverted river water into the irrigation canals in the area. Built by a Roman workforce in the 3rd century AD on Sassanid order, it was the most eastern Roman bridge and Roman dam and the first structure in Iran to combine a bridge with a dam.

Parts of the irrigation system are said to originally date to the time of Darius the Great, an Achaemenian king of Iran. It partly consists of a pair of primary diversion canals in the Karun River, one of which is still in use today. It delivers water to the Shushtar city via a route of supplying tunnels. The area includes Selastel Castel, which is the axis for the operation of the hydraulic system. It also consists of a tower for water level measurement, along with bridges, dams, mills, and basins.

Then it enters the plain south from the city, where its impact includes enabling the possibility of farming over the area called Mianâb and planting orchards (over an area of 40,000 ha). The whole area between the two diversion canals (Shutayt and Gargar) on Karun River is called Mianâb, an island having the Shushtar city at its northern end. The site has been referred to as "a masterpiece of creative genius" by UNESCO.

Project System and Heritage Composition

The Shushtar Historical Hydraulic System demonstrates outstanding universal value as in its present form, it dates from the 3^rd century CE, probably on older bases from the 5^th century BCE. It is complete, with numerous functions, and large-scale, making it exceptional. The Shushtar system is a homogeneous hydraulic system, designed globally and completed in the 3^rd century CE. It is as rich in its diversity of civil engineering structures and its constructions as in the diversity of its uses (urban water supply, mills, irrigation, river transport, and defensive system). The Shushtar Historical Hydraulic System testifies to the heritage and the synthesis of earlier Elamite and Mesopotamian knowhow; it was probably influenced by the Petra dam and tunnel and by Roman civil engineering. The Shushtar hydraulic system, in its ensemble and most particularly the Shâdorvân Grand Weir (bridge-dam), has been considered a Wonder of the World not only by the Persians but also by the Arab-Muslims at the peak of their civilisation. The Gargar canal is a veritable artificial watercourse which made possible the construction of a new town and the irrigation of a vast plain, at the time semi-desert. The Shushtar Historical Hydraulic System sits in an urban and rural landscape specific to the expression of its value.

The Shushtar Historical Hydraulic System retains a high level of authenticity and integrity as a comprehensive and continuing functional system. The natural environment and significant characteristics of the System can be considered completely intact since ancient times. The system truthfully represents the technological innovation and function of the system in its entirety. Despite the passage of time, natural weathering, modernization, the Shushtar Historical Hydraulic System has always continued to serve the functions for which it was created. This was guaranteed through regular maintenance, conservation and valorization. During its life of more than 2,000 years, the functions of the Shushtar Historical Hydraulic System have evolved through the development of technologies. For example, the first industrial electricity distribution centre in Iran was established within the Shushtar Historical Hydraulic System, which integrated some alterations to the facilities within the system. These interventions, however, have been integrated in a compatible and harmonious manner, demonstrating the evolution of the traditional functions of the System. The main objective and function of this system have always been to manage the hydraulic energy and water resources sustainably, respecting the environment, as well as the needs of the local communities. The continuous agricultural, economic, industrial, trading and cultural life of Shushtar region also testifies to the fact that the System has been continued. Moreover, the authenticity of this System can be seen in all its elements including, design, workmanship, location, setting, function and materials. There are no significant alterations or destructive interventions in this System.

Water Heritage

1. The Shushtar Hydraulic System is testimony to a remarkably accomplished and early overall vision of the possibilities afforded by diversion canals and large weir-dams for land development. It was designed and completed in the 3rd century CE for sustainable operation and is still in use today. It is a unique and exceptional ensemble in terms of its technical diversity and its completeness that testifies to human creative genius.
2. The Shushtar Historical Hydraulic System is a synthesis of diverse techniques brought together to form a remarkably complete and large-scale ensemble. It has benefited from the ancient expertise of the Elamites and Mesopotamians in canal irrigation, and then that of the Nabateans; Roman technicians also influenced its construction. Its many visitors marvelled at it and were in turn inspired. It testifies to the exchange of considerable influences in hydraulic engineering and its application throughout antiquity and the Islamic period under the various Iranian dynasties.
3. Shushtar is a unique and exceptionally complete example of hydraulic techniques developed during ancient times to aid the occupation of semi-desert lands. By diverting a river flowing down the mountains, using large-scale civil engineering structures and the creation of canals, it made possible multiple uses for the water across a vast territory: urban water supply, agricultural irrigation, fish farming, mills, transport, defence system, etc. It testifies to a technical culture dating back eighteen centuries serving the sustainable development of human society, in harmony with its natural and urban environment.

Present State of Conservation

The protection of all historical sites and monuments of Iran is ensured by ICHHTO. According to the Law of Conservation of National Monuments and Sites, all the monuments and sites registered in the National Heritage List are under the Government’s protection and supervision. The legal implementation of these regulations is ensured by Clause 2 of the Decree of the National Security Council as well as Paragraph ‘C’ of Article 166 of the Law for the Third Five Year Development Plan of the Law for the Fourth Five Year Development Plan. These articles emphasize the protection of ancient remains within modern settlements.

Shushtar Historical Hydraulic System involves 13 main properties. All 13 properties have been registered on the list of the National Heritage Monument of Iran. By registering these properties on the National Heritage List of Iran, these properties enjoy special protection and conservation legislation.

Physical protection of the properties is ensured by the ICHHTO corps of guards. The guards employed by the local office of the ICHHTO are present on the sites, ensuring permanent surveillance of the properties. Another effective means of protection is secured by the inhabitants of this property and respective NGOs.

The ICHHTO Shushtar Historical Hydraulic System Base was established in 1999. Since then, all protection, preservation, restoration, research and tourism management actions have been planned and implemented with the approval of the Base, and also closely monitored by the supervisory bodies explained below. Notification of the national registration of the cultural heritage properties of SHHS has been transmitted by ICHHTO to all relevant state authorities and bodies, informing them of the laws which apply to these properties. This notification is to ensure that any actions which may impact upon the properties are authorized by ICHHTO before planning and implementation.

The first master plan of Shushtar dates back to the year 1364 AH (1985) which was drawn up and approved by Zista consulting engineers in about 600 pages largely concerning the preservation of Shushtar historical monuments. Afterwards, the same consulting organization prepared another master plan in 1367AH (1988) and drew up the 400 paged Rehabilitation and Maintenance Plan of Historical Fabric of Shushtar in 1371AH (1992) which was ratified by the high council of Iranian Ministry for Housing and Urban Development. Among its specifications is documentation of historical elements as well as giving special attention to historical conservation which effectively prevented damages inflicted upon Shushtar historical monuments. In this plan, the preservation of the historical visual characteristics of the city is emphasized.

Since 1384 AH (2005) reconsideration of Shushtar master plan by the Iranian Ministry for Housing and Urban Development has started. Among its specifications is the observance of legal regulations regarding cultural heritage buffer zones declared by ICHHTO.