Shushtar is a city in the province of Khuzestan and the center of the city of Shushtar. This city has an ancient history and civilization and was the center of Khuzestan province until the beginning of the Pahlavi period.

Its population is 139,000 and it is the 57th city in terms of population in Iran and Khuzestan province after the metropolis of Ahvaz and the cities of Dezful and Abadan is the fourth city in terms of population.

Naturally, the last slopes of the Zagros Mountains form the eastern border of the city and the Dez River forms the western border of the city. The average height of the city of Shushtar is 150 meters above sea level, and the height of the central point of the city of Shushtar is 65 meters above sea level.

The water structures of Shushtar have made Shushtar one of the tourist centers (UNESCO World Heritage Site). Shushtar infrastructure included water mills, dams, tunnels, and canals. Gargar Bridge-Dam was built on the watermills and waterfalls. Bolayti canal is situated on the eastern side of the water mills and water falls and functions to supply water from behind the GarGar bridge to the east side of water mills and channel the water to prevent damage to the water mills. Dahaneye shahr tunnel (city orifice) is one of the three main tunnels which channeled the water from behind the Gargar Bridge-Dam into the water mill and then run several water mills. Seh koreh canal channels the water from behind the GarGar Bridge into the western side. In the water mills and water falls, we can see a perfect model of haltering to run mills.