Water Resources Management, Technology, and Culture in Ancient Iran

Abstract. Iran is one of the countries facing high water risk because of its geographical features, climate variations, and uneven distribution of water resources. Iranians have practiced different water management strategies at various periods following the region's geo-climatological features, needs, tools, available resources (surface water and groundwater), political stability, economic power, and socio-cultural characteristics. This study is a brief history of water management in Iran from pre-civilization times to the end of the Islamic Golden Age (1219 AD). This study pointed out geo-climatological features have consistently been crucial intrinsic properties controlling water regime, settlement patterns, and other socioeconomic issues. These factors caused the early agricultural communities to emerge in water-rich regions of northwestern, western, and southwestern Iran. By the 4th Millennium BC, while water access became more difficult as population growth, economic activity, and urbanization progress, water resources' systematic development appeared in west and southwest Iran under the Mesopotamian civilization. However, despite all benefits, Mesopotamian water-based technology and administration could not meet all water demands in Iran's arid regions. For these reasons, qanats were developed in Persia by the First Persian Empire (Achaemenid Empire). No doubt, the Achaemenids (550–330 BC) should be regarded as one of the early civilizations that emerged in a land without sufficient rainfall and major rivers. In this time, idle and marginal lands of Iran and neighboring regions of the Middle East, North Africa, and Central Asia could be cultivated through the spread of qanat technology, enabling large groups of peasants to increase crop yields and incomes. After a period of recession during the Seleucid Empire (312–63 BC) and the Parthian Empire (247 BC–224 AD), water resources development gained momentum in the Sassanid era (224–651). In this period, the progress of urbanization was expeditious. Consciously, water resources development in Khuzestan plains (Shushtar and Dezful) was crucial for agricultural intensification, economic expansion, and civilization development. The Sassanids wisely adapted Greek watermills to the complicated topography, limited water availability, and variable climate of Iran to produce food. Although the Iranians practiced a new era of water governance under the Sassanid rule (224–651 AD), chaotic Iran in the Late Sasanian and Early Islamic Period led to severe weaknesses in water-related sectors. After Islam's arrival, the Muslim rulers turned their attention from fighting to set up an Islamic civilization to break the socioeconomic stagnation. To achieve the goal, they opened their scientific doors to science and technology centers. Despite all efforts made during the 8th–12th century, the lack of creativity and investment in promoting water technologies, prioritizing political considerations over social benefits, occurring wars, and poor water management have induced the Iranians to lose their power in developing water resources. In today's Iran, the past water-related problems have aggravated by uneven climate change, population rise, rapid industrialization, urban development, and unprecedented changes in lifestyle. Undoubtedly, solving these problems and moving towards a better future is not possible without addressing the past.


an inlet canal, two sidewalls, and a front wall made by baked bricks. Water was stored and desilted in the reservoir 146 and transferred to a basin through nine conduits situated at the bottom of the front wall. Each conduit had two 147 inclined surfaces. The distance between the two neighboring conduits was 0.8 m. As the basin had higher elevation 148 than the conduits, earthy materials were removed from the body of water (Sanizadeh 2008). When the pond was 149 fully recharged, the filtered water was diverted to the temple. In the temple, water was distributed by a network 150 of gutters for worship and purification rituals.

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In 550 BC, Cyrus the Great established the First Persian Empire (the second Iranian empire-based Dynasty after 185 the Median Dynasty) called the Achaemenid Dynasty (Sampson 2008) in the land of "Pars" 17 or "Persis" 18 . The

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Achaemenids built the earliest Persian civilization to be socially organized, politically stable, economically firm, 187 and militarily strong (Sampson 2008).

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In Early Achaemenid Iran, the Persians were semi-nomadic tribes 1920 guided by unsophisticated tribal  A critical step in qanat construction is to find a reliable groundwater resource (Boustani 2008).

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Landscape, anomalies in soil color and moisture, seepage pattern, vegetation cover, and spring discharge are 212 conventional indicators to locate a qanat construction point. Ancients presumably knew groundwater could be 213 available in foothills, wadies, dry riverbeds, and alluvial fans (Waterhistory 2019). After viewing evidence, the 214 first and deepest shaft named the "mother-well" is dug by a crew of skilled qanat diggers 28 using only simple hand 215 tools 29 . The mother-well is sunk to the saturated zone for locating the water table and checking the quality, 216 quantity, and regularity of the groundwater flow (Kheirabadi 2000;Smith 1953). In this stage, the aesthetic 217 parameters of water (i.e., temperature, turbidity, color, taste, and odor) are detected by qanat diggers through the 218 senses. The sense of hearing is occasionally used to detect water movement.

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In the next step, along a line between the mother-well and qanat outlet, the crew digs vertical shafts with  shaft lining is necessary to improve the qanat durability.

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The mother-well depth depends on the water table depth, qanat length, earth slope, and the owner's 228 capital for excavation, ranging between 30 m and 100 m (Karki et al., 2017). The qanat length could also be either 229 short or long, varying from a few hundred meters to ∼100 km. In qanat design, the slope is one of the most critical 230 factors that controls a qanat's length. Gradients from 2/1000 to 5/1000 will typically provide sufficient flow Desert) in the south-central part of Iran (English 1968).

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The origin and outspread of qanat have been discussed by many researchers such as Kobori (1973),

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Labbaf Khaneiki (2016). As archaeological records provide little information on the qanat's origin, there is still 239 no widely accepted hypothesis to explain this topic. The earliest written evidence is some inscriptions on stone 30 (Lückge et al., 2001). For this reason, qanat seems to 247 be an adaptive response to climate change and water shortage.

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Like other water-related systems, qanat has its own advantages and disadvantages (Table 2). From a 250 social view, qanats can be considered one of the key indicators to determine how and where ancient people lived.

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It seems that most ancient qanats in Iran were constructed in the central, eastern, and southeastern regions of the 252 Iranian Plateau with a dry climate (e.g., in present-day Kerman, Hormozgan, Sistan and Baluchestan, South

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Khorasan, and Yazd provinces) ( Figure 5). Although these regions have a lower population density than the 254 country average, they contain many qanats due to their water shortage. According to Briant (2002), further 255 expansion of qanat technology in these areas led to the emergence of the whole season agriculture, thus ensuring 256 an increase in agricultural intensification, food supply, and income. The qanat practice was not usual in water-257 rich regions (e.g., Khuzestan, Gilan, and Mazandaran) unless surface water resources were fully exploited or 258 depleted during long-term droughts. Unlike a water well, qanat systems did not have a point structure; these systems covered the land of many 264 hundred farmers with unequal shares (Kobori 1973). Hence, a relationship between the government, local owners, 265 and sharecroppers were essential. On occasion, the qanats' linear structure caused controversy over the water 266 distribution from upstream to downstream, especially during water shortage periods (Saatsaz 2019). Besides, the 267 approximation of the buffer zone along the route of each qanat and assessing the owner's contribution to dig, 268 maintain, and restore a qanat, was challenging. The water allocation challenges existed not only in the past but 269 also in the present. The Achaemenids were aware of this and made all efforts to protect, clean up, and rehabilitate 270 qanats through peaceful collaborations. Because of the people's dependency on qanats, the Achaemenid's 271 government also performed many remunerations and incentive policies for renovating an abandoned qanat. One

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The Achaemenid Empire was thinking about qanat development but, for many reasons, tried to construct dams.

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As the Achaemenids strengthened, there was an increasing demand for water supply, irrigation, flood control, and

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Since the Marvdasht Plain's river level was lower than the surrounding areas, it was impossible to use 304 any water from the streams without artificial assistance and technical installations. Also, the drainage system in  reservoirs, and networks of water canals to keep rivers safe, store floodwater, divert water, and supply water.

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All the stones were local and quarried on the spot. The dam structure is very similar to "Sad-el Kafarathe Dam," 323 built in ∼the 3 rd Millennium BC by the ancient Egyptians for flood control (Smith 1971).

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Another major dam, Sad-e Shahidabad, was built on the Polvar River in the "Tangeh Bolaghi Area" in

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The Achaemenids realized that rainfall and rivers in their territory are insufficient for a secure water

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Undoubtedly, the Achaemenids had many other reasons for building the dam. As found in an Old Persian 357 cuneiform text, Darius the Great asks God to protect the land of Persia from the lie, enemy, and famine. The 358 drought meant water shortages, and water shortages meant starvation for them. Assuming the past climatic 359 conditions equal to that in the present, we tried to find the cause of these concerns. First, the moving average of 360 precipitation for three, five, and seven years have been calculated in a period between 1973 and 2016 (e.g., three 361 years moving average of rainfall for a specific year is equal to the average total rainfall in that year, the previous 362 year and the following year) (see Appendix). In the next step, maximum duration, magnitude, intensity, and 363 severity for drought events were determined (Table 4).  Table 4 shows that the 371 average maximum severity and duration of droughts in the Marvdasht Plain are classified as moderate and very 372 severe. By occurring such drought, however, the climate of the area moves towards an unfavorable arid regime.

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If such conditions prevail over the whole country, the climate in more than 65% of the country changes towards 374 a hyper-arid regime. Under such circumstances, drought will be a serious threat to food security. This justifies the 375 Achaemenids' great attention to dams.

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The Achaemenids, regardless of all the weaknesses they had at the end of their 220-year reign, could 378 make great achievements, particularly in water-related sectors. Some of their achievements were destroyed by 379 natural and man-made disasters, some were reconstructed by other empires and labeled by their names, and some 380 are still in use. However, the most important achievement of the Achaemenids is creating "national identity"; a 381 concept that water played a crucial role in shaping it.

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Following the conquest of Iran by Alexander the Great in 330 BC, the Iranian satraps 47 were governed by various

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Greek Satraps forming the Hellenistic Seleucid Empire and then Parthian Empire 48 (Curtis 2007). After the 386 conquest of Iran by Alexander, qanats seem to have been abandoned or destroyed (Ashrafi and Safdarian 2015).

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Moreover, since the Parthian government was remarkably decentralized, the Parthians were not concerned about 388 the loss of qanats and other hydraulic structures. According to Semsar Yazdi (2006), some qanat systems and 389 irrigational systems were abandoned or damaged. Polybius, a Greek historian of the Hellenistic period 49 , recorded 390 that Arsaces III, one of the Parthian kings, tried to destroy some qanats and interrupt water flow to make it difficult 391 for the Seleucids to advance towards the Parthian capital 50 (Beaumont 1971).

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The Sassanid's regulations had excellent attention to groundwater, especially to issues concerning the management 396 of qanat. The Sasanian Empire realized that water resources' administration provides them the strength, stability, 397 and durability. Hence, they established the first specific department of water called "Diwan-e Kastfezoud" (also

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The Sasanians tried to be an urban dynasty through the building and re-building of many cities. They 409 constructed many weir-bridges 52 in both Persian and Roman styles ( Table 5). The doctrine of urbanization allowed mighty rivers, and agricultural lands, had a unique chance for development 55 .

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The first multipurpose weir-bridge, called Band-e Kaisar" 56 , was built by the Sassanid's in the north-west 415 part of Shushtar over the Shoteit River, the main branch of the Karun River 57 . This weir was used as a bridge for

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Since the Sassanid Empire, "Greek Mill" and "Roman Mill" have been used to meet the needs. The so-443 called "Roman Mill" features a vertical wheel, rotating about a horizontal shaft. Unlike the Roman type, a "Greek 444 Mill" is powered by a horizontal wheel, rotating around a vertical axle or shaft, without setting up gears. This type 445 is generally powered by small water volumes directed at high-velocity (Weaver and Pinder 1963). An inclined 446 aqueduct diverts a proportion of water from a river toward the water-mill in these mills. From a height of one to 447 20 m, the water drops into a reverse cone-shaped water-tower to provide a pressure head for driving the wheel.

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At the bottom of the water-tower a convergent nozzle with varying cross-sectional areas is used to eject the water  Greek water-mills, such as those that were constructed in Khuzestan, Ilam, Fars, and Khorasan, were 472 built below weirs. A typical style was pair water-mills in which two sets of water-mills, with one headrace, were 473 used in two neighboring rooms separated by a wall. This mill was designed for grinding two kinds of grains at the 474 same time. In fast-flowing permanent rivers, a string of water-tower mills, fed by a small canals system, was 475 occasionally constructed at irregular intervals ranging between ∼50 m to 1,500 m (Neely 2011;Harverson 1993).

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The remnants of a string of 22 pre-Islamic water-towers, covering a total distance of ∼6.5 km, are traceable in the

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Qanat-based water-mills can be regarded as an appropriate technology for sustainable development. They

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In Iran, Roman water-mills have been mostly constructed along large rivers, such as "Zayandeh-Rud 90 ", 501 and Karun. Occasionally, a complex of Roman water-mills was built in different sections of a river corridor.

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Midstream water-mills were operated in dry seasons and riverside in both wet and dry seasons. Roman water-503 mills was customarily set into two primary levels; a basement for housing the drive system (wheel-house) and a 504 top floor for millstones (grinding room). The grinding room roof was occasionally domed, allowing the air to 505 circulate and light to transmit through the dome openings. The packs of grains were stored in an attic, connected 506 to a hopper to pour grains into the millstones. One of the oldest stream mills 91

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Through watermills, the Sassanids could introduce a cost-effective, eco-friendly, and sustainable 511 technology to the Iranians. Flour made by a watermill was tasty and fresh; it kept for years without spoiling. It   (Table 6), these systems can be used to generate green energy after rebuilding and 523 reviving.

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Although the Sasanian's Era was a golden age for the Iranians in terms of agricultural activity, urban development,

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The sharp decline in agricultural production led to a reduction in the country's tax revenue. Decreased attention 535 to the country's water infrastructure caused severe floods. In total, the food and economic security of the country 536 was severely endangered. The Sassanids declined like a living creature that decays at the end of its life.

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In cases, there were some contradictions between Islamic rules and traditional customs. In the Islamic 550 view, water, land, and crops as indivisible, interrelated, and interdependent properties. According to the precepts 551 of sharia, water cannot be possessed by anyone; it is a free substance, and beyond private ownership, no price 552 should be paid to use it, and it cannot be sold. Riparian water rights for allocating water have commonly been 553 limited to amounts measured adequate for a particular crop area (Naff 2009). Such a condition was in stark contrast 554 to the Sassanid's system. The Sassanid Empire had a rigid social stratification in which social classes differed in 555 terms of dignity, rank, right, ownership, and control of sources, wealth, and social activities . In this 556 system, nobles and priests lived in a luxurious form, incomparable to a farmer's life. This form was utterly different 557 from that of Islam that emphasized justice, equality, and fairness. To establish an Islamic system, great flexibility 558 was needed to reach a compromise with Iranians. In some cases, Muslim jurists had to ignore their laws or make 559 slight changes in former Iranian laws (Wilkinson 1990).

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Although agriculture remained the base of economy and society in the early Islamic period, investment

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In a long period between the 8 th to the end of the 12 th century 101 , the Muslim world underwent a golden 569 age of advancement in science, agriculture, economy, art, architecture, and literature (Saliba 1995). During the 570 period, Muslims increased their scientific collaboration with Greek, Roman, Chinese, and Hindu scholars 102 . At

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During the period, new water infrastructures were built, and old ones were reconstructed. Among the 588 small dams and bands that were built in this period, the Buyids dams of "Qur'an Gate," 108 "Band-e Air," "the 589 Ghaznavid's dams of "Feiz Abad" and "Tous" 109 , and the Ilkhanate's dam of "Kebar" 110 can be mentioned  (Table 7). Despite all efforts 592 made during this period, the lack of creativity and investment in promoting water-related infrastructure and 593 technologies, occurring wars and territorial conflicts, prioritizing economic and political concerns over social 594 benefits along with poor water governance have resulted in water insecurity over centuries.

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This study shows that, except for the Achaemenids and Sassanids, leaders and policy-makers could not 631 stimulate the Iranians to innovate and enhance their water technologies, services, or management practices. During 632 the Islamic Golden Age, the Iranians' focus was mainly on science's theoretical development; they did not solve 633 water-related problems practically with the times. For instance, the Iranians did not try to reduce the systematic 634 disadvantages of the qanat over time. Following an acceleration in population growth, industry expansion, lifestyle 635 change, and urbanization, the qanat system was ineffective. It was unavoidably marginalized and swapped by

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There are many other lessons to learn. In ancient Iran, water-related problems were solved by basic 642 concepts of Hydraulics. In the same way, water-related infrastructures were built using locally available materials.

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Still, these managing practices and technology constituted the necessary foundations for today's water governance.

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However, although water rights, fairwater allocation, pricing plan, sustainable use, public service, social 645 responsibility, quality criteria, social benefits, use efficiency, water integrity, and water governance have been

BC
Alexander the Great captured Iran, destroying thousands of qanats and irrigation systems.

-331 BC
The Greeks ruled over Iran through the Seleucid Empire and Parthians. In this period, some qanat and irrigational systems were abundant or damaged.

BC-224 BC
The Sassanids established the first department of water named "Dīwān-e Kastfezoud." In this era, many dams and weirs were constructed and rebuilt or their mills repaired.

BC -642 AD
The implementation of Islamic customs and laws in water-related affairs. 642 AD Iranians experienced a "Golden Age" of science and showed keen interest in assimilating other nations' scientific knowledge, writing and translating books.  Creating controversy over the approximation of the buffer zone, water allocation and distribution Application to transport water over long distances; Allowing the government to utilize barren lands purposefully. Making a significant relationship between the government, local owners, and farmers for constructing, maintaining and reviving qanats. Applying digging-related experiences in the military to build underground tunnels for smuggling and defensive purposes; allowing the Achaemenids to extend their authority to farther regions

Agricultural and Economic Aspects
The emergence of the whole season agriculture To be relatively time-consuming, labor-intensive, and expensive for the construction, maintenance, and repair of qanats The increase in agricultural products, food supply, and income; allowing the people to be empowered socially and economically. Proving service to many caravans, on oases along the Silk Route, developing economic, and cultural trade.

Hydrological Aspects
Insensitive to seasonal and other short-time changes in weather Having a non-stop discharge during all seasons Extracting groundwater as a renewable resource without making rapid drawdown in the aquifer Not possible to construct in flat areas Supplying cold freshwater with low turbidity, and water loss.
Extreme floods and earthquakes can severely damage, or obliterate the qanat shafts and tunnel.
Using the energy of gravity for water transferring without the need to pump or other forms of energy. Providing energy through watermills Collecting surface runoff through the vertical shafts and reduce the risk of flash floods. The ability to store the qanat water into small reservoirs for later use.    Mizan Weir, with a length of 390 m and a height of 4.5 m, was built in the form of diagonal walls, in the North of Shushtar to the diverts the Karun River water to its branches (i.e., Gargar and Shoteit). Remained walls confirm the existence of watermills in the past on the weir's eastern section. In the western part of the weir, an octagonal tower named "Kolah Farangi Tower" is built to monitor the process of weir design and construction. An octagonal tower called "Kolah Farangi Tower" is created to monitor the operation of weir design and construction.

Gargar River (Shushtar) Band-e Mizan
Gargar Weir, at the northeast of Shushtar, is extending from east to west. The weir dimensions are 83 m long, 12 m wide, and 6 m high. This weir is constructed to divert the Gargar River water to the watermills, residential areas, and irrigation canals. The Gargar connects the Karun in Band-e Ghir, 44 km south of Shushtar. Gargar Weir was renovated in the Safavid Era.

Gargar River (Shushtar)
Band-e Gargar Borj-e-ʻAyār weir, 7.30 m long and 3.50 m wide, lies across the Gargar River, at the southeast of Shushtar. There is a pond related to the Sabein (Mandaeists 4 ) Temple, several historic watermills, and related canals around the weir. The weir was constructed to raise the water level in irrigation canals and provide water for watermills and temple. At present, a small part of the weir is preserved, and other parts are ruined due to road construction.

Gargar River (Shushtar)
Band-e Borj-e-ʻAyār (Sabei Kosh) Khoda Afarin, with a length of 500 m, and width-height of two m, was built south of Shushtar to bring up the water level in irrigation canals and link between two sides of the Dariyon River.

Dariyon River (Shushtar)
Band-e Khoda Afarin (Band-e Mahibazan) One of the famous hydraulic structures attributed to the Sassanids is Lashkar Weir, which is set up to divert water to the lands in the south of Shushtar. This structure has 104 m in length, eight m in width, and 11 gates, stand on solid columns of mortar, brick, and stone.

Dariyon River (Shushtar)
Band-e Lashgar (Polband-e Darvâzeh) Sharabdar Weir, with a length of 35 m, a width of 2 m, and a height of one m, lies in an east-west direction across Raghat Stream 5 . This weir has been built to adjust the water level in irrigation networks.

Dariyon River (Shushtar) Band-e Sharabdar
This weir is located along the Shiraz-Firuzabad Road in Fars Province, spanning the Qara Aqaj River that flows towards the Persian Gulf. With a length of about 130 m and a height of about 9 m, the weir was constructed to raise the Qara Aghaj water level and direct its flow to Kavar Plain through a canal built in the weir's eastern corner. The weir materials are pieces of natural mountain stone and mortar.

Qara Aghaj River (Kavar)
Band-e Kavar (Band-e Kuar, Band-e Bahman) Dezful weir-bridge, with 22 arches, was set up over the Dez River to link the western and eastern parts of the city and provide water for agricultural areas and gardens of Dezful. Although the weir strong and durable structure, it was substantially damaged by a great flood in 1903.

Dez River (Dezful) Polband-e Dezful
Khak Weir, at the southwest of Shushtar, was constructed to prevent the Dariyon River and its neighboring plains from flooding and divert water to its branches. This weir was damaged during road construction activities.

Dariyon River (Shushtar) Band-e Khak
This weir is located across the Ahvaz Anticline over the Karun River. The weir collapsed at an unknown time in antiquity. At present, only the wall bases of the weir and traces of mills on the end walls of the weir have remained.