Abstract
Agriculture played a significant role in the economic prosperity and development during the Sassanid era. The Sassanid facilitated economic, social, and political growth by constructing water structures tailored to the environmental landscape of the region and establishing laws for water utilization. The presence of perennial rivers like the Dez and Karkheh in Khuzestan created conditions not only to supply the water needs of local settlements but also to address the shortage of drinking, industrial, and agricultural water in other areas distant from rivers that had fertile soil. This was achieved through the construction of structures such as weirs, canals, Qanats, and other water facilities. Specifically, the water supply for the city and agricultural lands of Gondishapur, located 15 kilometers from the Dez River, was accomplished through various water bodies; among these, river Qanats played a fundamental role in transferring reliable water from the Dez River to the city and its farmlands. Archaeological field studies conducted by the authors have led to the identification of new water structures, including weirs, Qanats, and related canals, which had previously been recognized only in part. A considerable portion of these structures is located on the eastern side of the Dez River, and some extend near Gondishapur, suggesting the hypothesis that river Qanats were the main source of water supply for this city-a notion traceable in historical writings. The primary question of this research is how the permanent water required by the city of Gondishapur was supplied, what role the river Qanats played, and what the physical relationship between the Qanats and the city was. The methodology of this research is historical-analytical, and the information gathering is based on field data and historical sources. Satellite imagery analysis indicates the prominent role of Qanats utilization in transferring water to Gondishapur from the Dez River during the Sassanid period, although some of the Dezful Qanats can be attributed to a later period, even the Safavid era.
Keywords: Aqueduct - Canal, Sater Structure, Dez River, Gondishapur, Dezful, Sasanian.

Introduction
Water, as a vital element, has played a central role in the development of civilizations. In Iran, a country with water limitations, this issue has gained double significance, and water engineering has been recognized as one of the most prominent aspects of Iranian technology and skill from ancient times to the present. The Qanats, one of the most astonishing achievements of water engineering in Iran, is regarded not only as a solution for managing scarce water resources but also as a valuable cultural symbol. These irrigation systems, some of which extend over a hundred kilometers, are renowned not only in Iran but also worldwide.
In this text, the author examines the engineering system and exploitation of underground waters in Dezful and its connection with the water supply of the city of Gondishapur and its surrounding lands. It is emphasized that a more accurate understanding of these systems can contribute to a better comprehension of the subsistence economy and economic development during the Sassanid and Islamic periods. Furthermore, analytical-comparative studies can demonstrate the level of creativity and the impact of these systems on the life of the city of Gondishapur.
The author has used descriptive-analytical methods and tools such as remote sensing, aerial and satellite imagery, maps, and digital elevation models to analyze the data. This research seeks to answer questions about the role of river Qanats in providing drinking, agricultural, and industrial water for the city of Gondishapur and how the technology and construction methods of these Qanats were.
The research hypotheses state that the water needed for the city of Gondishapur was supplied through the construction of weirs, Qanats chains, and open canals from the Dez River. Tangible evidence such as the Dezful weir, river Qanats, open canals, the siphon bridge of the Siyah-Mansur River, and the city’s piping with ceramic pipes are presented as examples of this technology.
This research not only assesses the historical and archaeological aspects of these systems but also pays attention to their importance in sustainable development and the preservation of cultural heritage. Ultimately, this study can serve as an important resource for researchers interested in the history and technology of water in Iran.

Discussion
The central question of the current research is how the perennial water supply needed by the city of Gondishapur was secured, what role the River Qanats played in this, and what the physical relationship between the Qanats and the city was like. The methodology of this research is historical-analytical, and the information gathering is based on field data and historical sources. Therefore, the forthcoming article examines and analyzes the engineering system and exploitation of underground waters in Dezful and how it relates to the water supply of the city of Gondishapur and its surrounding lands. It specifically seeks to answer the following questions: Based on historical and archaeological documents, how are the River Qanats evaluated in terms of providing drinking, agricultural, and industrial water for the city of Gondishapur? And what was the technology and construction method of the River Qanats of Dezful and their various components? Following these questions, the hypotheses of this research have been organized as follows: The water needed by the city of Gondishapur was supplied through the construction of weirs, Qanats chains, and open canals from the Dez River as a permanent water source. This action has been evidenced by the construction of the Dezful weir, river Qanats, open canals, the siphon bridge of the Siyah-Mansur River, and the city’s piping with ceramic pipes as tangible proofs of water transfer to the city of Gondishapur.

Conclusion
Field research and analysis of Corona aerial imagery have revealed numerous water structures in the northern, western, eastern, and southern areas surrounding Dezful. Among these, the Qanats located on the eastern bank of the Dez River hold particular significance due to their direct relevance to this study. For instance, no traces of Qanats are identifiable in the Yaqub-e Leyth region in the 1968 Corona images, yet two Qanats shafts were discovered during field investigations. A primary deficiency in the initial plan was the failure to identify the Qanats chains in the Benuarshami area. Following the discovery of ancient Qanats and canals, research began on their history, indicating that some Dezful Qanats, such as Qamish-e Momenun, might date back to the Safavid era. It appears that parts of these Qanats, ancient canals, and water structures supplying the city of Gondishapur were constructed at least in the latter half of the Sassanid period, or it cannot be said that all Dezful Qanats branches belong to a specific era.
It seems that in the first half of the Sassanid period, open earthen canals were responsible for supplying water to Gondishapur, and in the latter half, the introduction of new crops such as rice and sugarcane increased water demand, rendering the canals connected to the Dez River insufficient. This situation partly justifies the creation of Qanats. After the abandonment of the city in the 7th or 8th century AH, it is likely that the water supply structures of Gondishapur became ineffective. Consequently, the Qanats, whose water discharge was recorded until 1966 AD, transferred water to the western lands of Gondishapur or directed it downstream via the Siyah Mansur River.

Abstract
The Kur River basin, located in the Northwest of Fars province, is considered one of the main centers of the formation of the Achaemenid Empire. In terms of geographical landscape and climatic characteristics, the mentioned region includes vast intermountain plains (including Marvdasht and Korbal), rivers with deep beds (Kur and Sivand) and semi-arid climate. According to these conditions, the managers of Achaemenid economic-political institutions intelligently used the environmental capabilities of the region by building dams, weirs, Pool, reservoirs/catchments and canals to control surface waters and direct them to the ground. Agriculture and human settlements have paid. The dams and Weirs, while playing the aforementioned role, also prevented the damage to the agricultural lands located downstream by controlling the floods. The method of construction and selection of materials in the construction of structures has been different depending on the environment and their function. Dams and Weirs are mainly formed with an earthen core and a stone wall. The canals are also created in two ways: earthen and stone, or a combination of these two methods. The discussed structures have been attributed to the Achaemenid period, mainly based on their morphological features, type of materials, connection with the surrounding sites and comparative comparison with similar structures. The present study tries to introduce the Hydraulic Structures of the Kur River basin, its functional nature and morphological characteristics by using the descriptive-analytical method and by examining the evidences resulting from archaeological excavations and surveys. 
Keywords: Achaemenians, Kur River Basin, Hydraulic Structures, Canal, Agriculture.

Introduction
Central Fars region/Kur basin has a semi-arid climate with a Mediterranean rainfall pattern, most of which occurs in the winter season. New geological research and climate data show that during the Achaemenid period, the weather conditions of the Kur River basin were very similar to today (Djamali et al., 2009; Kehl et al., 2009; Rigot, 2010). Therefore, water control and management in a semi-arid environment with irregular rainfall patterns and rivers with deep beds has been vital and inevitable. According to these conditions, the managers of the political and economic institutions of the region have invested in the construction of structures such as dams, Weirs, reservoirs, and canals, whose works and evidence have been proven as a result of research and investigation. These Structures were built in different areas of the Kur River and with different purposes. The discussed structures in terms of dimensions and size, the amount of work and the materials used show the support and investment of the government. Therefore, the existence of various water structures, conducting targeted research in order to find out the functional nature of the structures, their physical structure and the reasons for assigning them to the Achaemenid period seems necessary. The main and important question of the current research is what was the function and performance of Hydraulic Structures in the Kur River basin during the Achaemenid period? What was the basis of the chronology and assignment of the studied water structures to the Achaemenid period? The structure, the environmental study and the geographical background of the formation of the structures have shown their various functions, such as supplying water to human settlements and agricultural lands, controlling and directing floods. Also, the discussed structures have been dated to the Achaemenid period, mainly based on their morphological features, type of materials, connection with the surrounding sites and comparative comparison with similar Structures.

Identified Traces 
As it was mentioned before, as a result of Archaeological investigations and researches, several important Hydraulic structures from the Achaemenid period have been identified and studied in the Kur river basin. In terms of morphological characteristics, the mentioned structures are divided into groups such as Dams, Weirs, Canals and Reservoirs. Among them, we can mention Band-e- Dokhtar, Bard Burideh II, Band-e- Bas II, Rahmat Mountain Canal, Asiyab Dam, Qondashloo Mountain Canal, etc. For the accurate dating of some of these structures (such as the band Dokhtar and the Bard Burideh), there is enough evidence, including the use of carved stone blocks and Dovetail Clamps. But some others can be attributed to the Achaemenid period based on possible evidence, including comparative comparison with similar structures and the connection with the surrounding sites. Band-e- Bas II and identified channels are included in this group. The precision and skill used in the construction of these structures indicate the existence of advanced engineering in the Achaemenid period. The chosen place for the implementation of Hydraulic projects reflects their functional nature. Therefore, it can be said that most of the Hydraulic Structures can be defined in connection with water supply and irrigation projects. The reason for the existence of Channels makes sense in this connection. Band-e- Dokhtar, Band-e- Bas and Asiyab Dam probably had a multifaceted function (irrigation, water supply and flood control). The Persepolis Tablets refer to a large amount of Agricultural and horticultural products in the Kur River basin. According to the texts of Persepolis, the diet of the people of this area in the Achaemenid period was mainly based on Agricultural products (barley and wine). Some of these crops can only be cultivated if irrigated. In addition, the implementation of irrigation projects has made it possible to plant nurseries and fruit gardens (mentioned in the Tablets).

Conclusion 
As the heart of the Achaemenid Empire, the Kur River basin has diverse environmental and geographical capabilities, including vast and fertile plains and permanent rivers. These natural characteristics have prompted the economic policy makers of the Achaemenid Empire to implement the economic programs of the Kur region according to its potential. The use and exploitation of surface water (rivers and springs) for the economic prosperity of the region by building structures such as dams, Weirs, canals and reservoirs is one of these measures. In this context, Band-e- Dokhtar and the canal branching from it, Bard Burideh II, Band-e- Bas II, Koh-e- Rahmat Canal, Koh-e- Qondashloo Canal, Koh-e- Ayyub Canal, Dezhabad-Amir Aqueduct are worth mentioning. The environmental study of the formation of structures and their placement in the landscape of the region shows that the main purpose of creating structures was to supply water to human settlements and Agricultural lands. The Persepolis Archive implicitly indicate the expansion and prosperity of agriculture/Gardening activities and diet based on agricultural products in the Kur river basin. Also, the reference of the Tablets to the cultivation of water crops (cotton, flax and rice) and various fruits can be considered as clear evidence of the role of water supply structures. The discussed structures have been attributed to the Achaemenid period, mainly based on their morphological features, type of materials, connection with the surrounding Sites and comparative comparison with similar structures. In terms of size and dimensions, the above structures show the amount of work and materials used for government support and investment.