Qanat-based watermills are material expressions of how rural communities in Iran adapted production technologies to arid and semi-arid environments. By combining subterranean water conveyance, controlled differences in elevation, vernacular construction, and locally organized ownership, they converted the continuous flow of a qanat into mechanical energy without consuming the water required downstream for irrigation. Their importance was not confined to grinding grain. A watermill could operate simultaneously as a productive facility, a transferable asset, a source of rent, a workplace, a meeting point, and an element in the spatial organization of a village and its orchards.

These functions declined rapidly after the spread of diesel and electric mills, changes in agriculture and transport, rural out-migration, and reduced dependence on qanats. Once a mill ceased operating, its water channels, pressure shaft, working chamber, access route, and connection with the qanat were often neglected, altered, or buried beneath later construction. A mill studied only as an isolated building is therefore incompletely understood. Its meaning depends on the hydrological route, topography, agricultural land, settlement pattern, ownership relations, and memories of use that surround it.

Sarkhong is a mountain village about three kilometres north of Qohestan in Darmian County, South Khorasan Province. It lies at approximately 2,100 metres above sea level in a cold semi-arid environment. Five qanats historically supplied the settlement and its orchards. Local testimony and documents indicate that seven watermills operated within the study area: five near the village and two along the orchards toward Derakhsh. They processed grain for Sarkhong and settlements within an estimated radius of 20–30 kilometres. Most declined during the 1960s, while the Haji Molla Mohammad Mill continued until approximately 1972 or 1973.

Previous studies have documented the architecture and mechanical operation of Iranian watermills or considered watermill landscapes and adaptive reuse elsewhere. Less attention has been paid to the simultaneous relationship between location within a qanat system, ownership and leasing, endowments, local narratives, and present heritage condition. This study addresses that gap through an integrated geographical, documentary, and anthropological reading. It asks how topography and qanat flow shaped mill location; how the mills were owned, transferred, and connected with the village economy; what social and religious meanings they carried; and what priorities should guide conservation. It does not assume that restoration will automatically generate tourism or employment, but seeks to establish a reliable basis for future decisions.

Methods

The research was designed as an in-depth case study using a descriptive-analytical and historical approach. Quantities derived from documents and field measurements were used descriptively and did not constitute a separate quantitative phase. Three bodies of evidence were assembled: field observations and spatial measurements, unpublished historical documents, and semi-structured interviews. Triangulation was essential because physical remains, documents, and oral histories each preserved different and incomplete aspects of the former mill system.

Fieldwork began with identification and documentation of visible remains. Each site was examined in relation to the qanat route, orchards, settlement areas, and local relief. A multi-frequency satellite positioning receiver collected location and elevation data from the qanat emergence point through the study corridor. A longitudinal profile was prepared, and changes in slope were compared with recorded mill locations. This helped determine whether sites identified in documents or interviews were compatible with the hydraulic requirements of qanat-powered milling.

Fifteen semi-structured interviews were conducted in 2024 with knowledgeable local residents aged 60–90. Some still lived in Sarkhong, while migrants were interviewed by telephone. Participants were recruited through snowball sampling: initial informants identified others with direct or family knowledge of mill operation, ownership, water distribution, social activity, or abandonment. The study purpose was explained before each interview and verbal informed consent was obtained. With permission, information was captured by audio recording, contemporaneous notes, or both. Participants were assigned codes P01–P15. Questions addressed mill history, number and location; operation, ownership, leasing, and benefit sharing; relations between owners and millers; social and religious functions; and causes of decline.

Accounts were organized by theme and compared with field evidence. Contradictory memories were retained rather than forced into one narrative. When different locations were proposed for a vanished mill, they were checked against qanat alignment, elevation change, and surviving traces. Locations lacking sufficient corroboration remained uncertain.

The documentary corpus comprised 11 historical records, including leases, sale deeds, endowment documents, ownership records, and powers of attorney, mainly preserved in family archives. For each record, the date, document type, mill, parties, share or property, payment or rent, and public or religious function were extracted. Local measures were interpreted cautiously. In Sarkhong, one man comprised 40 sir, each equal to approximately 9.5 mithqal, or 380 mithqal in total (about 1.78 kilograms). The unit is used only to clarify historical transactions.

The analytical synthesis used four related categories: spatial and hydraulic organization; ownership, leasing, and exchange; social and religious functions; and present heritage condition. Greater confidence was placed in claims supported by converging documentary, oral, and spatial evidence. Single-source claims were retained only when their origin and uncertainty could be stated clearly. This procedure prevented numerical estimates or remembered locations from being presented as established facts.

Documentary, oral, and spatial evidence were finally compared to reconstruct the mills' geographical, economic, social, and cultural roles while retaining uncertainty where evidence remained incomplete.

Results and Discussion

The combined evidence identified seven historical watermills and showed that their distribution followed the physical logic of the qanat system. They occupied positions where local relief could generate the hydraulic head required to turn the mechanism while remaining close to orchards, routes, and residential areas. The survey recorded an elevation of about 2,086 metres at the qanat emergence point. Over the first 864 metres toward the upper mills, the channel lost only 19.5 metres, an average gradient of roughly 2.5 percent. Much of this section followed the contours, preserving head and maintaining controlled flow. At the paired mills, however, the ground dropped about 20 metres over a horizontal distance of nearly 50 metres, creating a local slope of approximately 40 percent. Comparable localized breaks in slope occurred at other mill sites. Local builders thus conserved elevation along gentler sections and exploited steep drops where energy conversion was needed.

The mills formed an integrated qanat–orchard–settlement landscape. After powering a mill, water returned to the channel and continued toward gardens or another mill. Water from different qanats could also be combined before entering a pressure shaft. The Haji Molla Mohammad and Mir Seyed Ali mills stood close together and were remembered as paired mills; farther downstream, additional inflows contributed to the Mahalleh Qasem Mill. This sequence reflects practical knowledge of flow, elevation, channel alignment, cultivation, and settlement.

Documents reveal a structured property regime. Several mills were divided into 12 shares that could be inherited, leased, sold, or endowed. A lease dated 1335 AH assigned one share of the Sarbaghestan Mill for five years in return for 150 local man of wheat, or 30 man annually. This indicates the scale of rent attached to one share but cannot be generalized to every mill or year. A sale records one taq, treated as half a share, for 700 tomans in 1957. Assuming 12 equal shares, the transaction suggests a total value of about 16,800 tomans for the mill. This estimate demonstrates substantial capital value, although it rests on one transaction and assumptions about share equivalence.

Private property was also connected with collective and religious functions. Part of the income from mill shares was paid into a village development fund, although the amount and expenditure cannot be reconstructed. Endowment records show that shares supported the muezzin of the Jame Mosque in Derakhsh and iftar meals for fasting residents. Mills therefore linked household assets, production, public benefit, and religious obligation.

Interviews add an everyday dimension absent from formal records. Farmers and grain owners arrived from surrounding settlements and sometimes waited near a mill until their turn. Waiting created opportunities for communication and exchange of news. Milling provided direct work for millers and indirect activity for carriers, farmers, traders, and nearby businesses. The mills were thus social places as well as productive facilities.

Local estimates place combined flour production at about 1,850 kilograms per day. With 300 operating days after allowing for repairs or reduced flow, the implied annual quantity would be about 555,000 kilograms. These figures indicate scale rather than verified performance. No operational ledgers or reliable records of milling fees survive, and water availability and demand varied; consequently, the estimates were not used to calculate definite income.

Most mills declined during the 1960s as diesel and electric milling expanded, transport and agriculture changed, and residents migrated. The Haji Molla Mohammad Mill continued until about 1972–1973. After closure, channels and working spaces were no longer maintained, and later construction erased parts of the system. Three mills have now disappeared and four retain structural evidence. Their main present significance lies in their value as industrial-water heritage and evidence of local engineering, property relations, and collective memory.

Taken together, the findings show that technical, economic, and cultural functions were mutually reinforcing. The same location that made hydraulic operation possible also influenced access, waiting, trade, and the clustering of activity. The share system turned a physical structure into a divisible asset, while endowment practices redirected part of its value toward collective obligations. This combination distinguishes Sarkhong from accounts that describe watermills mainly in architectural or mechanical terms. It also explains why the disappearance of a mill represents more than the loss of a building: it removes a node from a wider network of water management, production, property, worship, mobility, and memory.

Oral testimony was strongest concerning names, owners, millers, and social practices, but less consistent when a structure had vanished. Comparing memories with the qanat route and elevation profile improved reconstruction without treating oral history as either infallible or dispensable. The Sarkhong case supports a relational approach to heritage: conserving only a chamber or wall would overlook the channel, elevation drop, orchard, access route, documents, and narratives that give it meaning. Nevertheless, the findings do not establish that restoration will necessarily reduce migration, create employment, or produce a successful tourist destination. These outcomes depend on structural stability, restoration costs, access, ownership, water rights, visitor capacity, local acceptance, and long-term management.

Conclusion

The Sarkhong watermills emerged from the relationship among topography, controlled qanat flow, vernacular engineering, and village organization. Their placement at abrupt elevation changes demonstrates that builders conserved hydraulic head along gentle sections and released it at selected points. Because discharged water continued toward orchards and downstream sites, the mills formed a connected water and settlement system rather than independent buildings.

Historical records establish that the mills were economically significant assets. Shares and taqs could be inherited, leased, sold, or endowed, while some benefits supported public and religious purposes. Oral histories show that the mills connected Sarkhong with neighboring settlements and created places of work, waiting, communication, and shared memory. Their contribution was therefore technical, productive, institutional, social, and cultural.

Their condition requires a cautious conservation strategy. Three mills have disappeared and partial remains survive at four sites. Priorities are measured and photographic documentation, condition assessment, recording of the associated qanat route, clarification of ownership and water rights, and emergency stabilization. Structural assessment should determine whether a better-preserved site is suitable for a pilot conservation project.

Interpretation should present the qanat, elevation profile, mill remains, orchards, documents, and oral histories as one landscape. A walking route or local exhibition should be considered only after technical, economic, and social feasibility has been established and residents and owners have participated in decisions. Intervention must preserve structural authenticity and the historical water route.

The study is limited to one village; several documents are incomplete, and some findings depend on memories recorded decades after closure. Triangulation reduced uncertainty, but conclusions should not be generalized to all qanat settlements without comparative research. Future work should combine architectural documentation, archaeological investigation, hydrological assessment, legal analysis, and community-based evaluation of reuse. Within these limits, Sarkhong demonstrates how geographical setting, economic relations, religious practices, and collective memory can be read together to understand and protect rural industrial-water heritage.