Archaeologists have uncovered a network of medieval tunnels beneath Gan Ha-Shelosha National Park in northern Israel, just north of the West Bank. The site, located along Nahal ‘Amal waterway, was once part of a system that powered the sugar industry of the Mamluk Empire. Carved into soft tufa rock, the tunnels reveal how medieval engineers transformed brackish spring water into mechanical energy, adapting their methods to a dry landscape. Radiometric dating and archaeological evidence suggest these channels supplied water to sugar mills, linking local ingenuity to the wider economic currents of the late medieval Mediterranean.
The discovery was made by a multidisciplinary team led by Amos Frumkin of the Hebrew University of Jerusalem. It began when infrastructure work exposed five parallel openings. “Their engineering precision suggested a hydraulic purpose,” Frumkin explains. “But unlike the open aqueducts typical of the era, these channels were subterranean—an adaptation to the valley’s geology and the brackish nature of the local water.”
A Tunnel C. General view of meeting point between quarrying teams, looking west. Oil-lamp niche marked with red circle, horizontal deviation with green arrow, and vertical deviation with blue arrow (photo: Azriel Yechezkel); B Tunnel C, looking east toward the T junction (photo: Azriel Yechezkel). C Tunnel C, speleothems on tunnel roof. Location where stalactite samples were extracted shown with red circle (photo: Azriel Yechezkel). D: Entrance to Tunnel D (photo: Amos Frumkin)
Using Uranium–Thorium dating of stalactites formed soon after the tunnels’ excavation, the researchers determined that the structures were likely built in the late Mamluk period (15th–16th centuries CE). One sample yielded a date of 1497 ± 36 CE, confirming that the tunnels were active around the height of the Mamluk sugar industry. This period corresponded with the flourishing of sugarcane cultivation in the Bet She’an Valley, a region known for its fertile soils and numerous springs.
The ‘En ‘Amal spring, which feeds Nahal ‘Amal, produces a steady year-round flow of water—measured in the early twentieth century at nearly 2,500 cubic metres per hour. Although its high salinity (870–970 mg of chloride per litre) made it unsuitable for drinking or irrigation, it proved ideal for industrial use. The Mamluks took advantage of this stable water supply to power mills in a landscape otherwise limited by seasonal rainfall.
Historical sources describe the Mamluks’ expertise in water management—from aqueducts and baths to extensive irrigation networks—but this discovery shows how they also used water energy for industrial purposes. Sugarcane production required steady irrigation and mechanical crushing, processes traditionally powered by flowing water. The tunnels of Nahal ‘Amal likely drove horizontal paddle wheels that turned millstones to crush cane, converting the valley’s brackish spring water into mechanical power rather than irrigation.
A late Mamluk lamp (used until the sixteenth century CE) found at the eastern mill (Fig. 11), downstream of the tunnels (mill 2 in Fig. 2). A—top view; B—front view.
Frumkin and his team—Azriel Yechezkel, Dror Segal, and Yinon Shivtiel—found that the tunnels’ slope, flow traces, and location matched the requirements of sugar mills rather than flour mills. A Mamluk oil lamp recovered in a downstream mill further supports this dating. Archaeological surveys show that the sugar mills were later repurposed into flour mills during the Ottoman period, when vertical penstocks were added above the earlier chute-fed water systems.
The research team documented six main tunnels along Nahal ‘Amal. Five entrances on the north bank form an interconnected system, while a sixth, on the south side, differs in shape and elevation, possibly reflecting a separate or earlier use. The tunnels include niches for oil lamps carved into the walls, and traces of slow-moving water on the rock surfaces indicate long-term flow. Some sections may have functioned as overflow channels to relieve pressure when the mills were inactive.
Tunnels C–E. Plan, profiles, and cross sections
The researchers note that the tunnels’ design offered a practical solution to the steep stream banks and soft tufa cliffs of the area. Instead of constructing open aqueducts, which would have been difficult and prone to collapse, the Mamluks carved tunnels directly into the rock. This protected the watercourse, minimized evaporation, and kept the channels stable across seasons.
“This discovery bridges industrial archaeology and hydrology,” says Frumkin. “It demonstrates that medieval engineers in the southern Levant adapted not only to scarcity but also to opportunity—turning brackish water into a sustainable source of power.”
During the late medieval period, the Bet She’an Valley was one of the most important sugar-producing regions in the eastern Mediterranean. Contemporary Arabic and Christian sources describe the area’s extensive sugarcane fields and the export of refined sugar to markets across the Middle East. The study highlights how Mamluk rulers viewed water not only as a means of irrigation but as an economic resource—investing in infrastructure that supported lucrative industries such as sugar, textiles, and metalworking.
Tunnel F, Plan, profile and sections
The findings challenge assumptions that the arid Levant was technologically stagnant in the Middle Ages. Instead, they portray the Mamluks as pragmatic innovators whose infrastructure supported both local communities and international trade.
“Understanding these hidden tunnels helps us see the Mamluk world not just as a military empire,” Frumkin notes, “but as one deeply invested in harnessing natural forces for economic resilience.”
More details about the discovery can be found in the article, “Water tunnels at Nahal ‘Amal (Israel): evidence of a water-based sugar industry in the Mamluk period?,” by Amos Frumkin,
Azriel Yechezkel, Dror Segal and Yinon Shivtiel, which is published in Water History. Click here to read it.
Top Image: The northern bank of Nahal ‘Amal on the late 1960’s, looking east. Assumed inlets are indicated by red circles, diverting water into the tunnels system; the eastern mill is hidden by the hill, downstream of the tunnels (blue arrow). The hill was partly removed by construction works on 2017, revealing the inner parts of the tunnels. Photo by Azarya Alon
Archaeologists have uncovered a network of medieval tunnels beneath Gan Ha-Shelosha National Park in northern Israel, just north of the West Bank. The site, located along Nahal ‘Amal waterway, was once part of a system that powered the sugar industry of the Mamluk Empire. Carved into soft tufa rock, the tunnels reveal how medieval engineers transformed brackish spring water into mechanical energy, adapting their methods to a dry landscape. Radiometric dating and archaeological evidence suggest these channels supplied water to sugar mills, linking local ingenuity to the wider economic currents of the late medieval Mediterranean.
The discovery was made by a multidisciplinary team led by Amos Frumkin of the Hebrew University of Jerusalem. It began when infrastructure work exposed five parallel openings. “Their engineering precision suggested a hydraulic purpose,” Frumkin explains. “But unlike the open aqueducts typical of the era, these channels were subterranean—an adaptation to the valley’s geology and the brackish nature of the local water.”
Using Uranium–Thorium dating of stalactites formed soon after the tunnels’ excavation, the researchers determined that the structures were likely built in the late Mamluk period (15th–16th centuries CE). One sample yielded a date of 1497 ± 36 CE, confirming that the tunnels were active around the height of the Mamluk sugar industry. This period corresponded with the flourishing of sugarcane cultivation in the Bet She’an Valley, a region known for its fertile soils and numerous springs.
The ‘En ‘Amal spring, which feeds Nahal ‘Amal, produces a steady year-round flow of water—measured in the early twentieth century at nearly 2,500 cubic metres per hour. Although its high salinity (870–970 mg of chloride per litre) made it unsuitable for drinking or irrigation, it proved ideal for industrial use. The Mamluks took advantage of this stable water supply to power mills in a landscape otherwise limited by seasonal rainfall.
Historical sources describe the Mamluks’ expertise in water management—from aqueducts and baths to extensive irrigation networks—but this discovery shows how they also used water energy for industrial purposes. Sugarcane production required steady irrigation and mechanical crushing, processes traditionally powered by flowing water. The tunnels of Nahal ‘Amal likely drove horizontal paddle wheels that turned millstones to crush cane, converting the valley’s brackish spring water into mechanical power rather than irrigation.
Frumkin and his team—Azriel Yechezkel, Dror Segal, and Yinon Shivtiel—found that the tunnels’ slope, flow traces, and location matched the requirements of sugar mills rather than flour mills. A Mamluk oil lamp recovered in a downstream mill further supports this dating. Archaeological surveys show that the sugar mills were later repurposed into flour mills during the Ottoman period, when vertical penstocks were added above the earlier chute-fed water systems.
The research team documented six main tunnels along Nahal ‘Amal. Five entrances on the north bank form an interconnected system, while a sixth, on the south side, differs in shape and elevation, possibly reflecting a separate or earlier use. The tunnels include niches for oil lamps carved into the walls, and traces of slow-moving water on the rock surfaces indicate long-term flow. Some sections may have functioned as overflow channels to relieve pressure when the mills were inactive.
The researchers note that the tunnels’ design offered a practical solution to the steep stream banks and soft tufa cliffs of the area. Instead of constructing open aqueducts, which would have been difficult and prone to collapse, the Mamluks carved tunnels directly into the rock. This protected the watercourse, minimized evaporation, and kept the channels stable across seasons.
“This discovery bridges industrial archaeology and hydrology,” says Frumkin. “It demonstrates that medieval engineers in the southern Levant adapted not only to scarcity but also to opportunity—turning brackish water into a sustainable source of power.”
During the late medieval period, the Bet She’an Valley was one of the most important sugar-producing regions in the eastern Mediterranean. Contemporary Arabic and Christian sources describe the area’s extensive sugarcane fields and the export of refined sugar to markets across the Middle East. The study highlights how Mamluk rulers viewed water not only as a means of irrigation but as an economic resource—investing in infrastructure that supported lucrative industries such as sugar, textiles, and metalworking.
The findings challenge assumptions that the arid Levant was technologically stagnant in the Middle Ages. Instead, they portray the Mamluks as pragmatic innovators whose infrastructure supported both local communities and international trade.
“Understanding these hidden tunnels helps us see the Mamluk world not just as a military empire,” Frumkin notes, “but as one deeply invested in harnessing natural forces for economic resilience.”
More details about the discovery can be found in the article, “Water tunnels at Nahal ‘Amal (Israel): evidence of a water-based sugar industry in the Mamluk period?,” by Amos Frumkin,
Azriel Yechezkel, Dror Segal and Yinon Shivtiel, which is published in Water History. Click here to read it.
Top Image: The northern bank of Nahal ‘Amal on the late 1960’s, looking east. Assumed inlets are indicated by red circles, diverting water into the tunnels system; the eastern mill is hidden by the hill, downstream of the tunnels (blue arrow). The hill was partly removed by construction works on 2017, revealing the inner parts of the tunnels. Photo by Azarya Alon
Subscribe to Medievalverse
Related Posts