Historical Development of Arch Dams. From Cut-Stone Arches to Modern Concrete Designs
By Hubert CHANSON and D.Patrick JAMES

Dam designs may be divided into three main types : gravity structures relying
on their weight for stability, arch structures using the abutment reaction
forces and buttress dams. The design of an arch dam relies on the abutment
reaction forces to resist the water pressure force and it requires advanced
engineering expertise. The writers demonstrate that the historical development
of arch dams took place in five stages: the Roman arch dams, the Mongol arch
dam, four arch dams in the early 19th century, the Australian concrete arch dams
and the modern arch dams of the early 20th century.

The first arch dam is probably the Roman dam at Glanum (Saint-Rémy-de-Provence, France), built during the first century BC to supply water to the Roman town. Recent studies indicated that the dam was a thin arch made of cut stones and the wall abutments were cut in the rock (AGUSTA-BOULAROT and PAILLET 1997). The site was well selected . The writers hypothesise that the arch dam design was introduced because the site was favourable to a masonry dam but nearby construction materials were scarce. Another unusual Roman dam was the Esparragalejo dam, near Merida (Spain). Built around the 1st century AD for irrigation purposes, the structure was a multiple-arch buttress dam, 5.6-m high and 2-m thick at base with circular arches.
The arch technique was applied by the Romans to sewers, aqueducts and bridges, although there is no evidence of scientific design rules, Professor C. O`CONNOR suggested that, for Roman bridges, the ratio of arch rib thickness to span was about 1/10 for spans less than 15-m and could be reduced down to 1/20 for greater spans (O`CONNOR 1993). Interestingly the ratio of dam wall thickness to arch curvature radius was between 1/10 and 1/7 at Glanum (i.e. close to Roman bridge dimensions).

[2] During the 13th century, the Mongols invaded and settled in Iran where they built several large dams. Around the 14th century, they built also a number of arch dams (GOBLOT 1967). The Mongol arch dams were thick arch walls significantly higher than the Roman dams. The first one (Kebar, AD 1300) was heightened to 26 m around AD 1600 while the Kurit dam was 60-m high before heightening. Interestingly these structures were used for several centuries and several dams were still standing in the 1970s.
Some transfer of expertise on arch dam design might have taken place from the Romans to the Iranians. After the defeat of Valerian`s army in AD 260, 70,000 men were captured and transported to Persia where they were forced to work. The Roman prisoners built bridge-weirs and dams in Iran and some structures were still in use when the Mongols invaded in Iran. As the Roman army was involved in dam construction, the Mongols might be aware of the Roman arch dams. Both the Roman and Mongol dams in Iran were milestones in arch dam development. From the 14th century up to the beginning of the 19th century, the arch dam development was scattered and disparate.

[3] During the first part of the 19th century, the arch dam design was dominated by four large structures: the Meer Allum (India), Jones Falls (Canada), Zola (France) and Parramatta (Australia) dams. In India, the extra-ordinary Meer Allum (Mir Alam) dam was completed around 1804 with a 10-Mm3 water storage capacity. The multiple-arch dam was built to supply water to Hyderabad and it is still in use. It consists of 21 semi-circular vertical arches with span ranging from 21.3 to 44.8 m. The Jones Falls dam was completed in 1831 as part of the Rideau waterway system (Canada). The 18.7-m high dam was a constant-radius arch wall, 8.4-m thick at base. The dam is still used today for hydropower and navigation purposes. The Zola dam, was built between 1847 and 1854 for the water supply of Aix-en-Provence, France. It was the first arch dam design based on a rational stress analysis (SCHNITTER 1994). The reservoir was used as a town water supply until 1877. Today it is still in use for flood retention . The 12.5-m high Parramatta dam near Sydney (Australia) wa built between 1851 and 1856. It was a constant-radius arch with a cylinder shape and it was heightened by 3.35-m in 1898.
All four structures were constant-radius arches built in cut-stone masonry. They are still in use and their long-lasting operation demonstrates the soundness of design and the quality of the masonry construction. It is generally believed that the thickness of cylindrical arch was calculated using the thin cylinder formula. It is worth noting that three dams were built in the British empire. Two structures were designed by Royal Engineers : the Meer Allum and Jones Falls dams. The writers believe that the Royal Engineers in India were aware of the successes of Meer Allum and Jones Falls dams and they might have advised Australian engineers.

[4] The 75 Miles dam was built in 1880 near Warwick (QLD, Australia), as a water supply for steam locomotives (CHANSON 1999). It was a non-reinforced concrete thick arch. In 1900-1901, the dam was heightened with the addition of three concrete buttresses. The 75-Miles dam in 1880 is the world`s oldest concrete arch dam and it is still in use as an emergency reserve. Completed in 1896, Lithgow No. 1 dam (NSW, Australia) was a concrete single-radius thin-arch structure. In 1914 or 1915, the dam was heightened. The dam was disused around 1983-84 because the reservoir did not have enough available head to feed the new wastewater treatment plant. Lithgow No. 1 dam was the first Australian thin-arch dam, and it is the world`s oldest concrete thin-arch structure (CHANSON and JAMES 1998). Two thin-arch dams, de Burgh dam and Barren Jack City dam (NSW, Australia), were built around 1907-1909 for railway water supply. These were reinforced-concrete single-radius thin-arches, the world`s oldest reinforced-concrete thin arch dams. Another Australian arch dam is the Junction Reefs dam completed in 1897. The multiple-arch dam has 5 elliptical arches, each with a 8.5-m span and a 60-degrees lean. It was the first modern multiple-arch design.

[5] The introduction of concrete as a construction material for arch dams marked a significant advance. Designers were able to consider complex curved shapes to minimise the construction material and the overall cost. The developments took place first in North America. The world`s oldest cupola dam is the Ithaca dam (New York, USA, 1903). Designed to be a 27-m high structure, construction was stopped when the dam height reached 9-m because of local opposition. The oldest concrete multiple arch dam was the Hume Lake dam (California, USA 1908) built in the Sierra Nevada Mountains in 114 days ! The 206-m long 18.6-m high structure consisted of 12 circular arches (15.24-m span) and concrete reinforcement included old logging cables (over 12 km) and railroad scrap iron. The first constant-angle arch dam was completed in 1914 : the Salmon Creek dam (Alaska). The arch radius ranged from 44.96-m at base to 100.9-m at crest. Another advanced design was the Coolidge dam (Globe Ariz., USA 1928), the first cupola-shaped multiple-arch structure.