Power Dams

Waterpower was a technology that did not really take off until after the 11th century. The invention of the dam was an essential development in the rise of waterpower because it diversified the applications of both the vertical and horizontal water wheels.


The Romans were the first civilization to harness the power of water however; they were limited to mostly grinding cereals. One of the most sophisticated dams built by the Romans was the Monte Novo dam located 15km east of Evora in southeast Portugal. It was a 5.7m high, 52m long arch dam with a radius of 19m and a central angle of 90°. The dam was built using blocks of shist laid horizontally in a lime mortar. the dam's reinforcement consisted of the fact that the curved central part at each end was embedded into the wing walls without any abutment blocks to absorb the horizontal arch thrust. The designers of this dam must have been unsure of their sophisticated design, because they also included two buttresses to increase the stability. It is thought that the water from two outlets was used to drive waterwheels further down the river, The outlets were 1.2m and 1.4m wide, with a height of 1m through the dam's base.

Medieval and Postmedieval Europe

It took several centuries for Europe to recover from impacts of Christian-ization and Germanization. By the end of the 8th century, about 300 years after the disintegration of the western half of the roman empire technology had gain sprouted new wings. Dams were built in order to remove the water-wheels from rivers where debris, ice jams and floods played havoc with the waterwheels and their structures.

One of the interesting dam built in this period for waterpower was the Castellar dam and millhouse in southwestern Spain. The dam's reservoir capacity is very small(0.3 milliom m3), however, the height of the dam was 19m high. This large height gave a very high potential head of the water in the reservoir, which could be transferred into waterwheel power. The millhouse was located at one end of the weir and supplied directly with water from the reservoir, a method of design that is used in modern low-head dam power plants. Another equally modern design characteristic was the location of the millhouse, which was near the toe of the 19m high reservoir. An equal number of vertical shafts lead the water to the horizontal water wheels. The sturdy end and intermediate walls of the mill house act as buttress because the width of the dam was only 36% of its height. Many of the concepts built into this dam have direct links to modern methods, although it was built around 1500 AD.

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