DAMS

 

versión española

 

When the climate or geographical conditions didn’t guarantee a regular supply of water, the Roman engineers didn’t hesitate about building dams, i. e., big cisterns in the open air that, after being filled, allowed its emptiness and a regular supply through an aqueduct, although it happened sporadically.

The idea of a dam is very easy, but its execution brought too many problems to the engineers, because they had to adapt the work to the terrain, to calculate the water pressure, to regularize the channels of evacuation without water dragging down the overflow channels of the dams, etc.

Nevertheless, they could build dams all around the empire with extraordinary dimensions: in Emesa, (nowadays Homs in Syria) the dam built basically for agricultural necessities was 2.000 metres long and it had a capacity for 90.000.000 m3,

Thanks to the emperor Nero, three dams were built and became into lakes in the Lazio to supply water to his private residence in Rome, the Domus Aurea; one of them was 39 metres high.

 

 

 

In Hispania three big dams guaranteed a regular flow to the aqueducts of Toletum (now Toledo) and Emerita Augusta (now Mérida).  The two dams in Mérida are dated in the age of the emperor Trajan and they were 194 and 427 metres long respectively and they reached 15 and 12 metres high; the dam of Toledo is dated in the II century a. C. and it was 550 metres long and 14 metres high.  These dams were reinforced with mortar walls (opus caementicium) and with talus that supported the water pressure and the weight of the dam.

In Aragon the dam of Almonacid de la Cuba and the dam of Muel are preserved in very good conditions; also there are remains of other dams:  in Muniesa the dam called “Pared de los Moros” –“Moor’s Wall”-, in Moneva, in Abrisén, in Villafranca del Campo, in Peralta de Alcofea, in Almerge, maybe in Monforte de Moyuela and Villarroya de la Sierra and, finally, in Sádaba (where the modern dam of Valdelafuen seems to cover the Roman dam).

 

Roman dam of Almonacid de la Cuba

(Photo: Roberto Lérida Lafarga 19/11/2007)

See the Roman dam of Almonacid de la Cuba

 

 

 

The dam of Muniesa, dated in the II century a. C., dammed up the flow of a inflowing of the Aguasvivas river, the Farlán brook, with a capacity of 150.000 m3; it is a dam with polygonal plan to adapt to the natural limestone of the brook; it has 5 sections of the wall that reached 58,60 metres; it is wider in the central part, until 2,48 metres.  The sections preserved are 5 metres high in some parts.  Inside the dam is made with opus caementicium –strong mortar-; outside the faces are made with opus incertum –small ashlars of grey limestone, yellowish sandstone and conglomerates-.  Downstream, the face was recovered with small blocks of stone horizontally distributed and was protect by a terrace –as upstream-; the outlet of water was double through two towers (castella ad capita) close to the upstream face.  Downstream it is preserved a gallery that joined the dam and the aqueduct in different sections up to 5 metres.

 

 

 

Downstream the modern dam of Moneva, the remains of a Roman dam on a anticline on the middle course of the Aguasvivas river are located; strong foundations in opus caementicium are preserved; upstream the dam is protected with small blocks of limestone, sandstone rolling stones and irregular conglomerates in small size, but put in horizontal courses similar to the opus incertum; downstream these reinforced are lost, but remains of a specus –channel- dug out in the rock are preserved.

 

 

 

Other important example of the hydraulic works that the Romans left in the present Aragon is the dam of Muel, with angular plan and probably rectangular section; it is preserved the upstream face in opus quadratum, i. e., with big blocks of stone -0,60 metres high every one-; the face is 13 metres high and 32 metres long; nowadays the face is used as support for the hermitage of Nuestra Señora de la Fuente ; the dimensions of the preserved section show the big capacity of the dam, although at the present its gap is filled up.  Its use was eminently agricultural, regularizing the flow of the Huerva river (the ancient Orba) for a large terrain downstream.  It is dated in the I century a. C. and it was in use after the Muslim domination.  

 

Roman dam of Muel

(Photo: Roberto Lérida Lafarga 19/11/2007)

 

 

 

 

 

SOURCES:

- MALISSARD, Alain: Los romanos y el agua: La cultura del agua en la Roma antigua, Barcelona, 1996

- CONNOLLY, P. y DODGE, H., La Ciudad Antigua.  La vida en la Atenas y Roma clásicas, Madrid, 1998

- BELTRÁN LLORIS, Miguel: “El agua profana en la cuenca media del valle del Ebro:  AQUA DUCTA.  La captación del agua, presas, embalses, conducciones”, en AA. VV.: Aquaria: Agua, territorio y paisaje en Aragón, Zaragoza, 2006

- ORTIZ PALOMAR, M.ª Esperanza y PAZ PERALTA, Juan Ángel: “La vida corriente de las aguas en el Aragón romano.  Trabajos públicos y placeres privados”, en AA. VV.: Aquaria:  Agua, territorio y paisaje en Aragón, Zaragoza, 2006