MERIDA (Spain)

Roman aqueducts: Merida (Spain) Merida - COLONIA EMERITA AUGUSTA
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In the year 25 BC Emerita Augusta became a colony and a century later it had three major aqueducts two of which started with a dam in the upper parts of rivers.

Cornalvo aqueduct The Cornalvo aqueduct is the oldest and about 17km long. The aqueduct was originally built without the dam, and did not get its water from springs but was rather fed by a number of small branches that drained sediments of the Albarregas river. The dam was built later, around the time of the Proserpina dam described below, and it is not even certain which parts are roman and which parts may be later additions. The dam is 194m long, 20m high and on top 8m broad with a few flights of stairs at the water side. The Cornalvo dam is an earthern dam covered with masonry, and has a unique separate water inlet tower 10m from the dam at the inside. Just downstream from the dam is a side branche of the aqueduct, the Borbollón branch which also drains its water from an aquifer in sedements. A feeder aqueduct taps a small brook called Las Muellas N of Cornalco and brings additional water to the reservoir.
The water channel of the Cornalvo aqueduct runs mostly in tunnels, without major bridges and enters the town on the east side. A few remnants of the aqueduct are still visible in the town.

Las Tomas aqueduct(also known as Rabo de Buey)
The Proserpina aqueduct: the water was transported to Merida trough an aqeduct of 10 km long which entered the north side of the town by means of a aqueduct bridge over the river Rio Albarregas. The bridge has a maximum height of 30 meters. Its span is almost 4,5 m, the pillars are almost 3 x 3 m (10 roman feet = 2,96m). Because of its impressive appearance the bridge is called Los Milagros (the miracles).
The water of the second aqueduct, Las Tomas, comes from separate branches on the N and NE side of Merida. In order to cross the Rio Albarregas river there was a 1600 m long aqueduct bridge of which only three pillars of 16 m high each are left on the town side of the river next to the hippodrome. The large aqueduct to the N of these ruins is of younger date. In the 16th century most of the other pillars were used to construct a new aqueduct bridge, that of San Lazaro. Close to the Casa del Anfiteatro (House at the Amphitheater) the Las Thomas aqueduct runs on a wall, and a lion head of stone was found nearby which was in use as a gutter-spout.On the same spot there are remnants of a castellum aquae.

Proserpina aqueduct The Proserpina aquaduct is based at a dam which is located about 10 km north of Merida. It is the youngest of the three aqueducts of Merida and was build in the time of Traian at the beginning of the first century AD. A feeder aqueduct brings additional water into the reservoir of the dam, which collects the water from the Proserpina aqueduct. The dam is 427m long, 21,6m high and at the crest 2,3m wide. It is a earthen dam supported on the inside by a 6m thick retaining wall. This wall is built from a concrete core and granite masonry facing. The dam is built from three segments of slightly different orientation. On the inside nine buttresses support the retaining wall of the dam when the water is drained from the reservoir; without these buttresses, the retaining wall would collapse due to the pressure of the wet earth in the dam embarkment behind it. It has been suggested that is was the collapse of another similar dam, that of Alcantarilla for the aqueduct of Toledo, which brought the Roman engineers to build this safety feature into their design. On the outside, there are also buttresses, 16 in total, supporting the retaining wall, but these are covered by the earth embarkment and only known from drilling.
Two inlet towers are situated on the inside of the retaining wall. One contains two lead pipes of 22cm diametre placed three meters above the base of the dam, and the other inlet pipe higher up in the tower, where the water could be let out of the dam into the aqueduct. The water was transported to Merida trough an aqueduct 10km in length which entered the north side of the town by means of an aqueduct bridge over the river Rio Albarregas. The bridge has a maximum height of 30 meters with a span of nearly 4,5m. The pillars have dimensions of 3 x 3 m (10 roman feet = 2,96m). Because of its impressive appearance the bridge is called Los Milagros (the miracles). A number of storks nest on the tops of the ruined pillars of the Milagros aqueduct and make it more impressive still. The modest ruins of the castellum divisorium can be visited in a street some hundreds of metres south of the bridge; this is the end of the Proserpina aqueduct.

W.D. Schram


Item Cornalvo Las Tomas Proserpina
Length 17 km ? km 12 km
Cross-section x m x m x m
Volume ..000 m3/day ..000 m3/day ..000 m3/day
Gradient ..% ..% ..%
Period 1 century AD ?? century 2 century AD
  • roman dam
  • aqueduct bridge
  • roman dam
  • aqueduct bridge

Recommended literature : K. Grewe: Augusta Emerita / Mérida - eine Stadt römischer Technikgeschichte (Antike Welt (1993) p244)
Recommended website : Traianus site
How to visit : see maps and the descriptions at the individual aqueducts
HOME More literature on more aqueducts Last modified: March 25, 2005 - Wilke D. Schram (w.d.schram 'at'



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