These hydraulic works are seven centuries old and are some 6 km northwest of the town of Guadalupe at an altitude of 915 metres on the southeast side of the sierra of La Villuerca. Easy access is afforded by the road from Guadalupe to Navalmoral de la Mata and then by a forest track starting at the Humilladero Chapel in a westerly direction, parallel to the route of the old water channel.
One of the most interesting cultural assets of Guadalupe was built by Hieronymite monks who made use of a hydrogeological resource. It consists of a system to collect, channel, and distribute drinking water by gravity to the monastery and the town of Guadalupe, which is known as the Arca del Agua. It dates from the year 1350 and is still in operation today, with only minor modifications having been made to the original structure.
The materials that make up the subsoil of the southeastern slope of the sierra of La Villuerca are layers of highly fractured quartzites, sandstones, and shales that are considered to be permeable or semi-permeable rocks. On these rocks lie the pedreras of Los Hollicios, which are made up of large angular fragments of quartzite that are highly permeable, with rainwater filtering in through the numerous gaps between these rocky blocks (the refill area). After passing through the pedreras the water percolates through the fractures of the subsoil materials and descends to great depths, being collected by means of underground collection galleries or water mines. On occasions the underground water comes out onto the surface unaided to create hillside springs locally known as bohonales or trampales, such as those occurring near the mines of the Arca del Agua. Some of these springs were also “captured” in order to supply the town of Guadalupe and its monastery.
These hydraulic works consist of the following parts:
Main collection: A network of drainage galleries or “water mines” that have been excavated in the southeastern slope of La Villuerca in search of the springs or “manaeros” that originate in the fractures of the quartzites and shales. The galleries are lined with ceramic bricks held together by lime mortar.
Storage: The “mines” concentrate the water in a pointed barrel vault cistern of granitic stones which is known as the Arca del Agua. It has a square ground plan of 5.3 x 4.0 m and is covered with a filling to stabilise the structure. Part of the Arca del Agua is above ground but the part occupied by the water has been excavated below ground.
Treatment: By pouring off the water collected in the Arca del Agua and in the adjacent small cistern.
Channelling: By means of tongue and groove ceramic pipes that have masonry “vents” every few metres; they eliminate air from the pipe and regulate the water pressure as far as the town of Guadalupe after it has crossed the hill known as the “Cerro Huraqueado” (“horadado” = perforated) by means of a inner gallery excavated for the purpose.