Acequias or irrigation ditches: an ancient knowledge making its comeback

“Acequias” (ditches) are one of the oldest existing systems of channeling and use of water. In the Iberian Peninsula we know them well: the first irrigation ditches are presumed to date from Roman times, but some authors speculate that they may be earlier. 

The concept might be older, but we inherited the word from the Arabic: الساقية “al-sāqiyah”, which has the meaning of “to carry water”, or “to give to drink”. It is at the time of Arab colonization that these structures find their maximum expansion on our soil. The structure itself dates back to the 7th century B.C., so it was well developed in other parts of the world (especially Mesopotamia) before the Arabs introduced it in Al-Andalus. 

An acequia is a channel or open ditch through which water flows. It can be dug directly into the ground, with the water flowing directly over it, or it can have a clay or clay lining that delays the absorption of the water. There are permanent ditches, which usually have this type of lining to prolong their useful life before needing repairs, and temporary ditches, which are opened specifically at certain times of the year, to drain land or irrigate seasonal crops, and which are usually directly made of earth, as they are not used again until the following year, and are covered in the months that remain unused. 

It is a sustainable and convenient way to control water flows, and although it has traditionally been used to irrigate fields or bring water to populations far from water sources, in today’s world it can find deeper and more significant applications. 

Beyond Mendoza: the acequia as a circulatory system

Perhaps the most famous case worldwide of how a network of irrigation ditches can dictate the character of a city is that of Mendoza, Argentina, a paradigmatic example of the power of urban irrigation ditches. When you zoom in on the satellite view of the city, you can easily see a strong green delineation in its street plan. Mendoza is a city full of trees that shouldn’t be able to thrive there: it is located in a semi-desert area with very irregular rainfall, which is occasionally torrential at specific times of the year, but very scarce the rest. 

Mendoza was a city rebuilt in the mid-19th century after an earthquake. Large urban trees were deliberately included in the design as a specific measure to improve environmental conditions, as Paula Lopez recounts in this El Pais profile of the Argentine city. The system of irrigation ditches makes it possible for these trees to survive, filling the streets with vegetation. 

However, the Mendoza municipality is not the only one that has seen its history crossed by the course of the irrigation ditches. We have a very important legacy of irrigation ditches much closer than we think: the millenary irrigation ditches of Al Andalus that are still preserved within our soil. 

Acequias of Al-Andalus: a perfect example of vernacular architecture

As archaeologist and UGR professor José María Martín Civantos explains, there is a whole system of millenary irrigation ditches that fell into oblivion with large scale agricultural practices. However, thanks to the archaeological excavations that are restoring the Andalusian ditches to its former glory, we discovered that, in addition to bringing water from the mountains to the crops, the acequias contribute to filling the aquifers, since part of the water from both rain and snowmelt infiltrates back into the subsoil, slowing and delaying by months its release into the rivers. For this reason, the rivers of the Sierra Nevada continue to carry water even in the dry season, when there is no more rain or snow in the mountains. 

Perhaps in this perfect example of vernacular architecture lies a key to better surviving future episodes of drought. It is one more instance in which the knowledge of native architectural structures holds possible solutions for the future, just as with structures such as the Mediterranean patio. 

Moreover, the concept of the acequia is not only applicable to large tracts of land: it can also be applied on a small scale in private gardens or patios. In addition to being a valuable bioclimatic architectural component, an acequia can be the aesthetic element that provides the backbone of an entire space, giving it elegance, fluidity and freshness.