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Interview with Sergio Martos Rosillo from the Geological and Mining Institute of Spain

The expert spoke about ancestral systems for water management in Latin America and its benefits for global challenges such as the climate emergency. In this way, UNESCOSOT launches its interactive podcast series in which it looks for disseminate science around sustainability.

Barcelona, February 8

On December 11, 2020, the UNESCO Chair on Sustainability launched the Call for Good Practices in Ancestral Hydrotechnologies for Climate Emergency. A project that looks for revalue the intangible cultural heritage of native peoples.

Within the framework of this event, we invited Sergio Martos Rosillo from the Geological and Mining Institute of Spain with whom we pursue to expand concepts related to Ancestral Ecotechnologies and highlight their work around the project "Planting and Harvesting Water in Protected Natural Areas".

What are the most representative characteristics of the ancestral systems for water management in Latin America?

The diversity of water management systems in Ibero-America is very ample, so its characteristics are also very ample, and, especially, in areas with arid and semi-arid conditions. There are millenary water management systems that allow rainwater to be collected from rooftops and stored in cisterns. Systems that capture and channel the scarce runoff water that occurs during storms over a large area and concentrate it in a smaller area where species are grown that require a greater demand for water than is found in natural conditions. There are many wet areas, generically referred to as wetlands, where human beings have been managing water since time immemorial. This is the case of many high Andean wetlands where the waters of the snowy mountains are derived in order to increase the pasture area of camelids through complex networks of channels excavated in the wetland and known as camellones.

When these wetlands are used for agriculture, numerous channels are built and the extracted earth is piled up between the channels, giving rise to raised fields, also known as Waru-waru, in Peru, Zenú channels, in Colombia, or Suka-kollus, in Bolivia.

There are also other equally complex systems that capture rainwater, streams and springs and infiltrate it into the subsoil, to temporarily store it in aquifers. This infiltrated (seeded) water is collected, that is to say it is harvested later, during dry periods. For your catchment are used wells, underground galleries, or it is taken directly from springs or rivers that feed on this process of ancestral recharge of aquifers. We have focused on the study of these last systems, known in South America, as Water Sowing and Harvesting systems.

As general characteristics, the use of local materials for its construction can be pointed out. That they are systems adaptable to changing conditions, with minimal energy requirements, given that most work with the force of gravity, that use the self-purifying power of the soil and associated ecosystems and that in addition to generating economic benefits increase biodiversity. They are systems that favour social cohesion, since they require the involvement of the collective, and that improve the living conditions of the population. They are systems that have been operating for more than a thousand years. They are, therefore, living examples of resilience, from which, from the field of science and management, we have much, much, to learn.

Photograph 1: Author, Diego Aranibar Esteban / Iniciativa Mas Agua.

Photograph 1. Description:

Maintenance of water infiltration channels in a high Andean wetland in the town of Turuna, Commune of Colchane, Region of Tarapacá (Chile). These great wetlands are maintained by the Aymara communities, increasing, through water infiltration channels, the extension of these pasture areas and the regulatory capacity of these systems, that slowly discharge the infiltrated water from snowmelt to maintain the flow of springs and rivers located downstream.

How do you value the knowledge about them at present and especially their possibility of being replicated in different contexts to address the climate emergency?

Research on these ancient water management techniques is in the beginning. Investigating these systems requires interdisciplinary and multidisciplinary work teams, that they must have experts in anthropology, archaeology, paleoclimatology, ecology, hydrogeology, hydrology, agronomy and forestry engineering, among others. Only in this way can you reach your comprehensive knowledge.

From the point of view of my specialty, hydrogeology, we can say that there is almost everything to do. Research is currently beginning on the water regulation capacity of the extensive high Andean wetlands and the Waru-Waru, where the water management carried out allows agriculture, cattle raising and aquifer recharge, in addition to providing important ecosystem services. The investigation of the Peruvian amunas and the irrigation ditches of Sierra Nevada, in the south of Spain, has confirmed the efficiency and millennial age of this system of joint use of surface and underground water and of recharge of mountain aquifers. The effect of regulating the flow of rivers where these channels are used has already been demonstrated in the few hydrological basins where it has been investigated. The infiltration qochas or albarradas, the Andean tapes and many other Sowing and Harvesting Water systems are beginning to be monitored to demonstrate their hydrological efficiency as water regulation systems.

Another crucial investigation, to which much more attention should be paid, is the effects of water regulation provided by traditional irrigation systems. Traditional irrigation systems irrigated by gravity are far from being inefficient, as we have been led to believe. Irrigation surpluses in these agricultural areas present good qua