Runoff water, an ally against climate change

Sevilla (EFE) – The use of runoff water in cities affected by high temperatures is emerging as an element that can help cities adapt to climate change, according to the head of the Department of Projects and Works of Emasesa, Mario Cabello Obel.

Sustainable Urban Drainage Systems (SUDS)

Cabello Obel explained in an interview with EFE that for this purpose there are urban sustainable drainage systems (SUDS) for the collection of runoff water, in order to use the resource for irrigation of parks and gardens and “laminate” the peak flows in sewage networks.

These water drainage techniques are being applied in the LIFE Watercool project (LIFE18 CCA/ES/001122) for adaptation to climate change in the Avenida de la Cruz Roja in Seville – co-financed by the European Union – with the aim of using this natural resource and technology to combat the high temperatures recorded in the Andalusian capital for more than three months of the year.

According to the head of the Projects and Works Department of Empresa Metropolitana de Abastecimiento y Saneamiento de Aguas de Sevilla, S.A. (Emasesa), a partner in the LIFE Watercool project, it is necessary to look for alternatives to changing the sewerage networks in cities, because changing them all “is unfeasible and unsustainable from both the economic and environmental point of view”.

In addition, the works “generate a lot of waste and consume a lot of energy”, therefore, “we must look for other strategies and from Emasesa is betting on the SUDS, which are being applied in the LIFE Watercool project in Seville”.

The SUDS include a series of water management systems such as draining pavements, rain gardens, gutters, flowerbeds, tree surrounds and filtering drains, green roofs, vertical gardens, among others.

Capturing runoff water

According to Cabello Obel, SUDS have two objectives: the first is to capture runoff water to “laminate” the flow peaks so that the sewage networks have sufficient capacity to transport it to the water discharge points, and the second is to take advantage of the runoff to infiltrate it into the ground.

Thanks to SUDS, runoff water is returned to the subsoil because the use of pavement, which makes cities increasingly impermeable, means that the resource is always conveyed to the pipes of the sewerage network, then to the treatment plants and finally to the discharge point.

This whole process “entails water treatment costs and significant energy expenditure”, because the entire sewerage network has a pumping system, among other systems.

Cabello Obel explains that, specifically, in the LIFE Watercool project a combination of both objectives is intended: water collection and saving, because “on the one hand it is intended to collect all that runoff and infiltrate it, and, in those episodes where the infiltration capacity of the soil fails to absorb that water, laminate it and conduct it to the sewerage network, the ducts and from there to the discharge points.

According to the Emasesa technician, “undoubtedly, these flows are going to be greatly reduced” due to the water deficit caused by the climate crisis.

Sustainability and efficiency

From the point of view of sustainability and efficiency, the expert stresses, everything that is not driving the water to a treatment plant is a commitment to efficiency, because it is saving a lot of money and resources in the purification of this resource, because taking the water from the collection point to the treatment plant involves “a very important energy cost of pumping and the consumption of the treatment plant itself that needs to purify the water.

He stresses the importance of the SUDS, because once the runoff water enters the sewage pipe is already a “black water” and carries a complete purification process “as if it were the water of any home,” according to Cabello Obel, who adds that, however, if it manages to capture it directly in the pipe despite containing “a little dirt or contamination” can be treated at the site where it was captured to infiltrate and return it to the aquifers.

The technician of the Seville company explains that, in turn, these aquifers refill the water wells that are used for the irrigation network of vegetation in a city like Seville where there are many months with very high temperatures and where it is intended to maintain the green areas so that in turn help to retain the runoff water when it rains. Therefore, “the irrigation network must be maintained and the vegetation must be watered”.

Cabello Obel will participate tomorrow, Thursday, in the second online forum organized in the framework of the LIFE Watercool – Red Cross Project and in which Josefina Maestu, advisor to the Secretary of State for the Environment in the Ministry for Ecological Transition and Demographic Challenge, will also intervene. EFE

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the European Union/EASME is not responsible for any use that may be made of the information contained herein.
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About LIFE18 CCA/ES/001122