Managing forests to improve water supplies
Sediments and pathogenic microbes must be removed from raw water to make it safe for human consumption, but disinfection with chlorine leads to the formation of by-products which are harmful to health. Dr Nahia Gartzia-Bengoetxea and her colleagues in the LIFE URBASO project are developing a forest-based solution to naturally reduce the need for water to be treated.
The water that comes out of our taps has been treated and purified beforehand to ensure it is safe for human consumption. Typically sediments are removed first with flocculants and coagulants and disinfected after with chlorine. However, treating water with chlorine itself leads to the formation of disinfection byproducts which represent a threat to human health. “Chlorine reacts with the natural organic matter in raw water and produces disinfection by-products like trihalomethanes, potentially carcinogenic substances,” explains Dr Nahia GartziaBengoetxea, a researcher at the NEIKERBasque Institute for Agricultural Research and Development. The amount and quality of natural organic matter in raw water varies according to the environment from which it is abstracted, and Dr GartziaBengoetxea says effective management of the surrounding land might improve the quality of water and so reduce the need to purify it. “We know that managing the area around water abstraction points affects the quantity and quality of the raw water in the abstraction point. This could then have some impact on the treatment that we
have to apply on the water, and ultimately on human health,” she outlines.
This is a topic Dr Gartzia-Bengoetxea is exploring in the EU-backed LIFE URBASO project, in which she and her colleagues are investigating the impact of the continuous cover forestry approach on both water quality and quantity in the surrounding area. The project team are working in the vicinity of Urdaibai Biosphere Reserve in the Basque country, a region in northern Spain that is heavily covered by planted forests. “Most of the surface water abstraction points in the Urdaibai reserve are located in planted forest areas mainly pine and eucalyptus plantations,” says Dr GartziaBengoetxea. These planted forests are typically managed using clearcut forestry practices, which Dr Gartzia-Bengoetxea says leads to an increased risk of soil erosion, which in turn has adverse effects on water quality. “Eucalyptus and pine trees are planted at the same time, then they are all cut together and the cycle starts again. So everything is the same age and species, and all the trees are cut at the same point,” she explains. “This means there is high potential for soil erosion.”
Buffer zones
As part of her role in the project Dr GartziaBengoetxea is working to improve the quality of surface water at the abstraction points and so increase the amount of drinking water available, reducing pressure on existing resources. The proposal is to essentially establish four buffer zones around the abstraction points, aiming to protect water from pollution and reduce the need for it to be treated. “The first zone is the riparian buffer zone, which extends 25 metres each side of the river. Then, there are three circular buffers, the first of which extends from the abstraction point until around 100 metres away,” says Dr Gartzia-Bengoetxea. These zones will be managed and protected, with the aim of reducing the amount of sediment in water at the abstraction points, and modulating levels of natural organic matter. “In the zone closest to an abstraction point, we plan to establish native riparian forests to control sediment,” outlines Dr Gartzia-Bengoetxea. “In the second and third protection zones, further away from the abstraction points, we will adopt multifunctional forest management, with a focus on close-to-nature forestry. The primary ecosystem service in these areas is
potable water production, while also allowing the production of high-quality timber .”
This work is being conducted at three demonstration sites, with the LIFE URBASO team aiming to transform the existing pine and eucalyptus plantations into native, continuous cover forestry silviculture. The impact of these measures on both water quality and quantity will be assessed in the project. “We are measuring the quantity of the water resource, the suspended solids in the water, the natural organic matter, while we are also measuring levels of ptaquiloside (PTA), a natural toxin produced by bracken ferns. Bracken fern is very common in forests and there is some evidence that PTA might have carcinogenic effects in humans,” continues Dr Gartzia-Bengoetxea. The wider effects of this forest transformation, beyond its impact on water quality and quantity, will also be monitored. “We will look at the impact on bird biodiversity, forest structure and plant diversity,” says Dr Gartzia-Bengoetxea. “We
are also adding some deadwood to soil, to increase levels of soil organic carbon and improve climate resilience. We are monitoring the impact of this approach in the project.”
The project team are also working with local residents around the Urdaibai Reserve, as well as visitors, landowners and other stakeholders, who may have different interests. The idea is not to impose a vision, but rather consider different viewpoints, aiming to strike a sustainable balance between the social and economic value of forests. “Our
Water quality
This work is currently focused on the surroundings of Urdaibai Biosphere Reserve, yet water quality and availability is a major concern across many parts of the world, so the project team is also keen to share their findings with other areas facing similar challenges. A manual has been produced, providing guidance to other councils or local organisations who may want to adopt the approach followed in the project in their own area. “We’ve developed guidelines
“In the zone closest to a water abstraction point, we plan to establish native riparian forests to control sediment. In the second and third protection zones, further away from the abstraction points, we will adopt a continuous cover forestry approach.”
researchers ask people questions like; what do you think about forests? What would you be willing to pay to ensure reliable access to high-quality raw water?” outlines Dr GartziaBengoetxea. A number of in-depth interviews have been conducted along these lines and the responses are currently being analysed, which will open up new insights into the financial value that people attach to high-quality raw water. “The project is developing a scheme for an ecosystem services payment model in the project,” says Dr Gartzia-Bengoetxea.
to automatically delineate these buffer zones around water abstraction points in the Basque country,” outlines Dr GartziaBengoetxea. Other regions in northern Spain and Portugal could implement this kind of methodology, while the project’s work has also attracted wider attention. “We met with researchers from the James Hutton institute in Scotland last year, who were developing guidelines for the Scottish government on protecting drinking water supplies,” says Dr Gartzia-Bengoetxea.
The wider context here is growing concern around water scarcity, intensified by the projected impact of climate change. The Basque country has a wet climate, and while overall precipitation levels are expected to remain fairly high in future, Dr Gartzia-Bengoetxea says rainfall patterns within that are projected to change. “It is expected there will be more intense rainfall, and longer periods of drought,” she says. This will affect water availability, which underlines the importance of managing resources effectively; Dr Gartzia-Bengoetxea and her colleagues are currently working to assess the impact of their approach in this respect. “We want to see if we can transform these young eucalyptus and pine forests, into more irregular, autochotonous forests, and if more water is then available in the abstraction points. We are also measuring levels of dissolved organic carbon as a proxy for certain disinfection byproducts,” she outlines. “We are looking to achieve certain targets in terms of levels of dissolved organic carbon.”
This monitoring work is still ongoing, and is set to continue beyond the conclusion of the project in 2026. By that point, Dr Gartzia-Bengoetxea hopes to have a clearer picture of the impact of the
project’s work. “We will gather more data on observed changes, showing the impact on these demonstration sites, on water quantity and quality, and on biodiversity and climate resilience,” she says. This could then encourage other local authorities to look at how they manage forested areas, and Dr Gartzia-Bengoetxea says there is wider interest in the project’s work. “Many municipalities are looking into implementing the project’s proposals at their water abstraction points,” she continues.
URBASO
Forest Based Solutions for Surface Drinking Water Protection, Biodiversity, Bioeconomy and Climate Resilience
Project Objectives
LIFE URBASO is evaluating forest-based solutions for the protection of surface water resources used for human consumption and biodiversity, with the aim of enhancing climate resilience and supporting the bioeconomy. The project proposes four protection zones, each with specific forest management protocols designed to safeguard the quantity and quality of raw water from abstraction points intended for human consumption. The main objective is to protect water abstraction areas in line with Article 6 of the Water Framework Directive.
Project Funding
The LIFE URBASO project is co-funded by the European Union’s LIFE Environment and Resource Efficiency under Grant Agreement Number LIFE20 ENV/ES/000687 Acronym: LIFE URBASO.
Project Partners
• Basque Centre for Climate Change (BC3)
• Euskal Herriko Unibertsitatea • Bilbao Bizkaia Ur Partzuergoa • EFE https://lifeurbaso.com/en/participants/
Contact Details
Project Coordinator, Dr Nahia Gartzia-Bengoetxea NEIKER-Basque Institute for Agricultural Research and Development 812 Bizkaia Science and Technology Park 48160 Derio, Bizkaia, Spain T: +34 627 998873 E: ngartzia@neiker.eus W: https://lifeurbaso.com/en/project-actions/
Dr. Nahia Gartzia Bengoetxea is a researcher at NEIKER – the Basque Institute for Agricultural Research and Development. Her work focuses on forest soils and their interactions with forestry practices and the environment, aiming to ensure that soils continue to provide the multiple ecosystem services on which society depends. Her research aims to generate knowledge and practical tools to guide forest management toward sustainability and climate resilience.
