From the City to the Ecosystem: Biodiversity in Barcelona's Sustainable Drainage Systems
Sustainable Drainage Systems (SUDS) from applied research to a public policy challenge
Key principles:
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Source: Document: Barcelona SUDS STRATEGY- SUDS COMMISSION – BARCELONA CITY COUNCIL
Barcelona is a city that faces risks of flooding, due to insufficient drainage and possible overflows of the Besòs or Llobregat rivers. The city is subjected to the rainfall regime of the Mediterranean region characterized by high-intensity storms, and receives runoff water from the aquifer of the Serra de Collserola (SE slope), which, upon reaching the city, can cause flooding. To minimize the risk of flooding, good drainage is very important: in this case, it must be done artificially, since the urban surface is highly impermeable. The main purpose of SUDS is to help control water volumes and manage urban drainage in a more natural and economical way.
Guarantee water quality while protecting biodiversity for a bio-receptive city
SUDS minimize combined sewer and runoff overflows and improve groundwater quality. The SUDS act as a natural filter for potentially polluted water due to its passage through roads, which carry pollutants from road traffic, through urban parks and gardens, creating a healthier city.
These systems are built integrated into green spaces incorporating bio-receptive elements, such as the creation of habitats for flora, fauna and fungi, which also perform functions of pollutant retention, protection against erosion, and fixation of the soil among others. SUDS contribute to urban biodiversity and perform crucial functions for soil biodiversity.
The soil contains a quarter of the planet's biodiversity, is a critical element for a paradigm shift towards sustainable urban environments.
Paradigm change
Since 2005, Barcelona has implemented SUDS in several urban developments and remodeling projects of green spaces. Iconic spaces such as Parc Güell in Barcelona serve as an example of the integration of water management with urban planning. Understanding the behavior of water, recovering traditional techniques and reaching community agreements with citizens are key elements to manage the paradigm shift towards SUDS.
To ensure the effectiveness of SUDS, continuous monitoring and evaluations are carried out which are essential to analyze pollutant retention, infiltrated water quality, conduct permeability tests and biodiversity studies.
Biodiversity studies assess the positive effects of SUDS on soil and habitat diversity, providing valuable information for future urban planning. It is in these studies where researchers from the Biodiversity Research Institute (IRBio-UB) and the Faculty of Biology of the University of Barcelona come into play. The objectives are: to determine if these soils can retain pollutants, if they maintain good soil quality and health, to check their permeability and assess biodiversity.
Fungi and other soil inhabitants
Our researchers' investigation focuses on the creation and evaluation of SUDS technosols. These artificial soils are prepared with different sizes of mineral particles (gravel, sand, clay) and organic matter to achieve a biodiversity similar to natural soils. Professor Antonio Gómez Bolea explains that his work together with other IRBio researchers, Dr. Eduardo Mateo and Dr. Owen Wangsteen, concentrates on the biological part of soils, studying the specific wealth of bacteria, fungi and metazoa. They work through cultivation and with the technique of metabarcoding (technique based on PCR amplification of genetic markers present in a wide variety of species) to observe the existing soil biodiversity.
In addition, Dr. Gómez-Bolea underlines the importance of changing environmental awareness, emphasizing that transforming urban spaces with natural or pseudo-natural soils can improve the urban environment, cushioning the thermal amplitude, the “heat island” effect, and the management of Water. Although there are no definitive conclusions due to the recent implementation of these systems, Dr. Gómez Bolea hopes that over time changes in biodiversity can be observed and provide relevant data for the future of urban ecology.
Their work is vital to understanding how technosols can promote or limit biodiversity and ultimately contribute to improving urban sustainability
The importance of a balanced soil for fair permeability.
Dr. Núria Roca Pascual focuses her research on evaluations of the effectiveness of technosols as sustainable rainwater management systems.
| SOIL: Living, dynamic, organized and complex natural system, which is the result of: a) of physical, chemical and biological processes that allow microorganisms and plants to settle in a more or less weathered natural or anthropogenic origin material; b) mass and energy exchanges with its environment; c) An organization of the materials that leads to the differentiation of different layers or horizons. The latter are genetically related to each other due to processes of addition, loss, transfer and/or transformation, which have acted under the control of a set of formation factors (geological materials, climate, topography, living organisms and weather). Has aptitude to: a) Sustain terrestrial ecosystems by allowing the growth of plants and other organisms, to which it supplies nutrients, oxygen, water, and anchorage or, where appropriate, habitat; b) Develop a set of environmental functions and provide ecosystem services. |
Dr. Roca Pascual explains that urban soils are a group of soils that are formed in urban, industrial or mining areas. From original anthropogenic materials, technogenic substrates, they are usually in locations where the natural relief has been strongly modified by movements of lands, demolitions, contributions and filling. They are made up of artifacts of a very diverse nature: waste from human settlements, organic waste, debris, mining tailings, coal, slag, industrial ash, sewage sludge and dredging material. In the city of Barcelona, this reality is evident, since there are areas with an industrial history that present high values of heavy metals. Other areas may contain constructed geomembranes, which are very poorly permeable, or hard technical material (asphalt or construction materials).
Núria Roca Pascual also emphasizes that the soil is often a great unknown in popular scientific culture. While many people are familiar with air and water quality, few know in detail what lies beneath their feet. However, it is essential to understand the importance of soils in the urban context, especially in the development of sustainable cities.
| Superficial (0-10 cm): Depth 1 Subsurface (10-35 cm): Depth 2 Subsoil (>35 cm): Depth 3 |
From each sampled surface, the samples are mixed until they are homogenized and separated into two bags: one for the determination of soluble carbon and nitrogen and another to characterize the soils conventional soil parameters such as pH, carbonates, organic carbon, texture and cation exchange capacity in addition to analyzing the content of total, bioavailable and mobile metals. In addition, a probe is carried out to calculate the surface apparent density. With these tasks and with the study in general, Núria Roca is assisted by Iván Vázquez Cerro, a student of the degree of environmental sciences who is doing his final thesis and Santiago Espinoza, a doctoral student of the section of Plant Physiology.
Finally, the researcher insists on the fact that to fully understand how urban soils can contribute to sustainable cities, it is necessary to carry out more research on this vital element for subsistence, the soil.
In addition, the contamination of heavy metals in soils of historical industrial areas require a specialized approach in remediation techniques. These are techniques that are implemented with the aim of recovering the health of the soil, such as phytoremediation that uses plants and the microorganisms in the rhizosphere to absorb, accumulate, metabolize, volatilize or stabilize the pollutants, or the use of biochar which, due to its characteristics, decreases the mobility and bioavailability of the pollutants.
Building sustainable urban environments
This research is innovative in many aspects, and highlights the need to continue investing in changes that improve coexistence between the city and nature.
The studies of Dr. Núria Roca Pascual and Dr. Antonio Gómez Bolea in the framework of SUDS not only contribute to the understanding of urban soils, but also highlight the importance of soils in urban planning and the development of sustainable cities. With increasing urbanization, proper land management can contribute significantly to reducing environmental impacts and creating greener, healthier cities.
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Global Soil Biodiversity Atlas coordinated by the JRC and the Global Soil Biodiversity Initiative with more than 70 collaborating organizations and several hundred individual contributions. It illustrates the diversity of soil organisms, explains their geographical and temporal distribution, the functions of ecosystems and the services offered by soil biota. It also wants to draw attention to the myriad threats to soil biodiversity and propose solutions to conserve soil biodiversity through the development of policies aimed directly or indirectly at soil health, leading to more sustainable
To learn more about SUDS and water management: Sponge cities: how to make the most of rainwater to fight drought