Polski
Science, Issue 5/2026
Ecohydrology without borders – how UNESCO is building intergovernmental cooperation around water
May
The year 2026 is full of ecohydrological anniversaries. Among other things, we are celebrating the twentieth anniversary of the UNESCO Ecohydrological Demonstration Areas and the thirtieth anniversary of the development of ecohydrology within the framework of the UNESCO Intergovernmental Hydrological Programme (IHP). Among the authors of the concept of ecohydrology, the world leader is Professor Maciej Zalewski – founder of the UNESCO Chair of Ecohydrology and Applied Ecology at the University of Lodz and the European Regional Ecohydrology Center of the Polish Academy of Sciences. He defined ecohydrology as a science that studies the functional relationships between hydrological processes and biotic factors at the catchment scale and uses this knowledge to build systemic solutions at the catchment scale (Zalewski et al. 1997; Zalewski et al. 2021). The concept of increasing ecosystem resilience and improving the quality of water resources is crucial.
Ecohydrology was formally introduced into the IHP program through the UNESCO document Ecohydrology : A New Paradigm for the Sustainable Use of Aquatic Resources (Zalewski et al. 1997). The development of this concept led to the creation of a network of UNESCO Ecohydrology Demonstration Sites (UNESCO Ecohydrology Demonstration Sites) – selected river catchments around the world where scientists, local governments and practitioners jointly test ecohydrological assumptions and, based on the results, implement Nature-based Solutions (NBS) elsewhere. These areas act as living laboratories, integrating scientific research with water management practice and enabling the exchange of experiences between countries (UNESCO, 2006).
Pilica – the beginning of an international network of demosites
The Pilica River catchment is one of the world’s first ecohydrology demonstration areas – the first of ten projects launched under the IHP program. The area faces problems typical of agriculturally used catchments, such as diffuse pollution runoff and water eutrophication. After diagnosing the challenges, a number of innovative nature-based solutions were developed and implemented there, including sedimentation-biofiltration systems, highly effective ecotone zones and denitrification barriers. These solutions reduce the inflow of nutrient pollution and promote natural water purification, while providing a model for other areas (Izydorczyk et al. 2015).
Cooperation between scientists, local governments, farmers and water management institutions plays a key role here. An example of such efforts is the LIFE Pilica project, coordinated by the European Regional Center for Ecohydrology of the Polish Academy of Sciences under the auspices of UNESCO in Lodz. The initiative combines scientific research with environmental management practices and involves local communities in water conservation (1).
Polish cities as laboratories for climate adaptation
Examples of urban demonstration areas include Radom and Lodz, where adaptation projects have been implemented. The LIFE RadomKlima project focused on adapting the city to climate change through sustainable water management. Among other things, the Sequential Sedimentation and Biofiltration System (SSBS) was implemented there, the Mleczna River was renaturalized, and a floodplain polder was built on the Cerekwianka River. The renaturalization of the Milk River made it possible to restore the natural meandering of the river along a 400-600m stretch, increasing retention and restoring the ecological corridor. In turn, the reconstruction of the Borki reservoir and colluvial ponds increased their retention capacity and resistance to eutrophication (2, 3).
Rain gardens, retention basins, green bus stops, permeable surfaces and solutions such as ClimaPond, ClimaBox and TreeTrench have also been created in compact urban areas. These elements not only improve water management, but also perform educational functions and integrate residents.
The Lodz demosite is primarily associated with the Sokolówka and Bzura river basins. Both rivers were heavily transformed and burdened with numerous stormwater drainage outlets, leading to disruption of the hydrological regime and ecosystem degradation. Implementation of the SSSB stormwater pretreatment system reduced phosphorus and nitrogen concentrations by about 60 percent (Zalewski et al. 2012; Szklarek et al. 2018; Jurczak et al., 2018). The experience gained at Sokolówka allowed the development of the Blue-Green Network Concept for the entire city of Lodz, promoting good rainwater management practices (Krauze et al., 2010; Wagner, 2020).
Malaysia – smart wetlands for the city of the future
Putrajaya Lake and Wetlands in Malaysia is one of the most comprehensive examples of implementing ecohydrology in an urban setting. The system includes a lake of about 400 hectares and about 200 hectares of wetlands, designed as part of an infrastructure to treat rainwater and surface water runoff from an urbanized and agricultural catchment area (4).
The wetland system was designed as a system of 24 interconnected cells (i.e., separate wetland areas), allowing for the gradual reduction of pollutant loads before the water is fed into the lake. In addition to improving water quality, it also serves a retention function, reducing the risk of flooding, and a recreational function, fitting into the city’s landscape. The engineering solutions used, such as the sill system and variation in depth and vegetation, allow optimization of conditions for sedimentation, sorption and biochemical transformation (5).
The efficiency of the system’s operation was confirmed in studies conducted on selected wetland cell tracts. Analyses showed high efficiency of nutrient removal. The reduction of total nitrogen (TN) averaged 82.11 percent, nitrate nitrogen (N-NO₃-) 70.73 percent, and phosphate (PO₄³-) 84.32 percent. The values obtained indicate that the system is highly effective in reducing eutrophication of lake waters (Sim et al. 2008).
A key role is played by aquatic vegetation that supports nutrient uptake and the growth of microorganisms responsible for biogeochemical transformations. The whole is supported by the Integrated Environmental Monitoring System (IEMS), which allows for ongoing analysis of water quality, hydrological and meteorological parameters. Putrajaya is an example of combining nature-based solutions with modern management and institutional cooperation.
Ecuador – a combination of tradition and modern hydrogeology
The UNESCO network currently includes three demonstration areas in Ecuador: Paltas Catacocha (2018) (Albarracín et al. 2021), Pelican Bay in the Galápagos (2019) and the Manglaralto River-Aquifer system established in 2025 (Jaya-Montalvo et al. 2025; Sánchez-Zambrano et al. 2026).
One of the most interesting solutions are special dams(tapes) that retain rainwater and seasonal flows of the Manglaralto River. The water infiltrates into the ground, feeding the aquifer, which is then used by the local community during periods of drought. The system is managed by JAAPMAN, the organization responsible for the treatment and distribution of water resources.
The solution supports drought adaptation and reduces groundwater salinization by creating a natural barrier to ocean water. At the same time, these measures stabilize the riverbed and reduce the risk of landslides. The Paltas-Catacocha region also uses traditional haying and water harvesting methods, which have helped restore local traditions and increase biodiversity by reducing the dominance of gray infrastructure.
Cooperation starts with the youth
UNESCO has for years emphasized the role of young people as co-creators of actions for the future. The UNESCO Youth initiative is based on the principle of with young people , by young people and for young people, involving the active participation of young people in the development and implementation of projects on issues such as climate change and water conservation (6).
Of particular importance is the UNESCO Ecohydrology Youth Network, a global network of more than 500 young people interested in water, ecosystems and sustainable development. It enables international cooperation, participation in research projects, educational events, and the development of competencies related to ecohydrology.
It is initiatives like these that show that effective water management requires not only modern technology and research, but above all cooperation between countries, institutions, communities and generations.
Authors: Konrad Budziński, Aleksandra Chamerska, Patrycja Chamczak, Michalina Kędzierska, Weronika Misztal, Kamil Osumek, Tomasz Ślusarczyk, Zuzanna Boruch, Paweł Jarosiewicz/ University of Łódź
pic. main: Sequential Sedimentation-Biofiltration System in the municipality of Przedbórz, realized by ERCE PAN (photo by Pawel Jarosiewicz)
Literature:
Albarracín M., Ramón G., González J., Iñiguez-Armijos C., Zakaluk T., Martos-Rosillo S. (2021). The ecohydrological approach in water sowing and harvesting systems: the case of the Paltas Catacocha Ecohydrology Demonstration Site, Ecuador. Ecohydrology & Hydrobiology, 21(3): 454-466. https://doi.org/10.1016/j.ecohyd.2021.07.007
Izydorczyk K., Michalska-Hejduk D., Frątczak W., Bednarek A., Łapińska M., Jarosiewicz P., Kosińska A., Zalewski M. (2015). Buffer zones and ecohydrological biotechnologies in reducing area pollution. European Regional Center for Ecohydrology of the Polish Academy of Sciences, ISBN 978-83-928245-1-0.
Jaya-Montalvo J., Soto-Navarrete L., Arteaga V., Mata-Perelló J., Carrión-Mero P. (2025) Assessment of the tourist carrying capacity in the Manglaralto River-Aquifer System, Santa Elena (Ecuador): a UNESCO Ecohydrology Demonstration Site. ICAIW 2025: Workshops at the 8th International Conference on Applied Informatics 2025, October 8-11,2025, Ben Guerir, Morocco.
Jurczak, T., Wagner, I., Kaczkowski, Z., Szklarek, S., & Zalewski, M. (2018). Hybrid system for the purification of street stormwater runoff supplying urban recreation reservoirs. Ecological Engineering, 110, 67-77.
Krauze K., Żelewski Ł., Włodarczyk R. 2010. The role of Urban Greenery in the City of the Future – The Blue-Green Network of Łódź. Acta Universitatis Lodziensis Folia Biologica et Oecologica, pp 5-21.
Sánchez-Zambrano E., Carrión-Mero P., Córdova-Pazmiño J., Sedamanos-Jumbo B., Medina-Toala I., Suarez-Zamora S., Morante-Carballo F. (2026). Stability analysis in the lower manglaralto river basin, Ecuador, with a focus on conservation of the UNESCO ecohydrology demonstration site. Frontiers in Earth Science, 14:1703090. https://doi.org/10.3389/feart.2026.1703090
Sim C., Yusoff M., Shutes B., Ho S., Mansor M. (2008). Nutrient removal in a pilot and full scale constructed wetland, Putrajaya city, Malaysia. Journal of Environmental Management, 88(2), 307-17. DOI: 10.1016/j.jenvman.2007.03.011
Szklarek S., Wagner I., Jurczak T., Zalewski M. 2018. Sequential Sedimentation-Biofiltration System for the purification of a small urban river (the Sokolowka, Lodz) supplied by stormwater. Journal of Environmental Management, 205, 201-208. https://doi.org/10.1016/j.jenvman.2017.09.066
UNESCO (2006) Demonstration projects on ecohydrology: integrative science to solve issues surrounding water, environment and people (https://unesdoc.unesco.org/ark:/48223/pf0000147490)
Wagner I., Breil P. (2013). The role of ecohydrology in creating more resilient cities. Ecohydrology and Hydrobiology. 13, 113-134. DOI: 10.1016/j.ecohyd.2013.06.002.
Wagner I. (2020). Urban ecohydrology or blue-green aspects of urban adaptation to climate change. Academia. Journal of the Polish Academy of Sciences. 2(62), 76-80.
Zalewski M., Janauer G., Jolánkai G. (1997) Ecohydrology: A New Paradigm for the Sustainable Use of Aquatic Resources UNESCO IHP Technical Documents in Hydrology No. 7.
Zalewski M., Wagner I., Frątczak W., Mankiewicz-Boczek J., Parniewki P. (2012). Blue-Green City for Compensating Global Climate Change. The Parliament Magazine, 350(791), 2-3.
Zalewski, M. (Ed.). (2019). Ecohydrology. PWN Scientific Publishers.
Websites:
- LIFE Pilica Project: https://lifepilica.pl/pl/
- RadomKlima project: https://www.life.radom.pl/pl/
- Demosite in Radom: http://ecohydrology-ihp.org/demosites/view/1901
- Demosite in Malaysia https://smart.putrajaya.my/project/putrajaya-lake-and-wetland/
https://iems.ppj.gov.my/ - Demosite in Ecuador: https://www.unesco.org/en/articles/manglaralto-new-unesco-ecohydrology-demonstration-site-ecuador
- UNESCO Youth: https://www.unesco.org/en/youth
