Skip to content

Asia-Pacific Network for Global Change Research

Asia-Pacific Network for Global Change Research

Read our Science Bulletin

Achievements, challenges, opportunities and the importance of regional collaboration: Perspective from an APN project on nature-based solutions for urban water treatment

The escalating challenges posed by water quality degradation due to rapid industrialisation, urban expansion, and the unyielding impacts of climate change have cast a shadow over regions worldwide. Particularly pronounced in developing nations, the need for innovative approaches becomes paramount. Among these solutions, Nature-Based Solutions (NbS) emerge as promising champions, capable of not only curbing urban water pollution but also cultivating co-benefits and fostering resilient and liveable cities. 

Across Asia, the canvas of experimentation has seen the inception of pilot projects carrying the potential of NbS in urban landscapes. Yet, their efficacy and far-reaching impacts often remain inadequately documented. The dimensions of sustainability, replication and scalability need further exploration to gather deeper comprehension.

In an attempt to explore and educate, the Asia Pacific Network for Global Change Research has granted funding for our ambitious two-year project (October 2021 to September 2023). Titled “Integrated Assessment of Nature-Based Water Treatment in Urban Areas,” the project explores the corridors of Sri Lanka, the Philippines, and Vietnam. Its premise delves into the intricacies of NbS integration, examining constructed wetlands (CWs), constructed floating wetlands (CFWs), and alternative approaches like green roofs (GRs). Within this exploration, the project identified that while maturation ponds showed promise, their extensive footprint drew limited stakeholder support. Thus, the role of green roofs was adopted as an alternative avenue.

The project aimed at the following goals:

  1. Framework development: Crafting an assessment framework to holistically evaluate the effectiveness and impacts of chosen NbS for water treatment.
  2. Guides for success: Forging comprehensive guides encompassing technical, socio-economic, and policy aspects of NbS implementation.
  3. Trials of transformation: Conducting real-world trials of the formulated guides within diverse case studies to elevate their precision and applicability.

This concerted effort aims to catalyse the replication of successful NbS projects underpinned by well-structured information. The project unites a robust consortium, with the project proponent from Australia and ten partners from Sri Lanka, the Philippines and Vietnam, along with two international collaborators from Spain. This collaborative venture extended to include 36 additional participants, including educators, researchers, undergraduate and graduate students, chemists, engineers and administrators, synergising their expertise to fulfil the project’s aspirations.


Our project was carried out in a systematic way to produce the following:

  • Understanding the status and utilisation of NbS in all three participating countries

A comprehensive assessment of the present state of water quality in lakes and canals, wastewater treatment systems, water management, governance structures, and pertinent policies was diligently undertaken. The purpose behind this rigorous evaluation was to examine the existing landscape and utilisation of NbS for water and wastewater treatment across the triad of countries. These reviews add to the existing knowledge and have been disseminated in the form of insightful book chapters (Dang et al. 2022; Pachova et al. 2022; Velasco et al. 2022; Weragoda et al. 2022).

  • Mapping NbS in all three countries 

NbS mapping was carried out to disseminate information on existing NbS for water treatment and management in all three countries (; The generation of these web-based and GIS maps aims not merely at encapsulating knowledge within geographic markers, but envisions an expansive horizon where the public can engage, contribute and expand these maps by adding both existing and new NbS projects in other countries.

  • Stakeholder participation to acquire social and economic implications of NbS  

Various stakeholder meetings were integral to achieving project goals. These included regular partner meetings, five quarterly gatherings with experts in focal areas, focal group sessions, two annual national meetings per country, and two regional meetings (Vietnam 2022, Philippines 2023). These meetings garnered a wealth of insights, shaping project direction effectively. Published as perspectives on our APN project webpage (Devanadera et al. 2023; Mowjood et al. 2023; Trang et al. 2023a), they contribute to realising project objectives. 

  • Developing a framework to assess the effectiveness and impacts of NbS

A comprehensive evaluation framework for NbS effectiveness and impacts has been developed, focusing on constructed wetlands, floating wetlands, and maturation ponds. This adaptable framework assesses NbS effectiveness, hinging on the achievement of objectives and problem resolution. Technical excellence and maintenance are essential for effectiveness, distinct from cost considerations. The framework zooms in on targeted water quality improvements, while broader environmental, social, and economic outcomes demand examination to capture NbS co-benefits, address undesirable effects, and provide sustainability evidence.

Contextual factors—institutional setup, governance, and policy—enrich the assessment. The project sought answers to the following: 

  1. Is a given NbS socially embraced across stakeholder spectra? 
  2. Can policies accommodate NbS implementation and adjustments?
Figure 1 visually captures the interplay between effectiveness, impacts and SDG contributions. A matrix aligns these concepts with objectives and issues to guide assessments (Table 1). This matrix is employed across three diverse nature-based systems. A paper by Jegatheesan et al. (2023a) elucidates study outcomes.
Table 1: Matrix for the development of an assessment framework (Jegatheesan et al., 2023a). Please see the full-size table here.


  • Developing guides to NbS

We have curated a manuscript titled “Water Treatment in Urban Environments: A Guide for Implementing and Scaling Nature-Based Solutions – South/Southeast Asian Examples.” This manuscript is earmarked for publication in the Applied Environmental Science and Engineering for a Sustainable Future series under Springer publisher (Jegatheesan et al. submitted 2023).

This comprehensive book encompasses: Mapping of current NbS in partner nations; Suitability mapping; Economic analysis; Social acceptability; Constructed wetlands guide; Green roofs guide; Floating Wetlands guides (Sri Lanka and Vietnam); Plant selection guide for floating wetlands; and, Upscaling and replication pathways.

On our APN project webpage, you will find succinct overviews of the guides for constructed wetlands, floating wetlands, and plant selection for both, alongside brochures and videos (Hemalal et al. 2023; Thanh et al. 2023; Trang et al. 2023b; Trang 2023c; Velasco et al. 2023). These resources serve as conduits to share project knowledge and facilitate NbS replication.

Figure 2 unveils a suitability evaluation framework—ideal for launching newly constructed wetlands or assessing existing ones as NbS in the Philippines. This versatile framework can be tailored for other NbS applications as well.
  • Feasibility of trialling the NbS considered in the project and actual trials

Project objectives include trialling NbS studies in varied ways. In Vietnam, partners implemented floating wetlands in Bung Xang Canal in Can Tho City for urban wastewater management, subsequently replicating the concept at an Agricultural Seed Center in Vinh Long Province. The canal adjacent to the seed centre receives fertilised water from rice fields, fostering floating wetlands nutrient uptake, and this successful trial has been operational for over two and half months. 

Similarly, green roof systems established at Ho Chi Minh City University found application in a household where septic tank effluent is channelled to the green roof system, and this trial has been operational for over two months.

In the Philippines, the Society for the Conservation of Philippine Wetlands (SCPW) proposed Constructed Wetlands (CW) for septage treatment at Panguil River Eco-Park in Pangil Laguna. This park spans 12.5 km and plays a vital role in local life, monitored by the Laguna Lake Development Authority. The CW framework developed will be piloted here. In July 2023, SCPW conducted capacity-building, educating about wetlands, NbS, CW, and even cultivating Effective Microorganisms (Bokashi) for CW and local community use. Social acceptability surveys and focus group discussions determined the community’s promising stance on CW for the park’s septage treatment. However, the need for an actual working CW would be highly relevant for the constituents to fully accept the system. In another location in Laguna, a Green Village at Calauan has a working CW for their septage treatment but would require rehabilitation. These two different sites would provide a great validation platform for the developed framework since one is new while the other one is retrofitted.

  • Development of questionnaires to evaluate social and economic implications

Partners in all three nations crafted questionnaires and held stakeholder interviews, accessible via our project website (Jegatheesan et al., 2023b). From participants at the Bung Xang Canal floating wetlands questionnaire session, insights informed a manuscript submitted to a journal (Trang et al., under review). Further, the survey forms from the Philippines (suitability mapping and socio-economic evaluation of CW) have been discussed in the book manuscript for the NbS guide.

  • Offshoots of the project

The project surpassed its goals and yielded these additional outcomes, accessible on our APN CRRP2021-06MY-Jegatheesan project webpage (Jegatheesan et al. 2023c):

  1. Numerous impactful undergraduate and postgraduate research topics were initiated, resulting in exceptional theses.
  2. The establishment of lake management committees in Sri Lanka is in progress.
  3. A NbS society has been established by Sri Lankan partners to raise awareness about NbS benefits.
  4. Inspiring students to undertake scientific projects as well as other scientists in replicating and applying the floating wetlands for water treatment/management.  

Challenges and Opportunities

The project faced certain challenges throughout its duration. Notably, when constructing the framework for evaluating NbS effectiveness and impacts, acquiring comprehensive data proved to be a significant hurdle. Gathering data on water quality, technical specifications, and details regarding the social and economic aspects of the case studies presented considerable difficulties. This underscores the importance of establishing systematic data collection, collation, and storage processes specifically tailored to NbS. Such systems are crucial for enabling in-depth analysis and facilitating successful replication efforts.

The project found many opportunities. It showcased diverse forms of NbS scaling. Project partner guidelines facilitated replication of NbS, like floating wetlands and green roofs at stakeholder locations in Vietnam and constructed wetlands in the Philippines—representing wide scaling. Deep scaling was evident in enhancing existing NbS, including biofilm carrier trials and plant tests in Sri Lanka, as well as green roof substrate improvements and the use of effective microorganisms and waste materials, such as rice hull ash and recycled concrete for CW in the Philippines. Scaling up involved the adoption of wetland construction guidelines by the local government in the Philippines. Scaling out comprised forming lake management committees and fostering stakeholder exchanges in Sri Lanka. Hence, the project has facilitated numerous opportunities to explore, refine, and establish exemplary approaches to various scaling methods.

The project also encouraged the team to envisage the role of emerging technologies such as artificial intelligence (AI), satellite technology, sensor technology and blockchain technology on the replication of NbS projects through the enhancement of a Monitoring, Reporting and Verification (MRV) process in various ways. AI can play a crucial role in NbS projects by analysing vast amounts of data and identifying valuable patterns and insights. These insights can help measure the impact of NbS projects on ecosystem services like carbon sequestration and biodiversity conservation. Additionally, AI can optimise the implementation of NbS projects by identifying the most suitable locations and vegetation types for maximum effectiveness. The use of satellite data enables real-time and continuous monitoring of NbS projects. This technology allows for accurate measurement and evaluation of the effectiveness of these projects. For example, satellites can track changes in vegetation cover, water availability, and other environmental indicators, providing valuable information for assessing the impact of NbS projects on climate change mitigation and ecosystem health. Advanced sensor technology, including the Internet of Things (IoT) and devices and remote sensing equipment, can be deployed in NbS projects to gather real-time data on various environmental parameters. This data helps monitor and evaluate the progress of NbS interventions, such as air quality, soil moisture levels, and wildlife habitats. Such information supports evidence-based decision-making and enables project optimisation. Blockchain technology offers opportunities to enhance the MRV process in NbS projects through transparent and traceable data management. It ensures data integrity and security, particularly concerning carbon credits, land ownership and project outcomes. Blockchain-based systems can streamline verification processes, diminishing administrative burdens and facilitating efficient tracking of project results. Thus, these emerging technologies hold immense potential to enhance NbS projects and the MRV process. By providing accurate, real-time data, supporting decision making, increasing transparency and enabling efficient tracking and evaluation of project outcomes, they contribute to the advancement of sustainable practices.

Importance of Regional Collaboration

The project has cultivated a skilled community of diverse NbS experts poised to collaborate and share their insights, not only within the project countries but also globally. Partner collaboration fostered mutual learning, ensuring collective competence in evaluating NbS effectiveness, socio-economic assessment, installation and maintenance. While the construction of large-scale wetlands involves qualified contractors supervised by all three country teams, the shared expertise was pivotal.

Regional collaboration unveiled NbS implementation dynamics—differing accessibility and challenges. Certain countries found uniting stakeholders more straightforward. For small-scale NbS like floating wetlands and green roofs, local willingness and proficiency can be harnessed for replication. These insights are invaluable and could only have been gained through collaborative efforts on a regional scale.

Lastly, the regional collaborations foster robust bonds among project partners, cultivating a sense of extended family that empowers us to achieve greater and more sustainable accomplishments in the future. This unity instils strength and confidence, propelling us towards thriving success. We extend our heartfelt gratitude to APN for affording us this remarkable opportunity to collaborate and generate valuable outcomes that will serve as a blueprint for implementing nature-based solutions in pursuit of a sustainable future.


The project achieved success in formulating a comprehensive framework for evaluating the effectiveness and impacts of NbS in water treatment. This framework, based on case studies of constructed wetlands, constructed floating wetlands and green roofs in the Philippines, Sri Lanka and Vietnam, enabled the development of guidelines encompassing suitability assessment, installation procedures and operational considerations for these NbS. The guidelines were further tested and refined through stakeholder engagement, paving the way for their replication at various sites. To further accelerate the replication of NbS for water treatment, leveraging the significant strides achieved in this APN project across the three countries, a strategic approach is recommended. This entails the establishment of knowledge hubs, fostering living labs and developing comprehensive toolkits. Augmenting these efforts with the provision of short courses and training sessions focused on NbS will further solidify the framework for successful replication.