You undertook your bachelor’s degree in psychology, before moving on to a master’s degree in environmental science which is a vast field. What influenced your decision to shift your research focus to environmental science, particularly water management?

The science behind nature's beauty, as well as understanding how and why things happen in nature, has captivated me since childhood. Because I intended to pursue a career in medicine, I studied psychology, biology, and other related subjects. When I participated in the AmeriCorps national service program at the NYC Mayor's office-NYC Service, I was assigned to the environment cluster where I gained extensive experience and knowledge about urban forestry conservation, urban biodiversity, water management, and urban green programs through a variety of government and non-governmental organisations. Working with professionals in the forestry, environmental conservation, water management, urban agriculture, and urban planning sectors provided me with the opportunity to learn and serve diverse communities in New York. I found myself fascinated by the environmental field and amazed at how nature can be incorporated into such a busy and mega city as New York. On the other hand, the tropical rainforests of Sri Lanka, as well as the biodiversity of these ecosystems, and the integrated water management systems, such as the ancient water gardens at Sigiriya and cascade systems linked to large ancient reservoir systems in Sri Lanka, have always fascinated me. As a result, I decided to pursue graduate studies in Environmental Science at the City University of New York. Additionally, while working at the NYC Department of Environment Protection as a graduate intern in Wet Weather Planning and Water Quality Policy Analysis, I was involved in green infrastructure projects for stormwater management and water conservation, which led me to focus on water management, eco-hydrology, and urban stormwater. It has been a long journey for me to learn, explore, and grow in the field of environmental science.

You are currently working on a Ph.D. focusing on Nature-based Solutions (NbS) for climate change risk reduction and resilient cities. Can you briefly explain the capabilities of NbS in mitigating risks from hydro-meteorological hazards such as floods, droughts, landslides, etc.?  

Human activities alter the tipping point of natural equilibrium by increasing global temperatures, primarily through greenhouse gas emissions. This increased natural hazards, including hydro-meteorological hazards, result in significant damage to societies and properties. Hydro-meteorological hazards are natural aspects of the Earth's system, which are closely associated with the hydrological cycle and other earth cycles and processes. Consequently, human actions are crucial to reducing climate-induced disaster risks, as well as hydro-meteorological hazards, such as floods, droughts, and landslides. The Paris Agreement aims to keep the temperature rise below 2°C (3.6°F) pre-industrial levels, and preferably below 1.5°C (2.7°F). It is necessary to develop strategies and policies that will help cities achieve Net-Zero specifically.

Natural-based solutions (NbS) have the potential to reduce hydro-meteorological hazards in the long run by minimising the gaps associated with decarbonisation and reducing greenhouse gas emissions. NbS are actions to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges such as climate change impacts, human health, food and water security, and disaster risk thereby benefiting people and nature (IUCN, 2022). The techniques can be used to rehabilitate and conserve natural ecosystems, incorporated into modified and artificial ecosystems, and can be used to enhance natural processes that control and absorb weather-related shocks. Additionally, the carbon cycle, the water cycle, the sedimentary cycle, and other geobiological cycles are regulated. All aspects of ecosystem-based adaptation (EbA), ecosystem-based disaster risk reduction (Eco-DRR), ecosystem-based mitigation (EbM), and green infrastructure fall under the umbrella of NBS. The NbS include forest, mangrove, and wetlands ecosystem conservation, halting deforestation, increasing reforestation, climate-smart agriculture, and open green spaces. Several green infrastructure methods are available to promote resilient, net-zero, environmentally friendly, safer, and healthier urban areas. These include green roofs, urban forests, bioswales, and urban ecological corridors. 

World Bank (2022) estimates that approximately 37 percent of the mitigation necessary to meet the targets of the Paris Agreement by 2030 can be achieved through successful NbS. By regulating evapotranspiration, infiltration, filtration, and retention of rainwater, NbS can also absorb atmospheric greenhouse gases, mainly carbon dioxide, thus reducing global temperatures, which is a major contributing factor to extreme and frequent hydro-meteorological events associated with climate change. Therefore, implementing  that NbS in ecosystem conservation, restoration, and management efforts, supports water management (in terms of quality, quantity) contributes towards maintaining and/or enhancing biodiversity by providing habitats, breeding grounds, and roosting grounds for wildlife. By providing eco-services through the above-mentioned NbS, human well-being can be enhanced. It is also possible to embed NbS into gray infrastructure, where NbS are more sustainable and cost-effective. With co-benefits and cost-effectiveness considered, NbS can spread widely in the global north and south, reducing vulnerability and exposure to natural hazards, increasing adaptive capacity, and reducing the impact of natural hazards on countries, cities, and communities worldwide. 

Planning and procedures based on science and technology are crucial for mitigating the adverse effects of anthropogenic climate change on water issues. Managing the impacts of climate change is a significant obstacle to achieving the Sustainable Development Goals. Climate change impacts are not merely environmental but are also closely correlated with economic and social dynamics.

Do you plan to use space technology for your research and if so, how?

Yes, indeed! Space technology is an essential feature in the planning, implementation, and monitoring of NbS and beyond. Further, space technology today is so advanced that it can be used to capture and predict changes in water cycle components, such as evapotranspiration, precipitation, and soil-related data for infiltration, groundwater storage, etc. Remote sensing data and satellite-derived information hold a significant role in obtaining accurate data on a specific site anywhere on the Earth's surface. Space technology, through its ability to observe both temporal (present situation and years ago) and spatial (one location to another) changes, it provided me the tools and data to analyse cause and effect, plan and model, and make projections (mapping of watersheds and land use changes, plant species, flood levels, etc.) in the study area. Science-based analyses can lead to policy implementation that improves humankind and heals the world from the effects of climate change and water scarcity.

The most recent project you were involved in focused the use urban NbS (conservation of Ramsar-Colombo) to mitigate urban floods thus promoting adaptation to climate change. Can you expand on the application of space-based technologies and/or data in this project and what were the project outcomes? 

The Colombo wetlands are accredited as a Ramsar site, located at the capital city of Sri Lanka, within the Kelani River delta. It receives approximately 2400mm of rain annually and more than 400mm per month in the monsoon season and inter-monsoon season. This lowland area is highly susceptible to flooding, including flooding caused by rivers, fluvial flows, flash floods, and urban stormwater. Water retention and flood reduction are  some of the eco-services provided by wetlands. However, on account of rapid urbanisation and infrastructure development, wetlands in the capital are deteriorating and disappearing. The degraded watersheds, declining wetlands, and increase in impervious surfaces, erosion and sedimentation, and encroachment on riverbank reservations; all have resulted in increased flood risk and vulnerability. 

In this project, space-based data were used to analyse temporal and spatial changes within the study area, particularly vegetation cover changes. The Normalised Differentiated Vegetation Index (NDVI) was applied to evaluate land use and land cover changes. Temporal changes was verified with Google Earth Pro. During the past two decades, Colombo wetlands have declined significantly, and the wetland complex has been converted to different land uses due to infrastructure development. In addition to degraded watersheds and diminished wetlands, there has been an increase in impervious surfaces, and encroachment on riverbanks. During the present climate crisis, it is critical to conserve and restore the Colombo wetlands and other wetlands throughout the world, and space technologies and data can help a great deal.

What are the challenges inherent in the applying satellite remote sensing and GIS techniques to national wetland inventories? How can they be overcome?

Wetlands are highly valuable for mitigating floods and provide a wide range of ecosystem services and goods. It is critically important to collect data about wetland ecosystems, but the task can be challenging. National wetland inventories require accurate, timely, and reliable data on the status of wetlands. Wetlands are highly dynamic ecosystems that include different vegetation types, water movement, and land cover. The surface area of wetlands expands and contracts as the water level changes, storing significant amounts of water. In wetlands, soil moisture, surface water extent, etc., can fluctuate widely depending on seasonal changes (rainy and dry seasons), sometimes even throughout the day. 

Wetlands are usually characterised by constant water at or near the land surface, either above or below it, depending on their energy signature. Water flow into and out of wetlands is controlled by the temporal and spatial variability of energy and gravity, which allow water to move from high to low energy zones. We need data for both the wet and dry seasons. Sometimes satellite data cannot capture accurate water levels/presence of water, or satellite data may not be available.  

When conducting research in the global south, accessing data is a significant problem. Conducting a national wetland inventory requires many technical and technological facilities, skilled professionals, effective government and institutional research engagement, and financial support. Developing countries face a major challenge in acquiring high-resolution data relevant specifically to their regions. Often, stakeholders involved in the wetland inventory process, including government officers, cannot access data frequently enough to capture the problem in real time. Even though there is extensive spatial coverage worldwide (Landsat, Copernicus, etc.), coverage of specific areas within the wetland is another challenge as a limited number of satellite data is available, and clouds often cover images. In addition, data are sometimes low-resolution, making it challenging to identify the types and species of wetland flora, such as the types of mangrove species within a wetland site. The lack of historical data to compare the present situation is another challenge. Sometimes, data is not accessible to individual researchers, and the cost of the most up-to-date data and software to analyse the information is high. Access to high-resolution space-based data in free and open-source platforms and affordable software for space-based data analysis are among the options to overcome some of the challenges mentioned above.

In your opinion, how is the open and free data policy of the European Copernicus Programme supporting wetland practitioners and other stakeholders to routinely integrate Earth Observation in their work to better fulfil their commitments and obligations towards the Ramsar Convention on Wetlands?

The open and free data policy of the European Copernicus Programme offers invaluable support to wetland practitioners and other stakeholders to conduct wetland inventory-related data collection efficiently, cost-effectively, and in a timely manner. It is necessary to monitor wetlands and ensure that their conservation status is documented periodically. With free access to space-based data, wetland practitioners and stakeholders can fulfil their commitments to sustainable wetland conservation by providing adequate seasonal (wet/dry) data. Reducing data costs minimises financial strains and burdens on stakeholders who monitor wetlands for conservation.

What are the promising new space technologies and multi-sensor approaches for more accurate and consistent detection of wetlands / presence of water in wetlands? 

Unmanned Arial Vehicles (drones) could be the promising future of space technologies and multi-sensor approaches for more accurate and consistent detection of wetlands/presence of water in wetlands. Drones could be a viable option for taking aerial photos of wetlands especially in inaccessible areas. Other promising space technologies can be applied, such as hyperspectral imagery, radar, and Light Detection and Ranging (LiDAR) data. This will increase the accuracy and spot-checking conducted in the field.

Last year you were part of the International Sediment Initiative (ISI) - Training Workshop on ‘River Basin Sediment Monitoring and Management’. What do you see as key thematic areas for capacity-building in developing countries and least developed countries with regards to space technologies for water management?

Particularly for developing countries, capacity building is necessary regarding the use of space-based data and techniques for river hydrology (monitoring soil erosion in the watershed or basin area, sediment deposition in waterbodies (suspended load, bedload rate of suspension sediments, etc.), river morphology, and hydrological characteristics). Many developing countries lack the ability to measure river sediment concentration, suspended load, and bed load, water quality conditions, etc. Furthermore, it limits the ability to conduct research and improve planning. Various stakeholders, including university students beyond the engineering field, must also be trained, and educated on river basin sediment monitoring using space technology. In order to enhance research productivity and impact, financial support such as research grants is essential. It is important for researchers in developing and least developed countries to collaborate with experts from developed countries on research projects and to share their knowledge with them. Sediment control in a watershed is also hindered by the inaccessibility of spatial data for forest management. To achieve a better management of water resources, the use of space technology and data analysis can have a profound effect on science-based policy systems.

If you had three wishes to be fulfilled by a Space Agency, what would they be? 

• Learning opportunities, training, and research collaborations with experts in the field. 
• Grants, fellowships, and opportunities for young researchers to work on space-based data projects related to water management and climate change.
• Space-based data should be more accessible (free, easy to obtain, and readily available) to researchers, academics, and students in developing and least developed countries.

To what extent can space-based technologies and data contribute to the development of rainwater harvesting systems as a strategy for urban stormwater management? Where do you see room for improvement?

There is no doubt that satellite-based technologies and data have influenced the development of rainwater harvesting systems. Space-based technologies allow us to find suitable locations for rainwater harvesting systems. In dense urban areas, high-resolution data is essential for identifying objects and appropriate locations. As a result, better water-sensitive urban designs for stormwater management can be developed as part of policy decisions and urban design plans. Through space-based technology, it is possible to analyse individual lots/roofs' surface areas, soil absorption capacities, and land use patterns, in addition to impervious surfaces. Data collected from space-borne, earth-orbital monitoring equipment like satellites and space shuttles continues to grow, and new software and technologies for analysing them are developing rapidly. Due to more affordable, high-resolution real-time data, urban areas in the global south which lack better stormwater management have been able to implement better rainwater harvesting systems.

Last, but not least, what is your favourite aggregate state of water?

I pretty much enjoy all states of water, but rain and snow are my favourite. I also enjoy watching over cloud patterns in different landscapes while I am airborne.