SDG 6. Clean water and sanitation

Monitoring the water regime of wetlands from Space helps us protect water ecosystems

Iphigenia Keramitsoglou, Research Director
National Observatory of Athens, Greece

Mapping the water regime of wetlands is a very challenging task. Some wetlands are always flooded whereas others are only seasonally or rarely flooded. These changes make wetlands very dynamic ecosystems. As Low Earth Orbit satellites acquire images every few days, they can be used to monitor this dynamic behaviour.

Interview

Iphigenia Keramitsoglou
Photo: Jonnek Jonneksson

I am a Research Director in Satellite Earth Observation at the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory in Athens, Greece.

My field of action is processing satellite images of the Earth with the ultimate goal to develop satellite-based operational services for environmental applications, so that this new information acquired from Space is actually usable and can be used by organizations and citizens.

Wetlands are parts of our landscape and are defined by the presence of water.

They are among the most productive ecosystems in the world. The biodiversity of wetlands and the economic activities they support depend on the flood period and quantity of water.

These require systematic monitoring to understand their evolution and management requirements. Both change over time.

The Balkan Mediterranean territory is full of lake complexes, inland and coastal wetlands as well as riverine systems. They are ALL of high conservation value. Despite their importance, knowledge of these wetlands is scattered and incomplete.

Glacial Lake Ribno Bunderishko Ezero (Bulgaria).
Photo: Blagoy Uzunov

This was the motivation behind a project called “Improving the conservation effectiveness of wetlands“, shortened to WetMainAreas. The project was launched in September 2017, under the Balkan-Mediterranean transnational cooperation programme 2014-2020 co-funded by the European Union and national funds of the participating countries. Its main goal is to contribute to the protection, conservation and development of wetlands, as a shared asset of the Balkan-Mediterranean territory.

It comprises partner institutions from 4 different countries in the territory (Bulgaria, Greece, Albania and North Macedonia). Participation from these countries has helped to overcome national borders and to build shared knowledge about wetlands and transnational ecosystems. Although Cyprus was not represented in the partnership, the project covers also this country.

Why are we using space to monitor the water regime of wetlands?

Messolonghi lagoon in Greece as seen by Copernicus Sentinel-2
Photo: European Union, Copernicus Sentinel-2 imagery

Mapping the water regime of wetlands is a very challenging task. Some wetlands are always flooded whereas others are only seasonally or rarely flooded. These changes make wetlands very dynamic ecosystems. As Low Earth Orbit satellites acquire images every few days, they can be used to monitor this dynamic behaviour.

For this work we have been collaborating closely with my colleague and dear friend Eleni Fitoka, who is responsible for the Natural Areas inventory at the Greek Biotope Wetland Centre of the Goulandris Natural History Museum.

We have worked closely together – one expert in Space and one expert in wetlands – to set up a methodology for monitoring the water regimes of the Balkan-Mediterranean wetlands. Later, this led to the development of the operational satellite Earth observation service.

To develop this service we have used two identical European satellites, Copernicus Sentinel 2A and 2B. All the water and wet areas in the five Balkan-Mediterranean countries were mapped with a pixel size of 10 meters.

The work has two distinct phases.

The first phase is to identify the water and wet areas and use this information to update the national databases of wetlands. This phase revealed the presence of small, unregistered wetlands in remote and unreachable areas.

After the national databases were updated, we used these locations to set up the monitoring service. When Sentinel-2 passes over a wetland, a new image is downloaded. Then the spectral bands are processed, and several water indices are calculated. The statistics of the wetness and water presence per pixel give the status of water permanency.

Lake Kerkini in Northern Greece seen from Space. It is one of the Ramsar Convention wetlands. The seasonal differences are impressive as seen in the three acquisitions by Sentinel-2 on 15/12/2019 (left), 8/4/2020 (middle) and 7/6/2020 (right).
Photo: European Space Agency

Over time, the database has filled with more images increasing the statistical value of the results.

The service provides a time series with all the satellite images available. Statistical analysis per pixel can reveal the periodicity, extent and duration of flooding as well as occasional or extreme flood events.

So far, using three years of data from 5 countries acquired by two satellites, we have monitored the water regime of more than 8600 wetland sites.

One of the targets of Sustainable Development Goal Number 6 for Water is to protect and restore water-related ecosystems, including wetlands and lakes. In particular, the proposed Indicator 6.6.1 monitors change in the spatial extent of water-related ecosystems over time.

Towards that end, WetMainAreas has integrated thousands of natural and artificial wetlands in its database.

These cover approximately 2% of the Balkan-Mediterranean territory. We should note that the highest proportion of the wetland spatial extent (80%) is designated as internationally important according to the Ramsar Convention or the NATURA 2000 and Emerald networks.

A key question is which entities can benefit from using the satellite water monitoring Service.

The service supports policy and action plans for wetland ecosystems and has improved the capacity of authorities, regional planners and developers to take informed decisions and to cooperate towards ecosystem integration and sustainability.

For instance, the Bulgarian Ministry of Environment and Water has already used the information for national reporting and updating the national Information Sheets on Ramsar Wetlands. At the same time, experts from various organisations use the digital information in strategic environmental impact assessments.

Gallery

Détail de la carte du régime hydrique du lac Kerkini. La taille des pixels est de 10 m. Le régime hydrique de toutes les zones humides de la Méditerranée balkanique a été cartographié avec cette précision.
Tableau de bord pour le suivi du régime hydrique des zones humides depuis l'Espace. Sur la gauche, l'utilisateur peut trouver la zone humide qui l'intéresse parmi plus de 8600 zones humides.
https://vimeo.com/557963443
https://vimeo.com/557962157
Messolonghi lagoon in Greece as seen by Copernicus Sentinel-2
Messolonghi lagoon in Greece as seen by Copernicus Sentinel-2 Photo: European Union, Copernicus Sentinel-2 imagery
Détail de la carte du régime hydrique du lac Kerkini. La taille des pixels est de 10 m. Le régime hydrique de toutes les zones humides de la Méditerranée balkanique a été cartographié avec cette précision.
Detail of Lake Kerkini water regime map. The pixel size is 10m. The water regime of all the wetlands in the Balkan-Mediterranean region has been mapped with this accuracy. Image: National Observatory of Athens
Tableau de bord pour le suivi du régime hydrique des zones humides depuis l'Espace. Sur la gauche, l'utilisateur peut trouver la zone humide qui l'intéresse parmi plus de 8600 zones humides.
Tableau de bord pour le suivi du régime hydrique des zones humides depuis l’Espace. Sur la gauche, l’utilisateur peut trouver la zone humide qui l’intéresse parmi plus de 8600 zones humides. Image: National Observatory of Athens
Lagune de Messolonghi en Grèce.
Lagune de Messolonghi en Grèce. Image: DroneRoad
Lake Kerkini in Northern Greece seen from Space. It is one of the Ramsar Convention wetlands. The seasonal differences are impressive as seen in the three acquisitions by Sentinel-2 on 15/12/2019 (left), 8/4/2020 (middle) and 7/6/2020 (right).
Lake Kerkini in Northern Greece seen from Space. It is one of the Ramsar Convention wetlands. The seasonal differences are impressive as seen in the three acquisitions by Sentinel-2 on 15/12/2019 (left), 8/4/2020 (middle) and 7/6/2020 (right). Photo: European Space Agency
Glacial Lake Ribno Bunderishko Ezero (Bulgaria).
Glacial Lake Ribno Bunderishko Ezero (Bulgaria). Photo: Blagoy Uzunov

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