Water is life. The Earth's water cycle is a process of constant renewal: waterfalls, water vapour, clouds, rain, springs, rivers, seas, oceans, glaciers... the cycle is never broken. But the engine of life is linkage, and since our origins, water, air and forms of life are closely linked.

Wetlands represent less than 10% of the surface of the planet. Under their calm waters lies a veritable factory, where plants and micro-organisms filter the water and digest all the pollution. These marshes are indispensable environments for the regeneration and purification of water. They are sponges that regulate the flow of the water: absorb it in the wet season and release it in the dry season.

Danube Delta is one of the biggest wetlands in the world, habitat of the waterfowl, and the only delta entirely declared as Biosphere Reserve.

Shared between Romania (about 75% of the area) and Ukraine, the delta region includes extensive examples of unaltered rivers, reed beds, marshes, steppes, dunes, shingle bars, coasts, lagoons, saltmarshes and climax forests. The mosaic of habitats developed is the most various in Romania, hosting a great variety of communities of plants and animals:*

• wetland biodiversity with 30 types of ecosystems, 23 natural and 7 created by man;
• over 7400 species - many of them rare or missing in other European areas;
• rich fish fauna (75 species), including several species of sturgeon, and important populations of several mammals;
• the biggest area of compact reed beds on the planet.

Started in the 70’s, the powerful ecological forces that underlie the Delta’s productiveness were threaten by the so-called “complex development plan” initiated by the communist regime. The biological, chemical and physical systems were subject to rapid and severe degradation, as result of over-development for navigation, fish farming, agriculture, forestry and flood control.  

Soon after 1989, the new administration ceased further damaging works in the delta, and since September 1990 Danube Delta is listed as Wetland of International Importance, under Ramsar Convention - the only international treaty devoted to a single ecosystem type - wetlands protection.
The essence of the Ramsar philosophy is the “wise use” of wetlands, meaning conservation and sustainable use of wetlands and all the services they provide, for the benefit of people and nature. Romania has 19 Ramsar Sites, most of them being located down the Danube river and on Delta region. Its natural heritage value is also recognized by the inclusion in the strictly protected areas - World Heritage Site and UNESCO Biosphere Reserve.

Programs for Delta’s conservation has been initiated in the last decades, and starting with the satellite imagery provided by the Copernicus Sentinels the monitoring efforts are hugely improved.

Wetland Water Monitoring - Hydro-Sar - is a prototype service developed by TERRASIGNA in cooperation with the National Institute for Research and Development of Marine Geology and Geoecology (GeoEcoMar), and commissioned by the European Space Agency. The project addressed several wetlands monitoring issues:

• mapping the surface water extent (including flooded vegetation);
• water level changes and flow directions maps;
• change detection analysis (coastal area, floating reed beds etc.).

In image - interferogram over Danube Delta, Romanian area, March 2015
The area of interest covered the wetland vegetation and the open water distributed in an intricate pattern of marshes, channels, streamlets and lakes. Optical and Synthetic Aperture Radar (SAR) images were used in order to provide complementary information regarding the wetland water dynamics.   

The interferograms - multiple SAR images linked in order to illustrate changes between radar scans - reveal various hydrological parameters: water flow directions, wetlands dynamics, water level variations between different dates.

In-situ measurements and observations in wetlands areas are not easy tasks, and water cycles regimes are difficult to comprehend in such conditions. The level of details that satellite images provide exposes a lot of unobservable connections between water bodies, and the hydrological models can be significantly improved.

The pressure on wetlands is still present, as economic interests represent constant needs.
By monitoring and conserving wetlands diverse ecosystems, we protect life.

*Statistics Danube Delta Biosphere Reserve Authority