Croatia launches new satellite water monitoring system to detect pollution in seas, lakes and rivers

Krka

ZAGREB, 4 June (Hina) – The Josip Juraj Strossmayer Water Institute is introducing satellite technology to monitor rivers, lakes and seas, in a move aimed at detecting environmental changes before their effects become visible.

In partnership with Croatian technology company SeaCras, the institute is developing a new system that combines satellite observations with field measurements, enabling simultaneous monitoring of a wide range of water bodies, including large and small rivers, lakes, reservoirs, coastal areas and the sea.

A first pilot project was carried out on the Drava River following the commissioning of one of Croatia’s largest wastewater treatment plants.

According to the institute, a comparison of conditions before and after the plant began operating showed initial signs of improved water quality, with satellite data confirming findings from field monitoring.

Indicators measured included parameters used to assess pollution load and eutrophication, excessive nutrient enrichment, mainly nitrogen and phosphorus compounds that lead to algal blooms, such as biochemical oxygen demand (BOD₅), total phosphorus and chlorophyll levels.

The institute said the system’s high spatial resolution allows monitoring not only of major rivers and lakes but also smaller waterways, enabling surveillance of changes at local, national and cross-border levels.

Institute director Mario Šiljeg said the system for the first time makes it possible to assess the impact of water protection investments not only through infrastructure built, but also through changes in the environment itself.

“Until now we mostly knew how much something cost and what was built. Today we can monitor what happens in the water afterwards,” he said.

He added that experience on the Drava River shows changes can be tracked by combining traditional monitoring with satellite observations. “This is particularly important because rivers are not just watercourses but living systems that respond to pressures, as well as to the measures we take to protect them,” Šiljeg said.

SeaCras, a Croatian technology company specialising in satellite monitoring of waters and seas, is also involved in the development of the system.

European systems already use satellite data to monitor the condition of seas and coastal areas. The approach could also have wide application in the Adriatic, including monitoring the impact of coastal urbanisation, wastewater treatment plants, river inflows, climate pressures and extreme events that leave visible traces in water or sea.

According to the institute, systems that combine satellite data and field measurements could enable earlier detection of environmental changes in rivers, lakes and seas, provide evidence of the impact of investments, and support data-driven rather than assumption-based decision-making.