COULD THE TOLISA RIVER RETURN TO ITS FORMER COURSE?

After more than half a century since it was drained, the old course of the Tolisa River could once again carry water, bringing back ponds, oxbows and wetland habitats that were once an integral part of the Posavina landscape.

PHOTO: Glas Srpske

The restoration could benefit not only the natural ecosystem but also local farmers, who have increasingly struggled with a lack of water for irrigation in recent years.

The restoration of this former river system is being planned by the Society for Biodiversity Research and Protection from Banja Luka and the Municipality of Modriča, as part of the European “DaWetRest” project, funded through the Horizon programme. The project is worth €75,000 for this associated region.

THE FIRST STEPS TOWARDS RESTORATION HAVE ALREADY BEEN TAKEN

Although the restoration is a long-term undertaking, the first steps have already been made. Field research has been carried out, data collected, and discussions held with institutions and residents living along the former river course.

The Tolisa once meandered for more than 70 kilometres through Posavina, between Brčko, Šamac, Modriča and Orašje. In 1974, during a period of major agricultural development projects, the river was cut off and drained

Its water was redirected into a network of canals, while parts of the former riverbed were converted into agricultural land.

Today, the situation is different. Some areas once used for agriculture have been abandoned, water resources are becoming increasingly scarce, and climate change is further intensifying drought.

The dry and poorly maintained land in these areas is also increasingly vulnerable to fires, with hundreds of fires breaking out every year and their number continuing to rise.

For this reason, the idea of returning water to the former river course emerged from the Posavina villages themselves, explains Jovica Sjeničić of the Society for Biodiversity Research and Protection.

“People from these villages told us that when the Tolisa was flowing, there was more life and more opportunities for agriculture. There were ponds, people could fish, and there was much more wildlife. Today, on the other hand, the lack of water is becoming increasingly noticeable,” Sjeničić said.

WATER WOULD BE RETURNED TO THE OLD COURSE IN A CONTROLLED WAY

Restoring water to the former riverbed does not mean simply releasing water back into the Tolisa.

The idea is to manage the entire system in a controlled manner, providing water during dry periods while also reducing the risk of flooding.

“We propose building a sluice on the canal that drained the Tolisa, allowing water to be gradually and controllably directed into the former river course and used to refill ponds and oxbows,” Sjeničić explained.

“In some areas, cleaning, deepening and sediment removal will also be necessary. We are also considering the possibility of replenishing the system with groundwater and through pumping,” he added.

Field research should determine where such measures would have the greatest impact.

The collected data have now been incorporated into a large GIS database containing information on the former river course, canals, ponds and oxbows, as well as the condition of natural habitats and water resources and other information important for restoration.

“We are now preparing a restoration measures plan and trying to determine priorities. We have spoken with representatives of the Ministry of Agriculture, Forestry and Water Management, ‘Vode Srpske’, local authorities and local communities, because this is a task that requires cooperation between several sectors,” Sjeničić said.

PREVIOUS RESEARCH SHOWED THAT WATER CAN BE RETAINED

Earlier research has also shown that water can be retained in certain parts of the former river course.

One of the project collaborators, biologist Ana Ćurić, worked on a pilot project aimed at restoring several ponds along the old Tolisa course, where the possibility of retaining water in the riverbed was examined.

The experience gained through that project is now one of the foundations for the wider restoration plan.

However, the challenge is not only the quantity of water but also its quality.

“In some places where there is no population, the water is of good quality. However, tributaries flowing through villages and agricultural and industrial areas are affected by organic matter, sewage, heavy metals and pollutants from agriculture. That is why we also have to address the issue of water treatment,” Sjeničić said.

FARMERS HAVE BEEN FACING WATER SHORTAGES FOR YEARS

The restoration could bring tangible benefits to local communities, in addition to protecting wetlands and restoring habitats for wildlife.

Farmers have been dealing with water shortages for years, and a restored water system could create new opportunities for irrigation, while controlled water retention could also help during periods of heavy rainfall.

“Groundwater levels have fallen, there is very little surface water, and farmers have been struggling with shortages for at least 15 years. If we secure a reliable water supply, we will have opportunities for irrigation as well as better flood control,” Sjeničić stressed.

PONDS, FISH AND BIRDS COULD RETURN TO POSAVINA

More water would also create better conditions for fishing and hunting, while providing habitats for birds, fish and other species.

The goal is for the former river course to once again become a connected system of ponds, oxbows and water bodies, rather than a series of isolated canals and dried-out riverbeds.

However, concrete restoration works are still some time away.

The restoration plan is currently being completed and is expected to be adopted by the end of the year. After that, funding for implementation would be sought through new project calls.

“This is being done in phases and as a long-term process. We are now laying the foundations for the next project, which would involve concrete restoration works. Over the next few years, we expect that more substantial work could begin in the field,” Sjeničić said