Rapid study of Kakhovka Dam breach impacts will support biodiversity’s recovery

UK scientists’ unprecedented rapid assessment of the environmental impacts of the Kakhovka Dam’s breach will support international action to restore a biodiversity hotspot.

With the area in southern Ukraine in a warzone, the UK Centre for Ecology & Hydrology (UKCEH) and HR Wallingford used cutting-edge technologies to carry out the first independent assessment of the impacts within weeks of the dam being breached in June.

It estimated that half a million hectares of protected freshwater and terrestrial habitats have been exposed to a range of hazards, including nutrients, pollutants from 1,000 sites and the erosion of sediment. This follows widespread flooding downstream and the near-emptying of the upstream Kakhovka Reservoir.

Environmental assessments have previously taken place only after a war, when it is safe for scientists to carry out in-depth field studies, but this has limited the scope of targeted biodiversity restoration within post-conflict recovery planning.

The Kakhovka study, commissioned by the Foreign, Commonwealth and Development Office (FCDO), combined hydrological and digital modelling with satellite imagery and a study of data on the region’s ecology. This enabled the identification of protected habitats and species likely to be impacted by the breach, setting a precedent for early action in future conflicts.

The report’s key findings were:

• Around 83,000 hectares of land, an area the size of Kyiv, was flooded downstream of the dam. The discharge of water was 30,000 m³ per second immediately after the breach, compared to a daily average of 2,600 m³/sec
• The Kakhovka Reservoir was almost completely emptied, leaving thousands of fish washed out or stranded. This included an estimated 28,000 crucian carp, totalling 95,000 tonnes with an estimated commercial value of US $108 million
• There were more than 1,000 potential sources of pollution from flooded sites, including wastewater treatment works, petrol stations, landfills and industrial sites
• The erosion of sediment following the flood might also have released historic pollutants, such as metals, stored in sediments
• The breach affected over half a million hectares of habitats of national or international importance, upstream and downstream of the dam, including the Black Sea Biosphere Reserve
• Some 28 of the 567 species affected by a range of hazards are globally threatened or worse, including the Great Bustard, Pontic Shad, Harbour porpoise, Donets ruffe, the Steppe Polecat, the European mink and the slender-billed curlew, the latter being on the verge of extinction.

Professor Bryan Spears of UKCEH says: “We hope that our assessment provides a baseline against which to assess biodiversity and habitat impacts and recovery related to the Kakhovka Dam breach. It is now important that the results of this and other assessments are scrutinised fully by the wider scientific community, allowing biodiversity restoration to be incorporated within post-conflict recovery planning at an early stage.”

Emma Brown, technical director at HR Wallingford, adds: “I am very proud of the work we’ve done with UKCEH to assess the environmental impacts of the Kakhovka Dam breach. Combining our expertise in dam breach modelling, hydrology and earth observation with UKCEH’s expert biodiversity knowledge enabled the team to produce a detailed report in just 16 days, which I hope will be instrumental in helping with recovery efforts in the region.”

The report, which informed a wider report by the UN Environment Programme, also identified potential long-term effects on the environment, human health and economies. It said the flooding would have worsened water infrastructure and quality, affecting drinking water supply and irrigation for agriculture. The authors made several recommendations for future action (see Notes).

Professor Harry Dixon, Associate Director of International Research and Development, UKCEH, comments: “This significant work undertaken in a timely way using cutting-edge technologies highlights the importance of using science from organisations to inform humanitarian and environmental response to disasters and emergencies across the globe.”

The report is available on the Zenodo website and a commentary by Professor Spears has been published in the journal Nature, Ecology & Evolution (DOI: 10.1038/s41559-024-02373-0).

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Media enquiries

For interviews and further information, please contact Simon Williams, Media Relations Officer at UKCEH, via simwil@ceh.ac.uk or +44 (0)7920 295384.

Notes to editors

Report authors’ recommendations

The report by UKCEH and HR Wallingford recommends an assessment of the sources of radioactive and munitions waste, and their movement down the Dnipro River to the Black Sea. This would support clean-up efforts, reduce the risks to human health associated with eating contaminated fish, shellfish and crops and safeguard a key global grain shipping route if there are unexploded arms in the area.

The scientists at UKCEH and HR Wallingford are now encouraging the international scientific community to work together to build on their initial assessment, to quantify the ecological impacts, provide monitoring programmes, and ensure open access of relevant data.

They call for the rapid development of habitat recovery plans to support species of high conservation, cultural and commercial interest, saying an international scientific response will be required.

About the UK Centre for Ecology & Hydrology (UKCEH)

The UK Centre for Ecology & Hydrology is a world-leading centre for excellence in environmental sciences across water, land and air. Our 500-plus scientists work to understand the environment, how it sustains life and the human impact on it – so that together, people and nature can prosper.

We identify key drivers of biodiversity change, develop tools and technologies for monitoring biodiversity, and provide robust socio-economic and environmental solutions for restoring biodiversity. We investigate the dispersal, fate and behaviour of chemicals and polluting substances in terrestrial and freshwater environments.

The UK Centre for Ecology & Hydrology is a strategic delivery partner for the Natural Environment Research Council, part of UK Research and Innovation.

www.ceh.ac.uk / X: @UK_CEH / LinkedIn: UK Centre for Ecology & Hydrology

About HR Wallingford

We design smart, resilient solutions across the natural and built environments to help everyone live and work more sustainably with water.

By harnessing research, data insights and the power of our collective expertise, we help the world to better understand the changing influence and impact of water.

Drawing on our unique capabilities in science, technology and engineering, we invest in knowledge and innovate to address future challenges and opportunities.

We are the global leaders and independent experts in how to live and work sustainably with water.

www.hrwallingford.com / X: @hrwallingford / LinkedIn: HR Wallingford