Research and Development

Independent assessment reveals impacts of Kakhovka Dam breach

Tags
Independent assessment reveals impacts of Kakhovka Dam breach
(photo courtesy Ukrhydroenergo)

UK scientists have performed a rapid assessment of the environmental impacts of Kakhovka Dam’s breach that they say will support international action to restore a biodiversity hotspot.

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 in southern Ukraine being breached in June. It estimated that half a million hectares of protected freshwater and terrestrial habitats were 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 Kakhovka Reservoir.

Previously, environmental assessments have 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 — 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.

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/sec immediately after the breach, compared to a daily average of 2,600 m3/sec
  • 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
  • Erosion of sediment after 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
  • 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, Steppe Polecat, European mink and slender-billed curlew, the latter being on the verge of extinction.

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

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.

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