Denmark river restoration fails to bring back lost habitats

The Story in Brief

Denmark's Rs 1,500-crore project to restore River Skjern has failed to fully recreate lost habitats, with researchers warning natural processes could take centuries. A study in Ecological Engineering found that after turning 19 km of straightened river into 26 km of winding channel in 2001, only 5.8 per cent of original backwater habitats were restored. The river channel changes much slower than expected, with models predicting just 6.8 metres of bank retreat over 100 years.

While aquatic plants and sensitive insects like mayflies recovered within a year, species dependent on quiet backwaters have not returned. Aarhus University researchers say total biodiversity remains below pre-1960s levels, when the state drained wetlands for farming. They recommend active biological and physical interventions to speed up recovery, which could otherwise take decades or centuries. The project, meant to reverse damage from the 1960s drainage, shows limits of relying on natural processes alone.