The Kifissos River, the Attica Basin’s primary floodwater conduit, is dangerously close to exceeding its capacity, experts warned at a conference hosted by “Flow Association – Citizens for Streams.”
Immediate measures, such as upstream natural water retention and enhanced rainwater infiltration in urban areas, are needed to mitigate risks.
Hydrogeologist Dimitris Zarris revealed findings of a third underground “lake” caused by erosion in the Kifissos’ concrete-lined bed.
“No one expected concrete to erode. A small defect in the cement suffices – water pressure then destroys the riverbed, forming these lakes,” he explained.
Zarris noted the river’s flow capacity stands at 1,400 m³/sec, but under extreme weather, volumes could exceed 2,200 m³/sec, leading to overflows in Faliro, Moschato, and upstream areas like Kokkinos Mylos.
“We must reduce peak water flow during heavy rainstorms,” he said, urging “natural” interventions near the Kifissos’ source and improved urban drainage systems.
Municipalities should expand permeable surfaces, such as sidewalks and parking lots, to allow more water infiltration.
“Every municipality could aim to cut stormwater runoff by 20% within a decade,” Zarris added.
Conference participants criticized state policies favoring concrete canalization, such as recent plans to underground the Stamatis stream in Dionysos, calling them counterproductive.
“Taxpayers pay for solutions that encourage illegal construction,” Zarris remarked.
Highlighting past flood catastrophes, Christina Filippa of the association said, “I am afraid that the problem is still relevant, as is our commitment to primitive techniques for the streams.”
While praising Attica’s recent flood master plan for cataloguing infrastructure, attendees noted it lacks innovative approaches that preserve natural stream environments. European flood control methods, prioritizing natural systems over technical fixes, were cited as the gold standard.