The drainage of the channel connected to the natural Lake Kournas is attributed to the presence of a sinkhole that formed along a trench northeast of the lake.
Following a request from the Deputy Mayor of Apokoronas, Mr. Ioannis Apostolakis, a team from the Regional Unit of Crete of the Hellenic Survey of Geology and Mineral Exploration (H.S.G.M.E.) carried out a series of field inspections in the area to identify the causes of the channel’s drainage toward the dam.
Fig. 2: View of Lake Kournas from the geological map of H.S.G.M.E.
On October 15, 2021, the day after the official request from the Municipality of Apokoronas, the H.S.G.M.E. team visited the lake. Field inspections continued over the following days until the end of the month. Old wells and irrigation channels once in use were examined, along with the Delfinos River, which serves as the lake’s natural surface outflow. On October 25, 2021, the precise location and cause of the channel’s drainage were identified.
Specifically, within the trench and beneath a thin layer of saturated sediments (alluvial deposits), the mouth of a sinkhole was located inside a funnel-shaped depression composed of weakly consolidated colluvial material. The sinkhole formed within cohesive clayey-marly deposits, with drainage occurring vertically downward. The sinkhole’s opening measures approximately 0.35 m x 0.25 m and has an elliptical shape.
Fig. 3: Area where the sinkhole is located at Lake Kournas.
On Friday, October 29, 2021, a coordination meeting of the competent authorities was held at the Apokoronas Town Hall to manage the situation, attended by the Head of the Regional Unit of Crete, Giannis Michalakis.
The Hellenic Survey of Geology and Mineral Exploration (H.S.G.M.E.), through its Regional Unit of Crete, remains in constant communication with the relevant authorities to monitor and assess the risks associated with the phenomenon and to determine the necessary measures to prevent further drainage.
Fig. 4: The H.S.G.M.E. Crete Regional Unit team conducting multiple on-site inspections in the area.