Description of the application

Rapentosa dam is a detention dam which also assists in sediment retention and it is located 6.1 km upstream of Rapentosa river basin (Marathon area, Attiki region). The main objective was the flood protection of the downstream areas (Nea Makri and Marathon's coasts) and especially the protection of the Athens' Marathon Route during the 2004 Olympic Games. The construction of the dam was finalized in 2005 and the project planning budget amounted to 2.237.000.000 drachmas (almost 6.600.000 euros). The responsible authority was the Athens Water Supply and Sewerage Company whereas the METRO ATE Company undertook the construction. The type of dam is concrete-face rock-fill dam. The main dam and reservoir characteristics are: Height: 39 m Crest Length: 144 m Crest width: 5 m Volume: 127.000 m3 Reservoir capacity: 1,26*106 m3 Catchment area: 25 km2 Spillway capacity: 200 m3/s

Lessons learned

Due to construction reasons, the location of the dam was not near the outlet of the Rapentosa Basin area but 6.1 km upstream. Therefore, still great portion of the river basin drains without retention causing flood problems to the downstream areas in case a high intensity precipitation event occurs. On November 22nd -25th of 2005, the inundation of the low lying areas led to angry reactions of the general public and the function/usefulness of the dam was questioned even though the dam fulfilled its purpose according to studies i.e. caught surface runoff and reduced the flow peak. Consequently, even though Rapentosa dam assists in the detention of the surface runoff, it does not fully ensures flood protection of the downstream areas.

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Last modified: Sept. 13, 2016, 3:59 a.m.