Case study Cyprus: Artificial recharge of tertiary cleaned wastewater

The Ezousas aquifer is a confined river aquifer close to the sea in the southern part of Cyprus, and it delivers groundwater to a number of private wells for irrigation. During the latest years precipitation in Cyprus has in general decreased by around 20% resulting in reduced groundwater recharge. Beside, a dam was recently constructed upstream the river, resulting in low groundwater table downstream. This is due to the fact that the aquifer is used intensively for irrigation during summertime and not recharged by the river as there is hardly any flow during the dry season. Besides, the precipitation and groundwater recharge during the wet season is not sufficient to compensate for the abstraction. Additionally, private wastewater recharge that earlier contributed to some extent to local groundwater recharge in the area is closed and the wastewater is now led to a public wastewater treatment plant. All these factors have caused the groundwater table to drop drastically inducing water quality problems by saline water intrusion from the sea. To reverse this development, tertiary cleaned wastewater is artificially recharged to the Ezousas aquifer in ponds to increase the amount of available groundwater for irrigation. The groundwater is mixed with water from the river upstream the dam at a ratio of 1:20 and used for irrigation both locally as well as exported to a neighbouring region. The dominant crop in both areas is citrus trees. Domestic water supply is based on dam water and not on water from the Ezousas aquifer.