Syros, Greece

Description

Syros is a Greek island in the Cyclades (Aegean Sea) with an area of 83.6 km² and a population of 21,124 people (2021 census). The island's drinking water supply network, sewer system and wastewater treatment plants (WWTPs) are managed by the Municipal Water Supply and Sewerage Company of Syros (DEYAS). The drinking water supply network largely relies on reverse osmosis seawater desalination plants, with a total supply of 1.7-2.2 hm³/year (including the network losses), while groundwater can also contribute to a much lesser extent. For 2023, the desalination plants and the groundwater abstractions accounted for 96% and 4%, respectively, of the water supplied by DEYAS (data by DEYAS). The irrigation demands, on the other hand, are largely covered via groundwater abstractions. Currently, a relatively small quantity of wastewater that undergoes tertiary treatment is used for Managed Aquifer Recharge (MAR) and irrigation while interventions related to AWR are being examined. Those are extension of wastewater reuse for MAR and irrigation and extension of Rainwater Harvesting (RWH) installations on the island to alleviate the pressure on the other water sources. Additionally, increase of desalination capacity is also considered and examined. Similar to other Greek islands, harvesting rainwater is not a new practice for Syros. Rainwater cisterns have been traditionally used in the island, and some are still in use today.

For the purpose of RECREATE project, a systemic modelling approach that integrates different tools to assess baseline and AWR implementation under climate change uncertainty and different socio-economic scenarios while taking into account water – energy interactions, combinations of technologies, pricing mechanisms, seasonal demand options and water-related behaviours is being deployed. This is achieved by exploiting the model capabilities of the Urban Water Optioneering Tool (UWOT), the System Dynamics and the Agent-Based Modelling. Utilising the above tools, RECREATE approach applied in Syros starts from SSPs to regional evolution and eventually to system perform. AWR interventions’ assessment and planning is supported by a stress-testing framework and a state-of-the-art adaptation pathways module (including genetic algorithm optimization approaches but also Reinforcement Learning).

MAR activities are also implemented in the island with significant impact to stakeholders, especially the farmers. Community of Practice activities implemented and planned in the island support the acceptance of AWR and their upscale and transferability potential.