Communal rainwater harvesting framework for reducing water scarcity and desalinated water production in arid and semi-arid islands.

Climate change and its effects on water availability call for innovative and sustainable solutions for tackling water scarcity and drought in arid and semi-arid regions. Arid regions, grappling with the complex interplay of climate change, population growth, and heightened demand for water resources, demand a paradigm shift in the way we approach water management.

The island of Syros and the Cyclades region, in general, are historically affected by drought and water scarcity. To tackle these phenomena, the local communities have been dependent on alternative water resources, mainly rainwater harvesting and seawater desalination. Over the past years, managed aquifer recharge from reclaimed wastewater is also tested and implemented to increase the water safety of the island. The performance of a rainwater harvesting (RWH) system depends on various factors such as the amount of rainfall, the size and design of the system, the quality of the water collected, and the demand for water. Although RWH is embedded to the local architecture (flat roofs and built-in water reservoirs), not all buildings have the capacity to collect the maximum water for precipitation. These buildings represent all public buildings and buildings with limited storing capacity. Adding these buildings to the equation, the local community is closer to the RWH potential of 50 m³/capita per annum. Such communal rainwater application will reduce the demand on desalinated water production, especially outside the touristic period, resulting on decreasing energy needs and consequently CO₂ emissions. 

This work explores a visionary approach to addressing the water crisis in arid islands, advocating for the design of a communal rainwater harvesting administration and implementation framework tailored to the unique needs of arid and semi-arid islands. Such application will increase the water safety of these areas, while decreasing the environmental impact of energy demanding alternative water resources.