Hvordan demninger fungerer: En guide til Kypros' vanninfrastruktur

Cyprus has 17 major dams with a combined capacity of approximately 327 million cubic metres (MCM). These reservoirs are the backbone of the island's water supply, collecting winter rainfall and storing it for use throughout the long, dry summer. Understanding how they work helps make sense of the data on the Nero dashboard.

Typer demninger på Kypros

The vast majority of Cyprus's dams are earth-fill dams — massive embankments of compacted soil, clay, and rock that block a river valley to create a reservoir behind them. Earth-fill construction was the standard technique when Cyprus built most of its dam infrastructure between the 1960s and 1990s. Dams like Kouris (completed 1988, 110 metres tall), Asprokremmos (1982, 53 metres), and Germasoyeia (1968, 48 metres) are all earth-fill structures.

The notable exception is Kannaviou, completed in 2005 using roller-compacted concrete (RCC). RCC is a modern technique where a drier concrete mix is spread in thin layers and compacted with vibratory rollers, similar to road construction. It is faster and more cost-effective than traditional poured concrete, and Kannaviou's 75-metre structure benefits from modern engineering standards including advanced monitoring and spillway design.

Hvordan vann lagres og måles

A dam creates an artificial lake (reservoir) by blocking the natural flow of a river. Rainfall in the surrounding catchment area — the hills and slopes that drain into the river — flows downstream and accumulates behind the dam wall. The size of the catchment, the amount of rainfall it receives, and the permeability of its geology all determine how quickly a dam fills.

Reservoir volume is measured in MCM (Million Cubic Metres). One MCM equals one billion litres — enough to fill roughly 400 Olympic swimming pools. The percentage full that Nero displays represents the current stored volume as a fraction of the dam's maximum design capacity. A dam at 50% holds half of what it could theoretically hold if filled to its spillway crest.

Not all water in a reservoir is usable. Every dam has a dead storage volume — the water that sits below the lowest outlet pipe and cannot be physically extracted. When a dam approaches dead storage, it is effectively empty from a supply perspective even though water may still be visible. Evaporation also claims a significant share: during summer, large reservoir surfaces lose substantial water to the atmosphere, with shallower reservoirs losing a higher proportion of their remaining volume.

Den sørlige vannledningen

The Southern Conveyor is the most important piece of water infrastructure in Cyprus. It is a network of pipelines, tunnels, and pumping stations that connects the major dams in the Troodos mountains to the population centres on the southern coast — primarily Limassol, Larnaca, and the Vasilikos industrial zone.

Kouris is the primary source for the Southern Conveyor, supplemented by Kalavasos and Arminou. When these dams are healthy, the Conveyor delivers cheap, gravity-fed surface water to hundreds of thousands of people. When they run low, the system relies more heavily on desalination — which works, but at considerably higher cost and energy consumption.

Avsalting: reserveforsyningen

Cyprus operates several large-scale reverse-osmosis desalination plants that convert seawater into drinking water. These plants now produce roughly 70% of the island's domestic drinking water supply, making Cyprus one of the most desalination-dependent countries in the EU.

The main plants are located at Dhekelia (near Larnaca), Larnaca, Limassol (Episkopi), and Paphos. Together they can produce approximately 80 MCM per year at full capacity. Desalination provides a drought-proof water source that is independent of rainfall, but it comes at a cost: the process requires substantial electricity (roughly 3-4 kWh per cubic metre), and the plants are expensive to build and maintain. When dam levels are high, desalination can be dialled back, saving energy and money. When dams are empty, the plants must run flat out.

Hvordan vann distribueres

Water from dams and desalination plants is distributed through a network managed by the Water Development Department (for bulk supply) and local Water Boards (for municipal distribution). The system serves three main consumer categories:

• Domestic supply (~70 MCM/year) — household drinking water, predominantly from desalination with dam water as a supplement.
• Agricultural irrigation (~150 MCM/year) — the largest consumer. Dam water is allocated to irrigation districts based on reservoir levels. During droughts, agricultural allocations are cut first.
• Industrial and environmental (~20 MCM/year) — factories, power plants, and minimum environmental flows in river channels.

Total annual water demand in Cyprus is approximately 240 MCM. When dams hold more than 40% of their combined capacity, the system can comfortably meet demand. Below 20%, supply cuts become unavoidable.

Gjenbruk av avløpsvann

An increasingly important part of Cyprus's water strategy is treated wastewater reuse. Treated effluent from urban wastewater treatment plants is stored and used for agricultural irrigation, reducing demand on dam water. Achna dam in the Famagusta district is the most notable example — it functions primarily as a storage reservoir for treated wastewater, supporting the intensive agriculture of the Kokkinochoria red-soil region.

Utforsk dataene

Now that you understand how the system works, explore the live data on the Nero dashboard. Click any dam to see its full history, or use the interactive map to see all 17 dams at their geographic locations. For analysis of current trends, visit the blog.