Water shortages have now become an established feature of the summer season in Crete. So far they have chiefly affected water for irrigation purposes, but with the construction of increasing numbers of large hotel complexes on the island, it cannot be long before domestic water supplies are also affected.

Poor infrastructure maintenance
Apart from the increasingly mild winters, which produce insufficient rain to fill the island’s reservoirs, a major contributing factor is the poor management of the existing water infrastructure. Leaks abound, and new reservoirs remain unused or uncompleted. The Valsamiotis dam near Vatolakkos, south west of Chania, was constructed with EU funds between 2005 and 2014 at a final cost of over €40 million. The largest of its kind in Greece, it had a designed capacity of 6 million cubic metres, and it was considered that it would cover much of the irrigation needs of the plain of Chania. Unfortunately, when it started to be filled it was found to leak to an unacceptable level, and has remained inoperative, successive attempts to find a solution having so far failed.

Another major source of irrigation water, the lake of Agia, is also an important wetland and wildlife refuge, whose function as such depends on its maintaining a certain water level. Following a warning from the EU over dropping water levels, an inspection revealed that there were two leaks, one from a sluice gate and the other from a valve installed by DEI when the small hydroelectric generating unit was in operation. Action is being take to remedy both leaks, but a further problem which needs addressing is the fact that sediment deposited by the water flow has greatly reduced the volume capacity of the lake.

To these major distribution problems must be added the probably thousands of small leaks in irrigation networks across the island.

The pros and cons of water desalination
Desalination is commonly used in many arid parts of the world, to treat both seawater and ground water with a high salt content. It has often been put forward as a possible solution to the water problems in Crete, but as a leading expert has told Haniotika Nea, it is not a magic solution.

Interviewed by the paper’s managing director Paraskevas Perakis, Assistant Professor in the School of Chemical and Environmental Engineering at the Technical University of Crete Alexandros Stefanakis explained that while desalination could make an important contribution to water supplies in Crete, it needs to be part of a complex of solutions.

Mr Stefanakis explained that desalinated sea water is not suitable for immediate human consumption, but is generally used for irrigation. To be made drinkable it requires further processing, which adds to the already elevated cost. Currently, desalination is chiefly carried out by reverse osmosis and is suitable either for small units which can be installed in hotels, or very large ones which can supply whole cities such as Chania.

There are also new systems developed by the Technical University of Crete, the professor said, which use a process of solar desalination. “This system can provide a solution in areas where even the water which reaches our taps is saline.” Desalination can also be applied to water from boreholes or from saline springs, however this only exacerbates the problem over time as it increases the ingress of seawater into the water table.

The disadvantages
The process of desalination itself has disadvantages, chiefly that it is an energy-intensive process with high operational costs. “Each cubic metre of water needs 1 to 1.5 kilowatt hours of electricity, while until a few years ago the cost was five times as high,” Mr Stefanakis said. For this reason the Gulf States, which have invested intensively in desalination, build their installations next to energy generating plants.

As regards the use of renewable energy sources, Professor Stefanakis explains that while it is possible, it requires planning to ensure access to the grid, while the use of batteries increases the operational and maintenance costs.

Environmental footprint
A major problem of desalination is that its by-product, salt, cannot be reused and the normal practice is to discharge it into the sea. This has negative effects on biodiversity, which means that such units cannot be installed in Natura areas, nor those with Posidonia seagrass meadows. At the same time these units produce sound pollution, while the need to situate them in coastal areas can have environmental consequences, as well as restricting citizens’ access to the beaches.

Alternatives
According to Professor Stefanakis, both Crete and Greece as a whole require a complex of solutions to the problem of drought, of which desalination is one. Especially in Chania, he says, the priority must be the modernisation and maintenance of the supply networks, since in some cases losses are as high as 50 per cent. “If we solve that issue, we will have made a tremendous step towards economising water use,” he says.

Also important is the use of effluent from sewage works. In Chania, the professor says, the effluent is processed and discharged into the sea, whereas it could be used for irrigating crops. This is something which should have been foreseen years before: at the moment the reuse of water from sewage works in Greece is only 2 to 3 per cent, while in Europe generally it is no more than 10 to 15 per cent.

The need for a comprehensive solution
What emerges from the discussion with Professor Stefanakis, Mr Perakis concludes, is that Chania and Crete generally need a serious strategic plan which will involve both local government and the State, as well as the scientific community who have the necessary technical know-how. On this basis immediate decisions need to be taken to determine the future of water resource management in Crete.