The region of Halkidiki, which in any case has problems with this water supply For various reasons, as recently made clear by the several-day interruption of the water supply in Pefkohori, the country is increasingly facing the “beast” of so-called waterlogging. This is a phenomenon related to the excessive pumping of water in coastal areas to cover their needs. agriculturebut to a lesser extent tourism and residential development. The problem is multifactorial. The thousands of wells, both legal and illegal, operate “at full capacity” during the summer months.
At the same time, it is a common secret that the land of Halkidiki has been “ploughed” for decades by illegal networks, built by private individuals, which illegally transport water from wells up to kilometers away – while the law allows it to be transported up to a maximum distance of 800 meters. The irrational use of water, but also climate crisiswhich in many areas has reduced the underground water table level by up to 10 meters, approximately the height of a four-story apartment building, also contributes to the flooding phenomenon.
How is the drop in groundwater levels linked to salinity? In very simple terms, freshwater acts as a kind of “barrier” for marine life. So when its level drops too low, seawater penetrates inland, as this dam “falls” because the natural hydraulic gradient towards the sea is reversed. The problem is not new, but it has been getting worse in recent years.
“We have been dealing with flooding for years. The very rapid development of intensive olive farming in our region, especially since the end of the 1990s, combined with the lack of rain and prolonged heat waves, which increase the need for irrigation, have made the problem worse,” the mayor told APE-MPE. Georgios Emmanuel, the town’s chief of Polygyros, explains: “The town of Polygyros used to be supplied with water from the Kalyves plain, which is close to the Olynthios River. However, in the last 20 years, olive cultivation has been growing and thousands of new trees are planted every year, which means that irrigation needs are also increasing. At the same time, water is transported irregularly from boreholes over very long distances, even kilometres, to irrigate the fields. A fixed borehole with a yield of 10 cubic metres can irrigate 100 hectares, one with a yield of 100 cubic metres, 1000. Then when there is excess water, it is transferred elsewhere. Legally it can be transported up to 800 metres, but it is an open secret, a practice that has been practiced for decades, that water often travels kilometres, transported through illegal networks built by private individuals.”
If the illegal exploitation of olive trees is a clearly reprehensible phenomenon (the exact number remains unknown), the continuation of olive cultivation in Halkidiki is certainly necessary. “We cannot put farmers on the other side of the street and kill them. On the contrary, serious investment is needed in smart agriculture, which can limit unnecessary waste of water, but also in more rational use of water, for example, drip irrigation instead of nozzles, with the use of which a large part of the water evaporates, but and irrigation according to the special needs of each crop and not horizontally,” notes the mayor of Polygyros, stressing that in the area under his responsibility the agricultural sector currently absorbs 90% of the water, compared to a rate of up to 10% for tourism and residents together (it is clear that tourism and citizens require drinking water of very high quality, unlike the primary sector).
According to Emmanuel, we need to look at the issue holistically, for example, instead of pumping excessively through boreholes, “the water from biological purifications can be used after treatment for irrigation, to create a water storage”, which of course requires the necessary biological cleaning projects, many of which are still missing, but also the creation of sewage networks that will be connected to the biological ones (which are also missing in many areas). It is also necessary to modernize the water supply networks, which on the Polygyros coastline are in some cases more than 50 years old, which means that at least 40% of the water is lost due to leaks due to age, and in addition, water theft is easy. For all this to continue, considerable funding is obviously needed, which is not always easy to obtain for various reasons.
The desired “peaceful rain” and the water flows that Greece does not control
The problem of salt water in general is very widespread in Greece, due to the long length of its coastline, as Professor Emeritus of the Department of Civil Engineering at the Aristotle University of Thessaloniki (AUTH), Konstantinos Katsifarakis, told APE-MPE. The problem, which is evident on almost all the islands, including Crete, mainly concerns groundwater, but there is also saline intrusion in the estuaries. With the exception of areas such as Halkidiki, but also Pieria, where crops and tourism often coexist by the sea, the problem of salt water is not particularly related to agriculture. “It has to do mainly with tourism – due to the temporal and spatial concentration of water consumption, four months a year, in specific areas – but also with the residential development of these areas. In some cases, such as in the north-east of Halkidiki, mining activity also plays a role, which also requires a lot of water”, explains the professor.
How is flooding related to falling groundwater levels? “They are absolutely interconnected, because for seawater to penetrate inland, there is no need for a freshwater “dam”. So if the water level drops, the sea “comes in”. And climate change is certainly having an effect. We have long periods of drought, but also heavy rains, which cause flooding – in Volos, last year, it poured out as much water in two days as it does in a year, but what to do with this water – as for water? The table that needs to be enriched is “quiet rain”, gentle rain”, he observes. Today, in some areas of northern Greece the water level has dropped by more than 10 meters, while in parts of Thessaly it is much higher, which is not unusual in recent years, the professor notes. In response to the question of what volumes of water the annual water deficit in Northern Greece is calculated in, Mr. Katsifarakis explains that we cannot speak of a deficit throughout the year, since the problem is localized (in specific areas with many tourist arrivals) and seasonal (the months of the tourist season with the highest demand). In addition to spatial and temporal concentration, the problem is also related to the fact that Greece does not fully “control” many of its water “pipes”.
With the exception of the Aoos, which originates in Greece and continues its course in Albania, all other cross-border rivers that flow through northern Greece originate in other countries. As a result, Greece is dependent on the management of its river waters by neighbouring countries. In particular for Thessaloniki, Mr Katsifarakis points out that although the sea has long since penetrated the basements of buildings located close to the sea (e.g. on Nikis Avenue), it makes no sense to talk about flooding in the urban fabric. Thessaloniki is supplied with water from Aliakmonas and Arabissos and there are only boreholes in a few stadiums in the city.
Natural decontamination takes months or even years
Salivation is considered pollution because when salt infiltrates freshwater, it can no longer be used by humans for its most common purposes. Is it easy to clean up? “Natural decontamination is a slow process, because it takes months or even years for the freshwater level to rise. In the case of desalination, the issue is not time, but energy expenditure. Even for decontamination with reverse osmosis, a lot of energy is needed to obtain clean water,” Katsifarakis points out. More appropriate, he believes, are preventive measures, such as enriching the water table by storing groundwater through small dams, “as the great Manolis Glezos did in Aperathos, Naxos”.
In coastal areas, where new tourist resorts are being developed, some simple but important measures could also be implemented, such as the installation of a double water circuit to pump brackish or salt water for use especially in toilets, which is already being successfully implemented in some other countries. “Legislation also needs to be improved to better define the responsibilities of bodies and organizations, because today there are many people responsible for the same issue, which does not work effectively,” concludes the professor.
Naftemporiki.gr with information from APE-MPE