Filenews 5 March 2024 - by Angelos Nicolaou
Ten aging dams face safety problems and have been put under the microscope of the Water Development Department (WDD). Dams that, if no action is taken, will result in the destruction of property and even the loss of lives.
In a WDD report, revealed today by "F", reference is made to the dams that need immediate priority due to the safety problems they present and which were grouped into three categories: a) Built near residential areas, b) they present mechanical problems and c) they cause an impact on the country's economy.
These dams are Polemidia, Tamassos, Xyliatos and Evretos due to the proximity to residential areas, Germasogeia, Lefkara, Dipotamos and Kalavasos with serious problems in mechanical equipment and the current situation being characterized as dangerous and the dams Kouris and Asprokremmos, the two largest in capacity in Cyprus, where any damage the impact on the country's economy will be incalculable.
Aiming at the safety and maintenance of dams, the largest number of which have exceeded 50 years of useful life, the Ministry of Agriculture, Rural Development and Environment proceeds with specific actions. Actions to be implemented to ensure the proper and safe operation of the large elevated reservoirs of Cyprus and fall under the legislation on integrated water management law. The dams that require systematic monitoring and safety assessment amount to 104 and have a capacity of more than 25,000 cubic meters.
In the first group, of high-risk dams adjacent to residential areas, reference is made to the Polemidion damlocated on the upper side of the city of Limassol, the dam of Tamassos constructed on the upper side of Nicosia, as well as the dam of Evretos where landslides of surface soils occurred in the past after the raising of the reservoir level.
The Polemidia dam, one of the oldest large dams in Cyprus, was built in 1965 with a capacity of 3,864,000 cubic meters and is located upstream of the city of Limassol. It is no coincidence, therefore, that in the ranking of the degree of risk it is in the first places as upstream of the dam there is intense residential development. Therefore, in addition to water storage, this dam also acts as a flood protection system. Since the dam was constructed in 1965, its electromechanical equipment has deteriorated, with the bottom evacuator inactivated. The issue is considered very serious since the dam cannot be evacuated in case of emergency.
According to the supervising engineer, as recorded in the WDD report, "the Polemidia dam, apart from storing water for irrigation, plays a very important flood protection role. This is because it is located upstream of a densely populated area which, due to the presence of the dam for many years, has not experienced flood flow. As a result of legal or illegal interventions in the riverbed downstream of the dam, the passage of water has been restricted and under the present conditions it is practically impossible for it to be able to receive significant flooding. This will result in the destruction of property and loss of life. The increase in extreme weather events is a fact and there is no question of whether there will be a flood flow in the Garyllis River but when there will be. Based on Cyprus' obligation to take measures to limit the consequences of flooding, it is proposed to install a tipper window system that can temporarily store a quantity of water from flood flows.
In the same category is the dam of Tamassos with construction year 2002 and a capacity of 2,800,000 cubic meters. The dam of Tamassos ranks among the first three dams with the highest risk. The main parameter that ranks it so high is the fact that it is constructed upstream of the city of Nicosia. During the design / construction stage, an old landslide was detected on the left slope of the flood basin. Part of the spillway is founded on clay soils, which has given differential movements. The WDD, recognizing the importance of this dam, had prepared in 2008, in collaboration with Consulting Engineers, studies for the effects after a possible failure or flood.
The Xyliatos dam was built in 1982 and today has a capacity of 1,430,000 cubic meters. It had an initial capacity of 1,220,000 cubic meters, which was increased in 1998 with the installation of gates on the spillway. It is located in a beautiful, green area in the forest, which in combination with its frequent overflow, classifies it among the most visited dams. At the downstream foot of the dam, next to the point of overflow, there is an organized picnic area. Significant losses occur from the walls of the discharge/abstraction tunnel, which end up downstream. The most important problem of the dam concerns its electromechanical equipment, specifically the hydraulic discharge system, which does not work. The discharge valve is located at the bottom of the discharge tunnel, so it is not possible to open it manually, except remotely via the hydraulic system – which does not work.
The dam of Evretos built in 1986 has a capacity of 25,000,000 cubic meters and is the main storage body of the Chrysochous irrigation project. It has many peculiarities, as it is not an ordinary conventional barrier. Upstream of the reservoir, near the entrance to the discharge tunnel, surface soil landslides occurred in 1987 and 1988, following the rise of the reservoir level. Due to these particularities, the dam of Evretos is classified in the first places of the dams with high risk.
Dams requiring immediate priority due to problems and impact on the economy
Three dams fall into the category of those with mechanical problems,Germasogeia, Lefkara and Dipotamos, while another two are considered important due to the impact on the country's economy, Kouris and Asprokremmos.
The Germasogeia dam was constructed in 1968 and has a capacity of 13,600,000 cubic meters. It is located upstream of the residential area of Germasogeia and the Nicosia – Limassol motorway. Given the residential development downstream of the dam and the interventions that have been made within the riverbed, as in the case of the Polemidia dam, the dam partially acts as a flood protection system. For the same reasons, its proper and safe operation is of particular value.
The dam of Lefkara was constructed in 1973 and has a capacity of 13,850,000 cubic meters and is used for both irrigation and water supply purposes. It has never overflowed, as its catchment area is small in relation to the capacity of its reservoir. At the dam, serious problems are found in the pipelines and electromechanical equipment, which due to their non-maintenance for years worsen with the passage of time, while their current condition is characterized as dangerous.
The Dipotamos dam was constructed in 1985 and has a capacity of 15,500,000 cubic meters. In 1998, a system of gates was installed at the dam on the spillway to increase its capacity. The main problems of the dam concern the maintenance and operation of electromechanical equipment.
The Kalavasos dam was constructed in 1985 and has a capacity of 17,000,000 cubic meters and is similar in construction to that of Dipotamos, as they are both part of the Vasilikos – Pentaschoinos project.
The Kouris dam was constructed in 1988, has a capacity of 115,000,000 cubic meters and is the largest dam in Cyprus. Its capacity is about 1/3 of the total capacity of all dams. After the first overflow of the dam, in 2004, additional waterproofing works (cement grouts) were carried out on the right buttress, which, according to the measurements taken, significantly reduced the losses.
It is noted that any damage to the Kouris dam will have economic consequences, due to the impact on the country's water supply.
The Asprokremmos dam was constructed in 1982 and has a capacity of 51,000,000 cubic meters. Asprokremmos is the second largest dam in capacity after Kouris and is the main source of water supply in Pafos.
