Why Has Sustainable Water Supply to Istanbul Become Difficult? Is There a Risk?
Istanbul's Water Problem on the European Side The European side of Istanbul has 60% of the population and 40% of the water resources. For this reason, especially in dry periods, the partially small storage volume dams of the European side are immediately emptied. The additional water required by the European side is supplied from Melen Stream with a pumping distance of approximately 300 m from a distance of 160 km.
Istanbul has been a water transporting city throughout its history. As its population increased, Istanbul's water demand also increased and Istanbul became a difficult city in terms of sustainable water supply. This difficulty has continued until the 21st century and continues today.
In these days when the heat wave has scorched our country, the occupancy rates of drinking water dams, especially in our big cities, have come to the agenda again. Istanbul is the most curious of these cities.
The most obvious reason for this is that the sustainable supply of clean water to Istanbul has become very fragile. The reason for this fragility and the reason for the complete change in Istanbul's water supply plan is that the Melen Dam could not be put into operation due to cracks in its body. This situation creates a deficiency of approximately 700 million m3 in Istanbul's water storage volume. The water storage volume of Melen Dam alone is approximately 80% of the total storage volume of all other dams in Istanbul. In other words, the water storage capacity of Istanbul will increase 1.8 times with the Melen Dam.
The population of Istanbul and the need for drinking and utility water is increasing day by day. The Melen System has become indispensably important for Istanbul, which has received intensive migration starting from the 1990s and whose population has increased rapidly. The completion of the Melen Dam by the General Directorate of State Hydraulic Works (DSİ) as soon as possible has become of great importance both in terms of ensuring the clean water security of the city, especially on the European side, and in terms of reducing unit water costs.
Melen Dam has become the keystone of Istanbul Water Security
The Melen project, which stands out for water supply to Istanbul, consists of a dam and three large water transmission lines. The water collected in the dam is transported to Istanbul via three transmission lines. Today, approximately one third of Istanbul's drinking water comes from Melen. However, instead of being collected in the dam, the water is currently drawn directly from the Melen Stream since the dam cannot be built. The fact that the water cannot be collected in a dam and is drawn directly from the Melen Stream creates a significant electricity cost for İSKİ. In addition, the security of water supply, especially to the European side of Istanbul during dry periods, is also at risk.
Istanbul cannot withstand two consecutive years of drought
According to the assessment made by taking into account the existing water resources, Melen Dam should be put into operation as soon as possible in order for Istanbul to be less affected by the global climate change process and to reduce the vulnerability in water supply in case of drought. Because, when the dam is completed, 1 billion 77 million m3 of water will be supplied to Istanbul annually. Since Melen Dam is located 160 kilometres away from Istanbul in the Western Black Sea basin, it will also serve as Istanbul's emergency water supply insurance during dry periods.
Without the Melen Dam storage being put into operation, Istanbul's water management with the existing dams and water resources will experience great difficulties in a severe drought period of two consecutive years. Clean water supply to the city may be at risk.
Three risks to Istanbul's water supply security: Climate Change, Melen Dam, Earthquake
The three main risks to Istanbul's water supply security are climate change, Melen Dam and the expected Marmara Earthquake. Managing these three risks in a way to minimise damage to Istanbul is of vital importance for both Istanbul and our country. For this reason, the steps to be taken in this regard should be taken starting from today without wasting time. The most important of these steps is to encourage reverse migration in Istanbul. In addition, the necessary work for the management of water demand in Istanbul should be started rapidly. If the water demand in Istanbul is not managed by considering the right to water, the existing and to be developed water resources will not be sufficient for Istanbul. For this reason, sustainable management of water in Istanbul can be achieved by implementing many measures in an integrated manner and moving away from populist policies.
Istanbul's current water status as of the end of July 2023
In the city, where approximately 2.8-3 million cubic metres of water is used daily in winter, this rate increases up to 3.5 million cubic metres in summer. At the end of July 2023, the heat wave caused attention to turn to Istanbul's water reserves. According to the data on the ISKI website, as of 27 July 2023, there are 331 million m3 of water in Istanbul dams. There is 227 million m3 of water in the dams on the Anatolian side. The daily water consumption of the Anatolian side is approximately 1.2 million m3
Approximately 105 million m3 of the total water is available in the dams on the European side, of which it is estimated that 70-75 million m3 can be used when the water in the dead volume of the dam is subtracted. The daily water consumption of the European side is 2.3 million m3 .
Istanbul's Water Problem on the European Side
The European side of Istanbul has 60% of the population and 40% of the water resources. For this reason, especially in dry periods, the partially small storage volume dams of the European side are immediately emptied. The additional water required by the European side is supplied from Melen Stream with a pumping distance of approximately 300 m from a distance of 160 km. In this case, the clean water security of the European side in dry periods depends on the water to be pumped from the Melen system.
The daily amount of water that can be supplied to the European side by the Melen system is at most 1.2 million m3 . However, in July, August, September and October, the flow rate of the Melen stream is very low.
The water in the dams on the European side will be sufficient to meet the demand for only 3 months. If August, September and October of this year are dry, the clean water security of the European side of Istanbul may be at risk.
Until the Melen Dam is completed and water is stored, Istanbul's unit water cost will be high. In addition, clean water supply security will also be at risk during dry periods.
These conditions reveal that water users in Istanbul should change their water use habits and water management should take new measures according to the new conditions.
Recommendations
Reverse migration should be encouraged in Istanbul.
Istanbul's existing water basins should be protected.
Controls on sectors using excessive water in Istanbul should be increased and excessive water consumption should be restricted.
Demand management of water in Istanbul should be switched to rapidly.
Melen Dam should be completed rapidly and Istanbul's water storage volume should be increased
Social awareness should be raised for more efficient use of water in Istanbul.
