Turkey muddles through its fourth drought in fifteen years as population growth and water use skyrocket
By Charles Iceland, Claire Michailovsky, Gennadii Donchyts, Liz Saccoccia
In mid-January 2021, The Guardian reported that water was at critically low levels across Turkey as it faced the most severe drought in a decade. The truth is both a bit less dramatic and a bit more worrisome. The current drought is the fourth in less than fifteen years, and the ones in 2008 and 2014 were arguably worse. This string of droughts is part of a pattern of declining rainfall across the Mediterranean that has been observed since the early 1970s. It is also consistent with forecasts of declining rainfall across the midlatitude regions of Europe and western Asia that will result from climate change.
Precipitation records for Turkey in 2020 show much drier than average conditions throughout most of the country (Figure 1).
Lower than average precipitation throughout most of the country did not translate into uniformly lower than average evapotranspiration (ET) rates, however. Figure 2 shows ET anomalies in agricultural regions of Turkey during September – December 2020 (ET data for September to December is relevant because winter cereals are planted in September). Lower than average ET (in red) reflects crops under stress because they lack sufficient water. But there are many agricultural regions (in blue) that are doing just fine. It is possible some of the blue regions are receiving supplemental irrigation water from nearby reservoirs or from groundwater.
Lower than average precipitation throughout most of the country did not translate into uniformly lower than average NDVI rates in agricultural regions either. NDVI measures the density of green vegetation, i.e., how well crops are growing. Figure 3 shows parts of the country with lower than average NDVI and parts of the country with higher than average NDVI. Some of the regions appearing in blue may be receiving supplemental irrigation water from nearby reservoirs or groundwater.
The soil moisture anomaly map (Figure 4) is more consistent with the precipitation anomaly map (Figure 1). It shows drier than normal conditions prevailing throughout most of the country.
Now let’s examine reservoir surface areas of major reservoirs supplying Turkey’s four largest cities shown in Figure 5.
The Omerli Dam (Figure 6) is one of the main sources of water for the city of Istanbul. The time series for this reservoir shows that it was impacted more by the 2008 and 2014 droughts than by the current drought.
The Camlidere Dam (Figure 7) supplies water to Ankara. It was impacted much more by the 2008 drought than by the current drought.
The Tahtali Dam (Figure 8) supplies water to Izmir. It was impacted more by the 2018 drought than by the current drought. And it was impacted much more by the 2008 drought.
The Doganci Dam (Figure 9) supplies water to Bursa. It was impacted a little less by the 2018 drought than by the current drought. And it was impacted a bit more by the 2014 and 2008 droughts.
One way to measure the impact of the current drought is to aggregate reservoir surface areas and plot their combined change over time. Figure 10 does this for around 850 Turkish reservoirs with an area in the range of 0.01-10 km2. We have done this on the theory that these reservoirs may have an impact on large-scale water availability and that smaller reservoirs have a high socio-economic value and their evaporative losses during the dry season may amount to up to 38% of total storage. The current reduction in aggregate surface area looks more like the decline in 2014-2015 than the one in 2008-2009.
Much of Turkey faces high or extremely high levels of water stress (Figure 11). These chronic water risk conditions are made worse by periodic droughts, such as the one Turkey is now experiencing.
Turkey’s population has more than tripled from 27 million in 1960 to 83 million in 2019. Meanwhile, much of its population has moved from the countryside to cities. Turkey’s urban population surged from 32% in 1960 to 76% 2019.
The city of Istanbul grew from 3 million in 1980 to 15 million in 2021. Figure 12 shows how Istanbul’s built up area has expanded between 1975 and 2014.
To accommodate this surging population, Istanbul has increased its water storage capacity from 590 million cubic meters in 1994 to 2.1 billion in 2014. But as the above water stress map (Figure 11) makes clear, the Istanbul region is already using more water than is sustainable. That’s why every significant drought, no matter its relative size, plunges Istanbul into crisis.
But Turkey also faces a rural water crisis. While its urban water needs are rapidly increasing, it is agricultural water that accounts for the vast majority of water resource use in Turkey (as it does in nearly every other country around the world). Agriculture now accounts for nearly 85% of total water withdrawals in Turkey.
According to UN statistics, agricultural water use in Turkey increased from 23 billion cubic meters in 1992 to 50 billion in 2017. Central and northern Turkey have seen significant growth in irrigation in recent years (Figure 13).
Figure 14 shows estimated irrigation withdrawals in Turkey as of 2014.
Irrigation may be sustaining crop health and crop output in many parts of Turkey during the current drought. But irrigation is a double-edged sword. It can help sustain crops during drought. But it also tends to drive up chronic water stress levels. Most of Turkey, except for the region of the Tigris and Euphrates headwaters and some of the regions adjacent to the Black Sea, suffers from high or extremely high water stress (Figure 11).
There are many options for mitigating water-related risks to urban and agricultural security, but right now the risks in Turkey appear to be increasing more quickly than measures to mitigate these risks.
Charles Iceland (WRI) wrote the story, Claire Michailovsky (IHE-Delft) analyzed ET and NDVI anomalies for agricultural areas in Turkey, Gennadii Donchyts (Deltares) generated surface water area time series for Turkish reservoirs using Landsat and Sentinel-2 optical satellite imagery, and Liz Saccoccia (WRI) prepared data and visualizations on irrigation withdrawals.
 Some of the blue regions show low long term NDVI values suggesting that they are not used in the cultivation of winter cereals. These areas could be filtered out using more detailed crop data to give a clearer picture of the potential impact on yields of winter cereals.