Drought · North-western Türkiye
The winter Istanbul nearly ran dry
In early January 2021 Istanbul's reservoirs, which supply sixteen million people, fell to their lowest level in fifteen years: 19 % of capacity on 8 January. Two dry years had come one after the other, and the autumn rains that usually refill the lakes of Thrace had largely failed. Then, in the second half of January, the rain came back.
Autumn 2020 – January 2021 · Istanbul and Thrace, Türkiye · ERA5
160mm
ERA5 at Istanbul, Sep–Dec 2020
Against a 1991–2020 normal of 317 mm for those four months.
615mm
Istanbul's rain in 2020
ERA5: the third driest year of 1991–2020, after an almost as dry 2019 (625 mm). The normal is 750 mm.
What happened
Istanbul draws most of its water from reservoirs in Thrace and on the Asian side, filled by winter rain. 2019 had been dry, and 2020 drier still. The autumn of 2020 was the decisive failure: September brought almost nothing, and November and December, usually the wettest months, gave Istanbul about half their normal rain.
By the first days of January the reservoirs were at a fifteen-year low and the city's water utility was urging people to save water.N1 The drought was not Istanbul's alone: much of western and central Türkiye was short of rain that winter.N3 Heavy rain and snow from mid-January then refilled them: within weeks the fill rate was back above 40 %.N2
An autumn without rain
| Month | 2020 | Normal 1991–2020 |
|---|---|---|
| September | 14 | 53 |
| October | 71 | 80 |
| November | 38 | 78 |
| December | 37 | 106 |
| Sep–Dec | 160 | 317 |
Dry ground
Rain on dry soil soaks in before it runs off to the reservoirs. ERA5's soil moisture shows how little water the ground of the Marmara region held at the start of winter in both years, so that even the rain that fell did little for the lakes.
Thirty years of rain
−15mm per decade
The trend in ERA5's annual rain at Istanbul over 1991–2020, small against the year-to-year swings. Dry years like 2019 and 2020 come and go; two in a row is what empties the reservoirs.
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References
News
- N1Turkish Minute. Water level in reservoirs supplying Istanbul drops to 15-year low, raising drought concerns. 5 January 2021.Istanbul's reservoirs at a fifteen-year low in early January 2021.
- N2Bianet (Anadolu Agency). Fill rate of Istanbul's dams is now over 40 percent. January 2021.The fill rate of 19 % on 8 January and the recovery after it.
- N3NASA Earth Observatory. Turkey experiences intense drought. January 2021.The drought across Türkiye in the winter of 2020–21.