Turkey, the upstream country, began filling the Ilisu dam a year ago. Tigris river levels at the Iraq-Turkey border have halved, say water experts.
"The water level on the Tigris River was around 600 cubic metres per second. But after the building of Ilisu system (dam) it became around 300 to 320 cubic metres per second," says Ramadan Hamza, a senior expert on water strategies and policies in the University of Dohuk.
Hamza says this risks leading to drought in Dohuk, Mosul, Salahaddin, Baghdad and al-Kut.
Hezha Abdulwahed, the director of the water department in Dohuk, notes that river levels have fallen despite an increase in rainfall.
"There is a huge difference (in water levels) and the drop is about 8 billion cubic metres of water in April and May compared to the same periods last year," he says.
The Ilusu dam has the capacity to store 10 billion cubic metres in its reservoir, according to Abdulwahed.
If Iraq fails to negotiate with Turkey over its share of the river, the upstream country will have full control of the Tigris by 2022, Hamza adds.
Turkey has also built dams along the Euphrates river, heavily impacting downstream Syria. The Kurdish-led authorities in northeast Syria have accused Ankara of deliberately withholding water from the areas it controls, as have international human rights organisations.
