It was the river that is said to have watered the biblical Garden of Eden and helped give birth to civilisation itself.
The Tigris’s course through Iraq begins in the mountains of northern Iraq’s Kurdish region, near the borders of Turkey and Syria, where local people raise sheep and grow potatoes.
But today the Tigris is dying.
Human activity and climate change have choked its once mighty flow through Iraq, where, with its twin river the Euphrates, it made Mesopotamia a cradle of civilisation thousands of years ago.
Iraq may be oil rich but the country is plagued by poverty after decades of war and by droughts and desertification.
From April onwards, temperatures exceed 35˚C (95˚F) and intense sandstorms often turn the sky orange, covering the country in dust.
Hellish summers see the mercury top a blistering 50˚C (122˚F), near the limit of human endurance, with frequent power cuts shutting down air conditioning for millions.
The Tigris, the lifeline connecting the storied cities of Mosul, Baghdad and Basra, has been choked by dams, most of them upstream in Turkey, and falling rainfall.
The level of the Tigris entering Iraq has dropped to just 35% of its average over the past century.
All that is left of the river Diyala, a tributary that meets the Tigris near the capital Baghdad, in the central plains, are puddles of stagnant water dotting its parched bed.
Drought has dried up the watercourse that is crucial to the region’s agriculture.
This year authorities have been forced to reduce Iraq’s cultivated areas by half, meaning no crops will be grown in the badly-hit Diyala governorate.
The International Organization for Migration said last month that “climate factors” had displaced more than 3,300 families in Iraq’s central and southern areas in the first three months of this year.
Years of war have destroyed much of Iraq’s water infrastructure, with many cities, factories, farms and even hospitals left to dump their waste straight into the river.
Salt water from the Gulf is pushing ever further upstream as the river flow declines.
The United Nations and local farmers say rising salination is already hitting farm yields, in a trend set to worsen as global warming raises sea levels.
Last month local authorities reported that salt levels in the river north of Basra reached 6,800 parts per million, nearly seven times that of fresh water.