Cartoon by Maarten Wolterink

Iran water: What's causing the shortages?

BBC: Protests in Iran against a range of grievances - including a severe lack of water and power blackouts - have drawn attention to the country's wider water problems.

Experts have raised concerns about the situation for many years, so what's to blame for Iran's water crisis?

A very dry year

In April, the Iranian Meteorological Organisation warned of an "unprecedented drought" and rainfall levels which were substantially below long-term averages.

In the oil-producing province of Khuzestan, residents took to the streets over water shortages, and there were protests against hydroelectric power cuts in other cities.

The government has responded with emergency assistance for the hardest-hit areas.

Iran faces a range of environmental challenges from high temperatures, pollution, flooding and vanishing lakes.

The amount of rainfall in Iran's main river basins between September 2020 and July 2021 was, in most places, substantially lower compared to the same period last year, according to data from the Ministry of Energy's website.

We haven't been able to access government figures for historical trends, but researchers in the United States have gathered data using satellite imagery.

This data compares rainfall up to March of this year against the 40-year average. The first three months of 2021 were all well below that average, according to the Center for Hydrometeorology at the University of California Irvine.

The UN's Food and Agriculture Organisation has estimated about one-third of valuable wheat fields in Iran are irrigated, so no rain can be costly.

What's happened in Khuzestan?

Amid a very dry spell in the province, locals have been out protesting - some shouting "I am thirsty!"

For a region which used to have plentiful water, the vital Karun river now often runs dry.

Satellites show its water level has steadily fallen over the last year, according to data gathered by researchers at Stuttgart University.

The spike in 2019 was due to severe flooding.

A map sourced to authorities in Khuzestan shows water levels in the region's dams in July 2021. The light blue line indicates the water level.

Many of the critical dams currently appear to be running low, and there have been calls for the release of remaining water to support rice and cattle farmers in the regions below them >>>