Dry river bed near the Latyan Dam, one of the main water sources in Tehran, Iran.
BAKHRAM/Middle East Images/AFP via Getty Images
Iran is experiencing such a severe drought that the country's president has said the capital Tehran may have to be evacuated. In an attempt to bring rain, the planes began a cloud seeding operation on November 15 that is planned to continue through the traditional rainy season until May. But experts warn that the method is complex and unlikely to make a significant impact on the water crisis on its own.
How bad is the drought in Iran?
Rainfall in Iran is 85 percent below average, and Tehran has received just 1 millimeter of rain this year. Reservoirs in the capital and surrounding regions are in an “alarming state,” with water capacity at 32 dams at less than 5 percent, officials said. Satellite images disclose some are completely dry.
Tehran residents have reportedly cut their water consumption by about 10 percent, but that is not enough, officials say. Water pressure drops at night, and authorities plan to fine households and businesses that use excessive amounts of water. If rainfall does not increase by December, the 14 million people living in Tehran may have to begin evacuating, the president said.
What caused the drought?
Experts say The climate crisis has contributed to a drought that has now lasted five years. Iran is experiencing its driest autumn in 50 years, with temperatures reaching 15°C (59°F) and above in Tehran, where it often snows in November.
But poor management is the main reason why Kaveh Madani, a former environment ministry official calls Iran a “water bankruptcy.” The government has greatly expanded agriculture in dry areas, excessively depleting water resources. Half a million illegal boreholes, many drilled by desperate farmers, have depleted groundwater.
What is cloud seeding?
Cloud seeding was developed in the 1940s by scientists including Bernard Vonnegut, brother of writer Kurt Vonnegut. It involves the dispersal of particles that cause suspended water droplets in clouds to fall as rain. Although some projects sprayed salt into low-lying clouds, many focused on spreading chemicals, most commonly silver iodide, into higher mixed-phase clouds. Supercooled drops of liquid water freeze on contact with this crystalline compound, forming ice crystals that become heavy and fall as snow or rain.
However, it is often difficult to predict how much rain or snowfall would fall without cloud seeding.
“The effects are very difficult to demonstrate due to the large natural variability of clouds,” says Andrea Flossmann at the University of Clermont Auvergne in France. “You look outside, you have a cloud field, and there are clouds that rain and others that don’t.”
A 2014 experiment comparing two mountain ranges in Wyoming found that cloud seeding could increase precipitation by from 5 to 15 percent.
Could this solve the drought problem?
Iran, which previously accused Israel and the United Arab Emirates of stealing rain through cloud seeding, now has its own program that includes spreading seeding agents from cargo planes, drones and “earth generators”a term that usually refers to smoke stoves in the high mountains.
On November 15, he said, they sowed clouds in the basin around Lake Urmia, which in two decades had dried up and turned into a salt flat dotted with rusty boats. Early the next morning, up to 2.7 cm of rain fell in areas west of the lake, the agency said. precipitation map under the direction of the University of California, Irvine.
However, to conduct a cloud seeding campaign to replenish water bodies, the clouds must contain a lot of water. Such a cloud might be difficult to find in arid Iran, where there are few large bodies of water capable of evaporating moisture into the air.
“During droughts, cloud seeding is often much more difficult because the atmosphere is very dry, and any clouds present may not have enough moisture,” says Karen Howard, a scientist at the U.S. Government Accountability Office.
However, over the past three days, masses of rain clouds have flown into Iran from the Black Sea, even causing flooding in the western provinces, including Ilam and Kurdistan, on November 16.
Cloud seeding could at least “squeeze a few more drops” out of such weather systems, says Armin Sorushyan at the University of Arizona. “It won't lead to extreme events like flooding or addressing widespread drought,” he says. “But this might help a little.”
Topics:
