EghtesadOnline: Despite higher precipitation in October, which was 33% more compared to last year same time, average rainfall was lower than the global average. However, rainfall can be increased by cloud seeding, head of the National Cloud Seeding Research Center of Iran said.
“Average rainfall in the country usually is one third of the world. In short, Iran is always in the red zone when it comes to rains and depletion of water resources. Even when the rains are normal or above, it is still below the global average,” ISNA quoted Farid Golkar as saying.
Located in an arid and semi-arid region, Iran has suffered from drought for decades. “We must control water consumption. However, when there is more rainfall, it can be increased with the help of cloud seeding,” Financial Tribune quoted him as saying.
Cloud seeding, a form of weather modification, is a way of attempting to change the amount or type of precipitation by dispersing substances into the air, which serve as cloud condensation or ice nuclei, and alter the cloud's microphysical processes.
According to official data, cloud seeding projects have been undertaken since 2008 in several provinces namely Tehran, East and West Azarbaijan, Gilan and Mazandaran.
Unlike the common belief that cloud seeding means rainfall, “it can only raise the amount of rain,” Golkar noted.
The system cannot function when there is no rain. The project was not carried out last year, as it was one of the driest years in 70 years.
“The main purpose of the projects was to address the drought and water crisis,” the NCSRC boss said.
Since it is not possible to forecast how much rain will fall in the coming years, he added: “This year we had abundant rains and it is better to resort to cloud seeding to increase precipitation and save water for the coming years”.
He hoped that the project will start by the end of fall.
Cloud seeding is done with the use of planes, drones and ground-based generators.
The chemicals needed for the project can also be spread by aircraft or drones or by dispersion devices on the ground (generators). For release by aircraft, silver iodide flares are ignited and dispersed as an aircraft or drone flies through a cloud.
When released by ground devices, the fine particles are carried upwards by air currents after release.
When water vapor or droplets join the silver iodide crystal, latent heat is also released, and it increases cloud size and the duration of storms.
Regarding sites where the project will be implemented, Golkar said: "The focus is on watershed where there are dams that provide more space for water storage. There are also sites like plains and rangelands with no dams around but for which rainfall is equally important, such as regions in South Khorasan Province. We are planning to cover these areas.”
According to Golkar, despite the fact that cloud seeding can increase rainfall, the scope is limited and cannot exceed more than 140 kilometers.
"Put simply, it is impossible to increase precipitation all over the country with the help of this technology. In the best case scenario it might work in a limited region."