The water level in Tehran dams has decreased significantly. At present, water inflow into the dams is 200 million cubic meters which indicates a 16% decline compared to the previous water year (starts October 1), said Rahim Meidani, deputy minister of energy for water and wastewater affairs.
In the current year, the total snowfall received in various parts of the country had also declined by 77% compared to the previous year; however precipitation in some catchment areas had seen a rise; for instance in the Caspian Sea it had increased by 34%.
But precipitation in the catchment areas of the Persian Gulf and Oman Sea decreased by 42% and the rainfall rate dropped by 28% in the Central Plateau, the official said. Precipitation was favorable in Lake Urumia’s catchment area in this water year and the water level of the lake had increased significantly after 18 consecutive years of drought.
Important Dams
The most important dams built on the rivers running though Tehran Province include Amir Kabir Dam, Lar Dam and Latiyan Dam. Amir Kabir Dam (or Karaj Dam), a multi-functional dam, was built in 1961 in the northwest of Tehran on Karaj-Chaloos road. Its watershed area is 764 sq km, with an average annual water of 472 million cubic meters.
The dam was built to control spring torrents, prevent damage from floods and to supply Tehran’s drinking water by 340 million cubic meters per year as well as to provide water for farm lands surrounding Karaj by 130 million cubic meters per year. Generating energy to help the nationwide electricity network, especially during peak hours, by providing 150 megawatt per hour per year was another objective.
Latiyan Dam in northeast Tehran is 5 kilometers off Jajrood with a watershed area of 69,800 sq km, and average annual water supply of 350 million cubic meters. The dam was constructed to supply Tehran’s drinking water by 290 million cubic meters per year, and to provide 160 million cubic meters per year for agricultural purposes at Varamin plain. The Kalan power house is 20 kilometers off the dam.
From 1989, 140 million cubic meters of Lar water is being transferred along a 20-km route to Kalan power house and then on to Latiyan dam. As a result, the Latiyan Dam water saw an increase by 410 million cubic meters. Another supplier of drinking water to Tehran is Lar Dam built in 1982 on the river Lar, 70 km northeast of Tehran in Mazandaran province, with a watershed area of 675 sq km, and an average annual water reserve of 481 million cubic meters.
The primary purpose of the dam is municipal water supply to Tehran but prior to the water reaching the city filtration plant it is used to power the Kalan and Lavarak Hydroelectric Power Stations, with a combined installed capacity of 162.5 MW.
Cloud Seeding
This year (ends March 20) $2.85 million has been sought for implementation of cloud seeding and currently the operations have been executed in 6 provinces including East Azarbaijan, Kerman, Yazd, Isfahan, Fars and Chaharmahal and Bakhtiari, said Meidani, quoted by Alef News Agency.
The operation is expected to be implemented in 12 provinces besides the above-mentioned provinces and also includes West Azarbaijan, Kohgiluyeh and Boyer Ahmad, Tehran, Gilan, Alborz and Mazandaran Provinces. Cloud seeding will be undertaken in Gilan and Mazandaran Provinces in May.
Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud.
The average effectiveness of cloud seeding is 10 to 15 % but according to the latest reports from the six provinces, the operations have been effective, Meidani said. “The project has not been implemented in Tehran yet, since the clouds should be capable of seeding and have a thickness of at least 5 kilometers.”
