40% Decline in Precipitation

Rainfall in Iran's six main catchment areas has plunged 40% since the beginning of the current water year in Sept. 2020.
The Iran Water Resource Management Company said 157 millimeters of rain (155 billion cubic meters) fell in the last 147 days, down 40% compared to the same period last year, the Energy Ministry news portal reported.
Iran is divided into six primary and 31 secondary catchment areas. The six major basins are Central Plateau in Markazi Province, Urmia Lake in the northwest, Persian Gulf and Sea of Oman in the south, Hamoun Wetlands in the east, Karakum basin in the northeast and Caspian Sea in the north.
As usual the Caspian Sea in the north logged the highest precipitation at 178 mm but still was 18% lower than the year before when 217 mm of rain fell in the scenic and major tourist region.
Although the Persian Gulf and Sea of Oman basin received 269 mm of rainfall in the period (147 days) in 2020, it declined to 158 mm in 2021, down 41%.
Karakum basin in the northeast had 52 mm of rain -- down 48% compared to the previous year.
Likewise, close to 52 mm of rainfall was registered in the Central Plateau in Markazi Province, less 49% compared to a year ago. The least amount of rain (15 mm) fell in the Hamoun Wetlands in the east, down 82% compared to 2020. 
Urmia Lake basin in the northwest received more rain. With 138 mm, it was 16% higher in the 147 days compared to 2020 when 119 mm of rainfall was recorded.