The average annual precipitation in southern Sistan and Baluchestan Province has decreased by 50 percent over a 40-year period, states a report by the National Drought Warning and Monitoring Center (NDWMC).
In the short-term too, the level of rainfall in Sistan and Baluchestan decreased to 27.6% in the first three quarters of the current calendar year (ends March 20), from 82.3% in the corresponding period of the previous year, said Doust-Mohammad Kalim, chairman of the Applied Metrology Research Group of the Metrological Organization of Sistan and Baluchestan Province.
Khash received the ‘highest’ rainfall recording only 22.9 mm, showing a steep 85% decline compared to the previous year (151.1 mm), Iran newspaper reported.
According to the Metrological Organization of Iran (MOI), the average precipitation level in the country is 225 mm, with the highest level of rainfall recorded in the north (1000 mm) and the least in the southern parts of the country (less than 5mm). In autumn, Roudsar in the northern province of Gilan recorded 1,095 mm of rainfall, while Zehak in Sistan and Baluchestan recorded less than 4 mm.
Other Provinces
In the first quarter of the current water year (started September 23) the amount of rainfall in 20 provinces showed a decline over a four-decade period, the report said; however, it only pointed to the 28% and 26% of precipitation decrease in South Khorasan and Qom provinces respectively, without providing figures for the other provinces.
The NDWMC report confirms the earlier warning by the Water Resources Management Company of Iran about low precipitation in 20 provinces. It also anticipated that the decrease in precipitation will continue till the end of winter.
Hamideh Habibi, an official at the Kerman Metrological Organization said the amount of rainfall in the province has generally decreased, with regions like Shahdad, Rigan, and Roudbar-e Jonubi having no rainfall at all. The rainy season in Kerman Province starts on January 21 and lasts till April 20.
For the southern province of Hormozgan, the MOI said the water year saw 47.4 mm rainfall in the province, showing a 45% decline compared to the previous year.
Weather Systems
Low precipitation in Sistan and Baluchestan Province goes back to the weak performance of weather systems that bring rain to the region, say experts.
“In the summer, monsoon and tropical low-pressure weather systems create seasonal changes in atmospheric circulation in the southeast region, especially Sistan and Baluchestan Province,” Kalim said, adding that the systems “were weak in recent years.” Mediterranean weather systems also get weak as they move from West to East of the country.
