EghtesadOnline: Iran registered 293 millimeters of rainfall since the beginning of the current water year in September. Precipitation in nearly 7 months rose 200% compared to the same period last year, and 65% over and above the annual average registered over the past half century.
The 2017-18 water year, which was the driest in the past 50 years, caused many reservoirs and wetlands to dry up and ground water to deplete accelerating land subsidence in many regions. If this pattern continues Iran will face serious challenges regarding access to water for drinking and industrial and farming needs, IRNA reported.
Since March 19 heavy rains unleashed flash floods across the country, especially in the north, west and southwest.
More rain has been forecast for the next two weeks in the west and southwest, according to Financial Tribune.
According to official reports, rainfall is expected to intensify in the southwestern province of Khuzestan and western Lorestan Province.
The long-awaited downpours killed at least 80 people and caused immense loss to life and limb, but at the same time it made some say that the drought was finally a thing of the past and that the country had entered a wet spell.
People including Mohammad Darvish, a member of Research Institute of Forests and Rangelands, Ahmad Qandehari, an official at the Regional Water Company of Khorasan Razavi, and Ahmad Sadeqi, former head of Tehran Disaster Mitigation and Management Organization had announced that Iran had entered a wet year.
Parviz Kardavani, renowned geographer and environmentalist, however, rejects such presumptions and insists that global warming is the primary reason for the heavy rains in Iran unseen over 60 plus years.
“It is simply not true that we have entered a wet year,” he said. “Due to global warming, drought has affected many parts of the world including Iran. This could continue for many more years”.
The warming of the Earth has led to both droughts and floods, the expert noted, saying that climate change is driving both wet and dry extremes. In areas with low precipitation rainfall has decreased and areas with higher precipitation have seen heavy downpours.
The Earth is warming because humans are emitting heat-trapping greenhouse gases. It is a well-known scientific principle that warmer air holds more water vapor. The amount of moisture that can be held in air grows very rapidly as temperatures rise.
So it is expected that air will get moister as the Earth warms – provided there is a moisture source. This may cause more intense rainfall and snowfall and increased risks of flooding.
But warmer air can also more quickly evaporate water from surfaces. This means that areas without precipitation dry out more quickly. So while global warming can cause flooding in some regions, it can lead to drought in others.
It is also likely that some regions will experience both more drought and more flooding in the future (not necessarily at the same time). The dry spells are longer and with faster evaporation causing dryness in soils.
But, when the rains fall, they come in heavy downpours potentially leading to more floods. The floods in California in February – which followed a very intense and prolonged drought – is a vivid example.
This also explains the heavy rainfall and flash floods in Iran that began last month, overflowing rivers, washing away bridges, inundating houses and destroying infrastructure. The heavy downpour was unprecedented over six decades during which most regions reported heavy declines in rainfall.
“Rainfall in Iran has been less than one-third of the global figures during the past decades. Something like 250 mm of rain fell and drought hit the country gradually,” Kardavani noted.
If and when the current precipitation pattern continues for two to three years, after that it could be said that the country is going through wet years, he was quoted as saying by the state news agency.
Although higher precipitation will reduce water tension Iran has been suffering for more than a decade, the three week plus deluge has already killed 80 people and inflicted colossal human and material damage in several towns and villages, especially in the western and northern regions.
Floods have caused an estimated $2.5 billion in damage to roads, bridges, homes, infrastructures and agricultural land.
Over 260 cities and 5,000 villages in 25 provinces have been affected. More than 220,000 people are forced to stay in emergency shelters. 14,000 kilometers of road have been damaged and more than 700 bridges completely destroyed by landslides and flood water.