Diverting water from the Caspian Sea or Sea of Oman to the drought-stricken provinces cannot curb the growing menace of land subsidence so long as extraction from underground water resources does not come to a permanent halt.
Mahdi Moateq, a faculty member at the German Research Centre for Geosciences and a lecturer in the University of Hannover, made the statement via a video conference addressing a panel on “Land Subsidence, Protection and Risks” held at Tehran’s Geological Survey and Mineral Exploration Organization, IRNA reported Sunday.
Moateq said over-extraction from renewable and underground water resources is the main culprit behind land subsidence in cities like Tehran and the northeastern regions where land on average sinks almost by 30 centimeters a year.
Conditions are deteriorating in other regions as well.
“Not long ago wells were dug 40 meters to reach water in Kerman Province for pistachio farms. Now they need to go down 350 meters, exacerbating the problem” as the water deficit spreads across the country.
Water exploitation is banned in 420 plains because water levels in these areas have plummeted by over 2 meters below the minimum level.
Overseas, subsidence in the US state of New Mexico was reported at 32cm. However, in 2010 in Tehran and later in 2015 in Fars Province the earth sank by 36cm and 54cm, respectively, to break the record.
Disturbing Decline
According to Shahpour Rajaee, head of the Water Reserves Protection Department at the Energy Ministry, the pattern of deficits in underground water resources has approached appalling levels due to the digging of unauthorized wells in banned plains.
Referring to excessive withdrawals from authorized aquifers, he said farmers are supposed to extract 36,000 cubic meters (per day), but the amount has long surpassed 50,000 cubic meters.
“The issue is so critical that Iran's Supreme National Security Council has gotten involved and stringent rules and regulations have been proposed to the government,” he said without providing details.
Agriculture policies have not been sustainable in the past 40 years because of which most underground tables have disappeared.
The National Disaster Management Organization receives reports on new cases of land subsidence on a daily basis and is worried about the growing land subsidence in transportation facilities, namely highways, airports and railroads.
“The Agriculture Ministry should have taken action to stop the disaster long ago. Now it is too late to take precautionary measures simply because most aquifers are dry or are moving in that direction.”
Water management in the agro sector is the missing link in addressing land subsidence in the country.
Rajaee says the only way to replenish dwindling water reserves is to ban water extraction from underground resources across the country including Gilan Province, which has the highest precipitation.
Consensus among experts and environment officials is that Tehran is losing the battle against land subsidence. The concern is obviously justified as the plains on the southern flank of the ever-growing capital city are shrinking by an average 30 centimeters a year.
According to the Energy Ministry, sealing illegal water wells is a key measure that also can help curb land subsidence and restore a balance to groundwater recharge. There are more than 20,000 illegal wells in Tehran Province used mostly by farmers.
