Excessive water extraction from agricultural wells has caused land subsidence in many Iranian plains, leading to the decline in the quality and volume of drinking water and the evacuation of some rural areas, the spokesperson of Majlis Agriculture, Water and Natural Resources Commission said.
“Land subsidence has occurred in about 500 plains out of 609 plains in Iran and the government should restrict the cultivation of water-intensive crops and non-strategic products,” Zabihollah Azami Sardoui was also quoted as saying by the Energy Ministry’s news portal.
Land subsidence is defined as a gradual or sudden sinking of the earth's surface owing to subsurface movement of earth materials.
In addition to injudicious groundwater extraction, other causes of land subsidence are aquifer-system compaction, drainage of organic soils, underground mining, hydro-compaction, earthquake and gas and oil extraction.
Disorganized urbanization, old and obsolete farming practices and the presence of water-intensive industries in different regions are exacerbating the rapidly dwindling water reserves.
The steep decline in groundwater levels is having devastating consequences. Excessive pumping is harming groundwater tables and stopping wells from reaching groundwater. When groundwater is overused, lakes, streams and rivers connected to groundwater also start diminishing.
The problem has evolved over a long time and cannot be addressed overnight, but short-term measures are expected to help improve present conditions and prevent the expansion of land subsidence.
Referring to farming practices that consume huge amounts of water, Azami said it is necessary to stop planting non-strategic products such as watermelon and start importing them to preserve the water resources for the cultivation of major strategic products.
Water-Intensive Crop
Referring to rice as a water-intensive crop currently cultivated in 19 provinces, he said, “Despite the restrictions imposed by the parliament on planting rice in certain arid and semi-arid regions, hundreds of hectares of farmlands have been allocated to rice cultivation.”
Agricultural and environment experts have been urging the government for years to restrict rice farming to water-rich provinces and to ban its cultivation in the rest of the country.
According to the official, issuing permits for digging legal water wells without considering a region’s condition and the presence of illegal wells has reduced groundwater levels and triggered land subsidence.
In Iran, the population has more than doubled in the past 50 years, while groundwater pumping remains unregulated. The country’s cities are now among the fastest-sinking urban centers in the world, descending by up to 25 cm each year.
Many provinces, including Hamedan, Markazi, Tehran, Qazvin, Isfahan, Fars, Kerman, Sistan-Baluchestan, Hormozgan as well as South and North Khorasan and Khorasan Razavi, are severely grappling with the phenomenon.
Reportedly, Fars Province has the worst condition of all, since almost all wetlands and lakes have dried up, causing an annual 54 cm of land subsidence.
Another alarming situation have been witnessed in the 36-cm subsidence in Moeinabad and the 25-cm sinking of Varamin in southern Tehran. The land has sunk by 20 cm in Tous Plain of Khorasan Razavi Province.
