Anthropogenic depletion of Iran’s aquifers

Abstract

Global groundwater assessments rank Iran among countries with the highest groundwater depletion rate using coarse spatial scales that hinder detection of regional imbalances between renewable groundwater supply and human withdrawals. Herein, we use in situ data from 12,230 piezometers, 14,856 observation wells, and groundwater extraction points to provide ground-based evidence about Iran’s widespread groundwater depletion and salinity problems. While the number of groundwater extraction points increased by 84.9% from 546,000 in 2002 to over a million in 2015, the annual groundwater withdrawal decreased by 18% (from 74.6 to 61.3 km3/y) primarily due to physical limits to fresh groundwater resources (i.e., depletion and/or salinization). On average, withdrawing 5.4 km3/y of nonrenewable water caused groundwater tables to decline 10 to 100 cm/y in different regions, averaging 49 cm/y across the country. This caused elevated annual average electrical conductivity (EC) of groundwater in vast arid/semiarid areas of central and eastern Iran (16 out of 30 subbasins), indicating “very high salinity hazard” for irrigation water. The annual average EC values were generally lower in the wetter northern and western regions, where groundwater EC improvements were detected in rare cases. Our results based on high-resolution groundwater measurements reveal alarming water security threats associated with declining fresh groundwater quantity and quality due to many years of unsustainable use. Our analysis offers insights into the environmental implications and limitations of water-intensive development plans that other water-scarce countries might adopt.

Iran's Groundwater Hydrochemistry

“…Vahidipour et al (2021) concluded that the saltwater intrusion from the Bakhtegan Lake could threaten the groundwater resources in its coastal aquifers. Other studies also suggest the saltwater intrusion is a main contributor of groundwater degradation in different parts of Iran (e.g., Ebrahimi et al, 2016;Gorgij and Moghaddam, 2016;Bahrami Jovein and Hosseini, 2017;Ranjbar and Mahjouri, 2018;Noori et al, 2021).…”

“…This is particularly true for the irrigation needs in Mediterranean climate regions, where the high irrigation water demands overlap with the dry season. As a consequence, Iran's agricultural expansion resulted in nonrenewable water harvesting due to the digging of a large number of deep and semi-deep wells (~750,000 wells), leading to a catastrophic decline in groundwater levels across the country (Maghrebi et al, 2020;Noori et al, 2021). The overexploitation of groundwater has deteriorated the IGWR through salt-rich water intrusion induced by non-equilibrium hydraulic gradient between fresh and saline groundwater resources (Ebrahimi et al, 2016;Motallebian et al, 2019).…”

“…In addition, our investigation indicated that the measured EC data were strongly correlated with the corresponding TDS, boosting confidence in the groundwater quality data. Detailed information on the different sources of uncertainty as well as quality control/assurance procedures on the groundwater data is given by Noori et al (2021).…”

“…Easy access, reliability, inexpensive energy, and insufficient supervision have resulted in a growing number of authorized and unauthorized groundwater extraction points, leading to national worries over the consequences for water quality (Nasrabadi and Maedeh, 2014;Mirzavand and Bagheri, 2020a;Rezaei et al, 2020). Noori et al (2021) concluded that the number of groundwater extraction nodes (e.g., wells, qanats and springs) increased from about 546,000 to over a million only during a 14-year period starting from 2002. Also, according to the official reports issued by the Iranian Parliament Research Center (IPRC, 2017), about 5 km 3 out of the 50 km 3 of groundwater extracted annually comes from non-renewable groundwater sources.…”

“…Also, according to the official reports issued by the Iranian Parliament Research Center (IPRC, 2017), about 5 km 3 out of the 50 km 3 of groundwater extracted annually comes from non-renewable groundwater sources. Such over extractions have led to: a) An alarming pressure on Iran's groundwater resources (IGWR), causing a severe and widespread decline in water levels across the country of about 50 cm yr -1 during the last two decades (Noori et al, 2021), b) Socio-physical crises such as population displacement (Madani et al, 2016;Danaei et al, 2019;Panahi et al, 2020) and unprecedented/extensive land subsidence (Motagh et al, 2008), c) Fundamental environmental challenges such as saltwater intrusion and groundwater quality deterioration (Ebrahimi et al, 2016;Madani et al, 2016;Kardan Moghaddam et al, 2017;Motevalli et al, 2018;Vesali Naseh et al, 2018;Noori et al, 2019a).…”