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Land Subsidence: A Silent Crisis Threatening Iran

Understanding the Causes, Global Experiences, and Potential Solutions

Introduction: What is Land Subsidence?

Land subsidence refers to the gradual or sudden sinking of the Earth’s surface due to natural or human-induced factors. This phenomenon can lead to significant environmental, infrastructural, and economic consequences. It occurs when underground materials, such as water, oil, or gas, are removed, causing the land above to sink.

Key Causes of Land Subsidence:

• Excessive Groundwater Extraction: The primary cause worldwide. When groundwater is withdrawn faster than it can be naturally replenished, the soil structure collapses, leading to subsidence.
• Mining Activities: The removal of minerals, coal, or other underground resources weakens the Earth’s surface.
• Natural Sediment Compaction: Over time, sediments naturally settle and compact, leading to gradual land sinking.
• Oil and Gas Extraction: The removal of subsurface fluids reduces pressure, causing land to collapse.
• Seismic and Tectonic Activity: Earthquakes and geological movements contribute to sudden subsidence in some regions.

Why Land Subsidence is a Serious Concern:

• Infrastructure Damage: Roads, buildings, bridges, and pipelines can crack or collapse.
• Increased Flooding Risk: Lowered land elevation makes areas more prone to water accumulation.
• Loss of Agricultural Productivity: Subsidence can disrupt irrigation systems and degrade soil quality.
• Environmental Degradation: Changes in topography can alter ecosystems and reduce biodiversity.

Example: In Jakarta, Indonesia, parts of the city have sunk by 4 meters in the past 50 years, leading to frequent floods and the relocation of entire communities. Without intervention, Jakarta may become uninhabitable by 2050.

Global Experiences with Land Subsidence

1. Mexico City, Mexico

• Issue: Mexico City has sunk by more than 10 meters over the past century due to excessive groundwater withdrawal.
• Consequences: Historical structures like the Metropolitan Cathedral are tilting, and the city’s drainage system has become inefficient, increasing flood risks.
• Solution: The government has implemented policies promoting rainwater harvesting, wastewater recycling, and groundwater recharge projects.

1. Jakarta, Indonesia

• Issue: One of the fastest sinking cities globally, experiencing subsidence rates of up to 25 cm per year.
• Consequences: Coastal flooding, damaged infrastructure, and threats to millions of residents.
• Solution: Jakarta is relocating its capital, implementing groundwater extraction limits, and investing in seawalls.

1. California, USA

• Issue: The San Joaquin Valley has subsided by over 9 meters in some areas due to over-pumping groundwater for agriculture.
• Consequences: Roads and canals have been damaged, and water supply networks have been disrupted.
• Solution: Strict water management laws, investment in groundwater recharge, and technological advancements in water conservation.

Iran’s Land Subsidence Crisis

1. Current Situation

Iran faces one of the world’s most severe land subsidence crises, particularly in Tehran, Isfahan, and Mashhad.

• Tehran: Sinking at a rate of 25 cm per year, threatening urban infrastructure and water supply networks.
• Mashhad: High groundwater extraction for agriculture has led to visible cracks in roads and buildings.
• Isfahan: The drying of the Zayandeh Rud River has worsened subsidence, endangering historical monuments like Si-o-se-pol Bridge.
• Yazd and Kerman: These desert cities are experiencing accelerated subsidence due to climate change and overuse of underground water.

1. Causes in Iran

• 85% of Iran’s water supply comes from underground sources, leading to excessive depletion.
• Severe droughts have reduced surface water availability, increasing dependence on underground reserves.
• Agricultural inefficiencies, such as flood irrigation, contribute to groundwater depletion.
• Urbanization and heavy construction exert additional pressure on unstable land.

1. Consequences in Iran

• Damage to Critical Infrastructure: Roads, railways, and buildings have developed deep cracks.
• Increased Earthquake Risk: Unstable land exacerbates seismic vulnerabilities.
• Water Crisis: Over-extraction accelerates depletion, leading to shortages.
• Desertification: Productive lands are turning into deserts at an alarming rate.

Solutions to Land Subsidence in Iran

1. Sustainable Water Management

• Enforcing Groundwater Extraction Limits: Implement strict regulations and monitor well usage.
• Rainwater Harvesting: Encourage collection and use of rainwater for irrigation and industrial use.
• Treated Wastewater for Agriculture: Promote wastewater recycling to reduce dependence on underground sources.

1. Agricultural Modernization

• Efficient Irrigation Techniques: Transition from flood irrigation to drip irrigation to conserve water.
• Drought-Resistant Crops: Encourage farming of crops that require less water.

1. Infrastructure & Urban Planning

• Reinforcing Buildings and Roads: Use advanced materials to withstand subsidence effects.
• Restricting Development in High-Risk Zones: Avoid construction in areas prone to severe subsidence.

1. Groundwater Recharge Projects

• Artificial Recharge of Aquifers: Injecting water into depleted reservoirs to restore stability.
• Surface Water Storage and Dam Management: Ensure that dam operations support groundwater replenishment.

1. Policy & Public Awareness

• Strict Legal Frameworks: Heavy fines for illegal water extraction.
• Public Education Campaigns: Raising awareness about responsible water use and conservation practices.

Conclusion

Iran faces one of the world’s most alarming land subsidence challenges, threatening its cities, historical sites, and agricultural lands. However, by learning from global experiences and implementing sustainable water management strategies, Iran can mitigate the crisis.

Urgent actions are needed to prevent irreversible damage and ensure water security for future generations. Sustainable policies, modernized agriculture, and technological advancements in water conservation will be key to protecting Iran’s future from this growing environmental disaster.

منابع اصلی:

1. United Nations (UN) Reports on Land Subsidence
   • UN Environment Programme (UNEP) reports on water scarcity and land degradation.
   • UN-Water publications on groundwater depletion and sustainable water management.
2. United States Geological Survey (USGS)
   • Reports on land subsidence in California’s San Joaquin Valley.
   • Groundwater depletion studies and the effects on infrastructure.
3. World Bank & Global Research Institutions
   • Case studies on Jakarta, Indonesia and Mexico City regarding rapid urban subsidence.
   • Sustainable water management policies in regions affected by over-extraction.
4. Iranian Government and Academic Research
   • Reports from the Iran Water Resources Management Company.
   • Academic papers from Iranian universities in Tehran, Isfahan, and Mashhad’s subsidence crisis.
   • Studies published in the Journal of Water and Soil Science (Iran) regarding desertification and groundwater overuse.
5. NASA & Satellite Data
   • Use of satellite imagery to track subsidence rates in Iran, Mexico, and Indonesia.
   • Data from GRACE satellites monitoring groundwater depletion globally.
6. International Hydrology and Geology Journals
   • Studies published in journals such as Hydrogeology Journal and Environmental Earth Sciences discussing the technical causes and mitigation strategies for land subsidence.

https://www.researchgate.net/publication/361375209_Shrinking_aquifers_and_land_subsidence_in_Iran?utm_source=chatgpt.com

https://www.researchgate.net/publication/352821972_LAND_SUBSIDENCE_HAZARD_IN_IRAN_REVEALED_BY_COUNTRY-SCALE_ANALYSIS_OF_SENTINEL-1_INSAR?utm_source=chatgpt.com

https://www.researchgate.net/publication/345650223_Land_Subsidence_Susceptibility_Mapping_in_Jakarta_Using_Functional_and_Meta-Ensemble_Machine_Learning_Algorithm_Based_on_Time-Series_InSAR_Data?utm_source=chatgpt.com

https://www.researchgate.net/publication/238391121_Evolution_of_long-term_land_subsidence_near_Mexico_City_Review_field_investigations_and_predictive_simulations?utm_source=chatgpt.com