Over the past two decades, the Central Plateau of Iran has been at the epicenter of the country’s most severe climatic stresses. This situation, characterized by a tangible decrease in precipitation, a worrying rise in temperatures, and the intensification of consecutive droughts, has pushed the region’s vital water reserves to the
brink of collapse. As a result of this devastating synergy, the Zayandeh Rud—the life-giving artery and symbol of Isfahan’s civilization—has ceased flowing multiple times, challenging not only the environment but also the foundations of agriculture, livelihoods, and social stability in the region.
The Worrying Trend of Climate Change
According to data from specialized centers and international reports, the Central Plateau of Iran has witnessed climate change with a steep gradient. Over the last three decades, the region has experienced ~1.2°C (based on regional IP-CC-aligned studies 1990-2020) . Simultaneously, annual precipitation has decreased by 15% to 25%, which has had direct and heavy consequences on renewable water resources. Climatological analyses indicate that a decrease of just 50 millimeters in Iran’s average rainfall leads to a drop of several billion cubic meters in renewable water resources.Furthermore, macro-climatic indices such as the Atlantic Multidecadal Oscillation (AMO), by in fluencing atmospheric flow patterns, have pushed the Central Plateau into long-term phases of low precipitation. During positive phases of this index, the region’s average rainfall has been recorded at approximately 9.7% lower than the long-term average.Standard drought indices, such as SPI (Standardized Precipitation Index) and SPEI (Standardized Precipitation Evapotranspiration Index), indicate that reduced rainfall coupled with increased evaporation has led to longer and more severe droughts. Changes in atmospheric patterns and the path of Mediterranean precipitation currents have rendered the Central Plateau more vulnerable to drought.One of the most serious consequences of rising
temperatures is the drastic increase in evaporation rates; scientific estimates suggest that every 1°C increase in temperature results in an approximately 7% increase in evaporation. This poses a direct threat to surface water reserves such as lakes, wetlands (including the Gavkhouni Wetland), and rivers, ultimately transforming the Central Plateau into a drier and hotter region with serious challenges in water resource access and management.Contemporary climatic studies also confirm that the average temperature in the Central Plateau has 0.4–0.6°C/decade over two decades, while the overall precipitation trend has been downward during the same period. The changing pattern of spatial and temporal precipitation distribution and its unbalanced fluctuations (ranging between -12% to +19%) have deprived the region of the oppor-tunity to replenish water resources, leading to the formation of chronic and intensified droughts over the past 15 years.
Consequences for Water Resources and Agriculture
The water resource crisis has directly struck the economic backbone of the Central Plateau: agriculture. Increasing water limitations for crop irrigation and a significant reduction in crop yields have ultimately resulted in deep economic losses for local communities. Research indicates that agricultural yields in this region show a severe negative reaction to every 1% decrease in rainfall, and experience a noticeable decline in efficiency in the face of rising temperatures. This situation, in addition to creating livelihood dilemmas, brings about the risk of soil erosion and forced migration.The cessation of flow in the Zayandeh Rud is not merely a climatic phenomenon; it is the inevitable consequence of climate change synergizing with unsustainable management policies. The survival of Isfahan’s ecosystem depends on immediate structural reforms and halting excessive burdens on this basin.
Anatomy of the Crisis: Why the Flow Stops
The cessation of flow in the Zayandeh Rud is not merely a climatic phenomenon; it is the inevitable consequence of the synergy between climate change, unsustainable management policies, and the excessive exploitation of water resources. Along-side reduced rainfall, key managerial factors in this trend include:
• Inter-basin Water Transfers: Water transfer projects to adjacent basins such as Kashan and Yazd have drastically reduced the river’s share of its his torical water rights.
• Upstream and Downstream Withdrawals: Unregulated agricultural development and industrial withdrawals have minimized the river’s flow rate (discharge).
• Increased Urban Consumption: Population growth and inappropriate urban consumption patterns have placed double the pressure on water resources.
• Groundwater Depletion: The drilling of deep and unauthorized wells in the river plains has led to a drop in the water table, depriving the river of its renewable resources.
The Necessity for Comprehensive Management and Climate Adaptation
The crisis of the Zayandeh Rud ceasing to flow has not only severely affected agriculture and the regional ecosystem but has also posed serious lively hood and social risks to the residents of the Central Plateau and the city of Isfahan. This worrying trend highlights the need for an immediate and comprehensive review of water resource utilization policies.To combat these existential challenges, it is essential to place comprehensive and integrated water resource management on the agenda. This includes prioritizing environmental and drinking water rights, developing climate adaptation strategies such as changing cropping patterns to low-water-consuming crops, increasing water efficiency in the industrial and agricultural sectors, and enforcing strict limitations on with drawals and inter-basin transfers. The survival of the ecosystem and livelihoods of the Central Plateau and the historic city of Isfahan is held hostage to structural reforms in this field.