Environmental consequences of Caspian Sea desalination and water transfer to the central plateau of Iran

Abstract

The Caspian Sea (CS), the largest lake in the world, has reportedly experienced a significant water level decline over the past decades. As an ancient endorheic lake with no surface outflow, it is particularly vulnerable to climate change. The proposed desalination and water transfer project from the CS to Iran’s arid central plateau seeks to address water demands but could carry significant environmental risks. The project envisions transferring over 220 Million Cubic Meters (MCM) of desalinated water annually from an elevation of -27.5 m to 2312 m above sea level via eight pumping stations and two pipelines spanning 465 km. This process is estimated to require 448 megawatts (MW) of electricity and may discharge 2.6 million tons of salt into the CS annually. Brine discharge may increase local lake water salinity by up to 400% above standard limits within a 300-meter radius, posing risks to aquatic species. The annual release of 3.2 million tons of carbon dioxide (CO₂) and the loss of forests (70–100 ha), rangeland (738 ha), agricultural lands (161 ha), and high-quality soils (15 MCM) highlight possible ecological costs of the project. Additionally, outdated water transmission systems and water-intensive crop cultivation in receiving province (Semnan) could exacerbate inefficiencies in resource use. We suggest prohibiting the cultivation of non-strategic crops in the destination area to mitigate water resource depletion as a sustainable alternative. Without such measures, the environmental, economic, and social consequences of this project might be severe, with potentially far-reaching regional and global impacts.