Air temperatures in Asia have been rising since the 20th century, mainly due to global warming. This has changed the region's water cycle, leading to irregular and decreased rainfall. The Hindu Kush Himalaya (HKH) mountain range spans a large area across eight Asian countries. Known as the “Third Pole” and the Asian water tower, the HKH holds the largest freshwater reserves, mainly stored in glaciers and permafrost. Rising temperatures and less snowfall are causing massive glaciers and permafrost to melt, resulting in reduced river flow. Afghanistan's river basins originate from the HKH mountain range and recharge groundwater aquifers along their courses. The Helmand River Basin (HRB), the largest of Afghanistan’s five river basins, covers about 50% of the country and drains into Iran. As a key source of freshwater, the HRB is vital for agriculture, supporting diverse crop production. Yet the basin faces serious impacts from climate change, including rising temperatures, declining rainfall, and declining surface water levels. Beyond climate impacts, human activities have also worsened the situation, with population growth and the influx of millions of returnees from neighboring countries causing increased settlement and hardship for many residents. The combined effects of climate change and human activities have drastically altered the environment and hydrology of the HRB, leading to the drying up of large water bodies such as the Hamuns and Sistan, and significantly reducing river discharge volumes.

The decreased flow downstream has sparked disputes and conflicts between Afghanistan and Iran over transboundary water use. Both sides accuse each other of violating the 1973 water-sharing treaty. Recent and more severe border skirmishes have heightened tensions and the risk of broader military conflict. Aggressive rhetoric on both sides exacerbates this risk. Iran has accused Afghanistan of obstructing the river, diverting water for irrigation, and building dams. Iran has also used economic influence to pressure Afghanistan, including restrictions on trade and energy supplies. Additionally, Iranian authorities have been accused of supporting sabotage efforts to disrupt dam construction in Afghanistan, potentially escalating into covert warfare. This mistrust and poor cooperation remain major obstacles to sustainable basin management.

I conducted a study on updated climate change impacts, water resources, human activities, natural disasters, and the basin's potential for future sustainability. This research focused on quantifying mean annual temperature, precipitation, and river discharge over more than four decades, offering critical insights for irrigation, agriculture, hydropower planning, and climate change adaptation. There is ongoing skepticism and criticism from downstream countries about the decreasing trend in Helmand River discharge. Some attribute the decline to obstructions and upstream diversion of surface water, ignoring climate change impacts. My study estimates a negative trend in river discharge since 1980, supported by evidence of climate change effects using an independent, bias-free global gridded database. The findings highlight significant climate change impacts on the decline of surface water in the HRB. The results provide vital statistical data for future water resource management, environmental planning, and climate change mitigation and adaptation strategies in the HRB. These insights are also applicable to other river basins in the country. Moreover, the study documents a sharp decline in river discharge attributable to climate change, supporting transboundary negotiations.