Increasing Drought Risks Over the Past Four Centuries Amidst Projected Flood Intensification in the Kabul River Basin (Afghanistan and Pakistan)—Evidence From Tree Rings

The Kabul River is a transboundary river spanning eastern Afghanistan and northern Pakistan. It is an important tributary of the Indus, one of the world’s largest rivers with intensive water withdrawals for human use. With climate change, the Kabul River is projected to have more frequent and larger floods, but the projections are very uncertain. To have a better understanding of these future projections, we need to look at how the region’s climate has changed in the past. Tree rings are a valuable source of information to serve that need. Using old-growth conifers from the Hindu Kush Mountains, western Himalaya, we reconstruct four centuries of precipitation (rainfall) history for the Kabul River Basin. From the reconstruction, we observe that dry years are getting drier. Thus, the risks of severe droughts are increasing. Prolonged droughts are being replaced by shorter but more frequent ones, and periods of sustained high precipitation are also becoming more frequent. When seen in combination with earlier reports, our results imply that the Kabul River Basin is facing both floods and drought risks, and these are significant threats to the water security of the basin.