(Prepared by Dr. Ali Ameli) Climate variability doesn't affect all watersheds equally—and new research reveals that the difference lies beneath the surface. A study published in Water Resources Research by Mahbod Taherian (Master of Applied Science student in Geological Engineering) and Dr. Ali Ameli (Assistant Professor) at the Department of Earth, Ocean and Atmospheric Sciences shows that year-to-year variations in Fall rainfall fundamentally alter how subsequent snowmelt moves through a watershed—whether it flows quickly to streams, seeps down to recharge groundwater, or returns to the atmosphere through plants. 

But the magnitude of this climate-induced shift depends critically on what lies underground. Watersheds with patchy subsurface structure—alternating zones of easy and restricted water flow—route snowmelt very differently depending on how wet the previous Fall was. In contrast, watersheds with uniform underground structure partition snowmelt consistently year after year, regardless of climate conditions in the Fall season prior to snow season. The findings suggest that predicting how water supply and flood risk will respond to climate change requires looking beyond surface characteristics to the hidden architecture below—a factor largely overlooked in current climate change impact assessment studies.