Effects of spatial and temporal variability in surface water inputs on streamflow generation and cessation in the rain–snow transition zone

Abstract. Climate change affects precipitation phase, which can propagate into changes in streamflow timing and magnitude. This study examines how the spatial temporal distribution of rainfall snowmelt discharge rain–snow transition zones. These zones experience large year-to-year variations cover a significant area mountain catchments globally, might extend to higher elevations under future climate change. We used observations from 11 weather stations snow depths measured one aerial lidar survey force spatially distributed snowpack model (iSnobal/Automated Water Supply Model) semiarid, 1.8 km2 headwater catchment. focused on surface water input (SWI; summation soil) for 4 years with contrasting climatological conditions (wet, dry, rainy, snowy) compared simulated SWI discharge. A strong agreement between depth (r2 = 0.88) was observed, median Nash–Sutcliffe efficiency (NSE) 0.65 at all modeled (0.75 normalized depths). The pattern consistent years, north-facing slopes producing 1.09–1.25 times more than south-facing slopes, snowdrifts up 6 catchment average. Annual not significantly correlated fraction falling as snow; instead, it magnitude spring rain. Stream cessation depended total precipitation, well melt-out date snowdrifts. results highlight importance heterogeneity zone generation cessation, emphasize need modeling or monitoring both dynamics.