Assessing characteristics and long-term trends in runoff and baseflow index in eastern Japan

Baseflow is the portion of streamflow derived from delayed subsurface pathways. The baseflow index (BFI) a ratio to total streamflow, and an important hydrological variable when linking watershed characteristics baseflow. ‘smoothed minima’ procedure separation was applied data (29–67 years) twenty-six gauges watersheds in eastern Japan. Mann-Kendall statistical test Sen’s slope estimator were used identify trends estimate rate change annual seasonal runoff BFI per decade at 0.01 0.05 significance levels. To best our knowledge, this first study investigate long-term for large-scale region Results showed significant BFI, with concentration occurring winter five showing nine BFI. results suggest that response climate can already be seen, which implies policymakers need more information on impacts human activities manage water resources sustainably.