Isotopic and hydrochemical datasets for preferential flow in Kumamoto vadose zone

This dataset contains hydrochemical and stable isotopic data (d-excess, δ15N, and δ18O of nitrate) obtained from soil pore water analysis in the volcanic vadose zone of the Kumamoto region, Japan. It includes depth profiles of major ions, water stable isotopes, nitrate isotope ratios, and soil physical/hydraulic properties collected from soil core drilling at the Ueki and Koshi sites. These data support the research paper investigating rainfall-induced preferential flow and nitrate transport in deep vadose zones.