Isotopic, hydrochemical, and hydrological data for streamflow and groundwater in a catchment of North China

This dataset supports the manuscript titled “Extreme precipitation-driven hydrologic connectivity and hydrochemical dynamics in a monsoonal mountain catchment: carbonate weathering dominance and storm-activated nitrate contamination.” It includes isotopic, hydrochemical, and hydrological data for precipitation, streamflow, and groundwater—key variables analyzed in the study. Each entry in the Excel file corresponds directly to a specific figure in the manuscript, ensuring traceability between raw data and the visual results presented.