Climate and landscape control of runoff stable isotopes in the inland mountain

Study region: The Xiying River Basin is a typical inland mountainous watershed located in the Qilian Mountains. Study focus: This article reveals the change of runoff stable isotopes and their control mechanisms based on isotope data of different water bodies (precipitation, runoff, groundwater, and glacial snowmelt) in the Xiying River Basin from 2016 to 2021, combined with relevant meteorological observation data and the Normalized Vegetation Index (NDVI). New hydrological insights for the region: The results show that (1) meteorological factors control runoff isotope variations through controlling the evaporation process of runoff and the isotopic characteristics of recharge sources. (2) In areas with low vegetation cover, surface landscape features influence runoff isotopic composition by altering the isotopic characteristics of recharge sources. (3) In areas with high vegetation cover, surface vegetation cover affects runoff stable isotopes by controlling evapotranspiration processes. This study connects vegetation cover and runoff isotopes to explain the surface landscape control of runoff stable isotopes. It offers a more powerful reference for elucidating the factors influencing runoff isotopes in inland mountain watersheds.