Hydrogen and oxygen isotopic characteristics analysis of different water body under changing environment-A Case study on typical small watershed of Loess Plateau in China

This paper studies typical small watershed in the Loess Plateau of China, thus analyzed the characteristics of stable hydrogen and oxygen isotopes in precipitation, surface water, soil water and groundwater under the annual timescale in Zhifanggou Watershed of Ansai District. The study integrates fieldwork and laboratory test, and aims to provide scientific basis for local ecological conservation and reconstruction in the Loess Plateau. The δ2H range of variation in precipitation, surface water and groundwater in the study area ranged from -24.9‰ to -76.5‰, -51.89‰ to -67.28‰ and -62.53‰ to -59.31‰ The δ18O range of variation in precipitation, surface water and groundwater in the study area ranged from -3.2‰ to -11.0‰, -6.21‰ to -8.86‰ and -8.71‰ to -8.23‰. The deuterium excess range of variation in precipitation, surface water and groundwater in the study area ranged from 1.0‰ to 11.8‰, -2.22‰ to 3.58‰ and 6.64‰ to 7.16‰. Precipitation isotope values affected by rainfall and temperature, and the hydrogen and oxygen isotopic values of precipitation, surface water, soil water and groundwater show different trends in annual timescale. Groundwater is originated from precipitation, and the precipitation takes more than a year to be converted into groundwater. © 2018, Taiwan Joint Irrigation Associations.