Evaporation loss estimation of the river-lake continuum of arid inland river: Evidence from stable isotopes

Abstract. Stable isotopes could be used as tracers to estimate the evaporation loss of surface water, which provides a new perspective for the research of hydrological processes. A systematic observation station has been built in the Shiyang River Basin, one of the most important inland river basins in Northwest China. This work conducted systematic observations on the river water, precipitation and hydrometeorology of the Shiyang River from 2017 to 2019. The evaporation loss of the Shiyang River is estimated to be 1.30 % in the mountainous rivers, 2.28 % in the mountainous reservoir (Xiying Reservoir), 2.87 % in the oasis rivers, 7.97 % in the oasis reservoir (Hongyashan Reservoir), and 41.37 % in the terminal lake (Qingtu Lake). No matter in mountain or oasis, the evaporation loss of reservoir is much higher than that of the river, and the evaporation loss of the terminal lake is the largest. The evaporation loss of the river-lake continuum accounts for 14.66 % of the total water volume of rivers and lakes (reservoirs). This work enriches the study of stable isotopes in the field of evaporation loss in the river-lake continuum, expands our understanding of the hydrological cycle in arid regions.