Identifying hydrological conditions of the Pihe River catchment in the Chengdu Plain based on spatio-temporal distribution of 2H and 18O

Stable isotope composition in precipitation, river water, and groundwater was used to investigate the hydrological conditions in the Pihe River catchment of Southwest China. Significant seasonal isotopic variations exist in precipitation and river water, and there is 1-month delay in the river water response to precipitation. The river water is gradually enriched under the influence of evaporation. However, due to the influence of recharge from external water source, the evaporation ratios do not strictly increase with the flow distance. The seasonal isotopic values in groundwater fluctuate the least. River water supplies groundwater more than precipitation in dry season.