Characterizing the water residence time of different runoff components for rainfall-runoff events in Hydrohill experimental catchment.

Distribution of residence time has been commonly used to characterize the responsecatchment runoff processes. Most previous studies on water residence time have been mainlyfocused on large scale analysis in time and space and on estimating residence timedistribution of total runoff. In this study, we analyzed residence time distribution (RTD) ofdifferent runoff components at event scale in Hydrohill experimental catchment, which islocated in Chuzhou City, Anhui Province, China. Hydrochemical and isotopic data, i.e., 18O,D, anions (HCO3−, Cl−, NO3−, SO42− and F−), cations (K+, Na+, Ca2+ and Mg2+) anddissolved Si in water samples were collected during the rainfall events in 2016, which areused to characterize the response of different runoff components by combining lumpedparameter models. Results showed that 18O and Cl− are the most suitable indicators toevaluate RTD of runoff components. On the experimental catchment scale, groundwaterrunoff gets the longest residence rime among all three runoff components. Residencerime of interflow runoff is approximately 1.38 times longer than that of surfacerunoff. Hydro-chemical tracing provide an effective way to easily measure andunderstanding hydrological processes for critical zone, which could support hydrologicalmodel development by strengthening physical base of hydrological cycle. However,what caused difference in residence time of runoff components and how to quantifyinteraction between different runoff components should be enhanced in furtherstudy. Key words: water residence time; runoff components; lumped parameter models;hydro-chemical and isotopic data; Hydrohill experimental catchment Acknowledgements: The work has been supported by National Natural ScienceFoundation of China (Grant No. 41830863) and National Key Research and DevelopmentPrograms of China (Grant No. 2016YFA0601501) [ABSTRACT FROM AUTHOR]