Field variation of groundwater recharge and its uncertainty via multiple tracers' method in deep loess vadose zone

Han Li; Min Li; Changhong Miao; Bingcheng Si; Yanwei Lu

doi:10.1016/j.scitotenv.2023.162752

Field variation of groundwater recharge and its uncertainty via multiple tracers' method in deep loess vadose zone

Sci Total Environ. 2023 Jun 10:876:162752. doi: 10.1016/j.scitotenv.2023.162752. Epub 2023 Mar 10.

Authors

Han Li¹, Min Li², Changhong Miao³, Bingcheng Si⁴, Yanwei Lu⁵

Affiliations

¹ Key Research Institute of Yellow River Civilization and Sustainable Development & Collaborative Innovation Center on Yellow River Civilization jointly built by Henan Province and Ministry of Education, Henan University, Kaifeng 475001, China; Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China. Electronic address: lihan2020@henu.edu.cn.
² Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China.
³ Key Research Institute of Yellow River Civilization and Sustainable Development & Collaborative Innovation Center on Yellow River Civilization jointly built by Henan Province and Ministry of Education, Henan University, Kaifeng 475001, China. Electronic address: chhmiao@henu.edu.cn.
⁴ College of Resources and Environmental Engineering, Ludong University, Yantai, Shandong 264025, China; Department of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada. Electronic address: bing.si@usask.ca.
⁵ Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of Ministry of Education, School of Water and Environment, Chang'an University, Xi'an 710054, China.

PMID: 36906021
DOI: 10.1016/j.scitotenv.2023.162752

Abstract

Accurate estimation of groundwater recharge is a precondition for assessing its spatial variation at different scales, especially field scale. In the field, the limitations and uncertainties of different methods are first evaluated based on site-specific conditions. In this study, we evaluated field variation in groundwater recharge via multiple tracers in the deep vadose zone on the Chinese Loess Plateau. Five deep soil profiles (approximately 20 m deep) were collected in the field. Soil water content and particle compositions were measured to analyse soil variation, and soil water isotope (³H, ¹⁸O, and ²H) and anion (NO₃^- and Cl^-) profiles were used to estimate recharge rates. Distinct peaks in soil water isotope and nitrate profiles indicated a vertical one-dimensional water flow in the vadose zone. Although the soil water content and particle composition were moderately variable, no significant differences were observed in recharge rates among the five sites (p > 0.05) owing to the identical climate and land use. The recharge rates did not show a significant difference (p > 0.05) between different tracers' methods. However, recharge estimates by the chloride mass balance method indicated higher variations (23.5 %) than those by the peak depth method (11.2 % to 18.7 %) among five sites. Moreover, if considering the contribution of immobile water in vadose zone, groundwater recharge would be overestimated (25.4 % to 37.8 %) using the peak depth method. This study provides a favourable reference for accurate groundwater recharge and its variation evaluated using different tracers' methods in deep vadose zone.

Keywords: Deep loess vadose; Field scale; Groundwater recharge; Multiple tracers; Peak depth method.