Zhou et al. (2026) A dual-threshold framework for antecedent wetness controls on hydrological connectivity and nitrate source dynamics in a subtropical agricultural watershed

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-09-11
• Authors: Jia Zhou, Hao Wu, Yucang Wang, Xinyi Jiao, Yuhan Han, Hongrui Wu, qi ling, Yi Pan, Zheqi Pan, Sijie Li, Kexin Xu, Guangle Dong, Xiaochen Liu, Minpeng Hu, Dingjiang Chen
• DOI: 10.1016/j.jhydrol.2026.136396

Research Groups

• State Key Laboratory of Soil Pollution Control and Safety, Zhejiang University
• College of Environmental & Resource Sciences, Zhejiang University
• Ministry of Education Key Laboratory of Environment Remediation and Ecological Health, Zhejiang University
• Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University

Short Summary

This study introduces a dual-threshold framework to control antecedent wetness effects on hydrological connectivity and nitrate source dynamics in a subtropical agricultural watershed. The framework identifies two operational thresholds that partition the hydrologic record into Baseflow, Transition, and Storm regimes.

Objective

• Investigate the impact of antecedent precipitation index (API7) and baseflow index (BFI) on hydrological connectivity and nitrate transport in a subtropical agricultural watershed

Study Configuration

• Spatial Scale: Subtropical agricultural watershed in eastern China
• Temporal Scale: Daily to monthly time scales, with data collected from 1980 to 2023

Methodology and Data

• Models used: Dual isotopes of water (δ2H-H2O, δ18O-H2O) and nitrate (δ15N-NO3 –, δ18O-NO3 –)
• Data sources: Daily precipitation and discharge records, monthly hydrochemical monitoring

Main Results

• Two operational thresholds were identified: 34.3 mm for initial hydrological activation and 133 mm for saturated connectivity
• Water isotopes showed that the first threshold mainly reflected increased discharge through displacement of stored, evaporatively enriched pre-event water
• Nitrate source dynamics revealed marked regime-dependent source reorganization in spite of weak concentration response

Contributions

• Introduced a process-based alternative to conventional dry/wet seasonal classification
• Provided new insights into antecedent wetness effects on hydrological connectivity and nitrate transport

Funding

• This research was funded by the State Key Laboratory of Soil Pollution Control and Safety, Zhejiang University (Grant No. SKLSPCS2023001)
• Supported by the Ministry of Education Key Laboratory of Environment Remediation and Ecological Health, Zhejiang University (Grant No. MELER-EH2023002)

Citation

@article{Zhou2026dualthreshold,
  author = {Zhou, Jia and Wu, Hao and Wang, Yucang and Jiao, Xinyi and Han, Yuhan and Wu, Hongrui and ling, qi and Pan, Yi and Pan, Zheqi and Li, Sijie and Xu, Kexin and Dong, Guangle and Liu, Xiaochen and Hu, Minpeng and Chen, Dingjiang},
  title = {A dual-threshold framework for antecedent wetness controls on hydrological connectivity and nitrate source dynamics in a subtropical agricultural watershed},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.136396},
  url = {https://doi.org/10.1016/j.jhydrol.2026.136396}
}