Zhao et al. (2026) Impacts of storm events on watershed phosphorus critical source area identification based on SWAT model

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-01-27
• Authors: He Zhao, Xiaorong Liu, Xinzhong Du, Qiuliang Lei, Hongbin Liu
• DOI: 10.1016/j.jhydrol.2026.135032

Research Groups

• Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs/ Changping Soil Quality National Observation and Research Station /State Key Laboratory of Efficient Utilization of Arable Land in China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
• School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China

Short Summary

This study investigated the impact of storm events on phosphorus (P) critical source area (CSA) identification in an agricultural headwater watershed using the SWAT model. It revealed that P loss is predominantly event-driven, with storm-event-based analysis identifying more CSAs and higher P loads compared to annual average assessments.

Objective

• To investigate the impacts of storm events on phosphorus (P) critical source areas (CSAs) identification in an agricultural headwater watershed.

Study Configuration

• Spatial Scale: An agricultural headwater watershed in southwest China.
• Temporal Scale: Event-driven analysis focusing on different storm events, compared to annual average scale. The model operates on a daily time step.

Methodology and Data

• Models used: SWAT (Soil Water Assessment Tool) model, integrated with the cumulative pollution load curve method.
• Data sources: Not explicitly detailed in the provided text.

Main Results

• Total phosphorus (TP) loss dynamics in the watershed are predominantly event-driven.
• Storm-event-based analysis identified more subbasins as CSAs and potential risk areas compared to CSAs identification on the annual average scale.
• As storm event levels increased, the number of CSAs, their TP load intensity, and their contribution to total pollution significantly rose.
• Key factors influencing P loss and the spatial distribution of CSAs include slope, soil type, and land use, with cultivated lands (due to anthropogenic fertilizer inputs) being primary contributors.

Contributions

• Confirms the dominant role of storm events in phosphorus export from watersheds.
• Underscores the importance of considering storm events for accurate identification of phosphorus critical source areas at the watershed scale, addressing a gap in understanding variations under different storm events.

## Funding -

Citation

@article{Zhao2026Impacts,
  author = {Zhao, He and Liu, Xiaorong and Du, Xinzhong and Lei, Qiuliang and Liu, Hongbin},
  title = {Impacts of storm events on watershed phosphorus critical source area identification based on SWAT model},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.135032},
  url = {https://doi.org/10.1016/j.jhydrol.2026.135032}
}