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Published on: December 9, 2012
Contribution of non-point source pollution that migrated with underground runoff process based on the SWAT model and
Ruimin Liu1, Yue Wang2, Yuexi Miao2
1State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Beijing, 100875, China. liurm@bnu.edu.cn.
Non-point source pollution primarily moves via surface runoff. Underground runoff contributes less, with its proportion varying by nutrient type, season, and location within the watershed.
Area of Science:
- Environmental Science
- Hydrology
- Water Quality Management
Background:
- Non-point source (NPS) pollution is a global research focus, necessitating understanding of pollutant migration for effective control.
- The Xiangxi River watershed's NPS pollution dynamics require detailed investigation to inform management strategies.
Purpose of the Study:
- To quantify the contribution of underground runoff (UR) to NPS pollution migration in the Xiangxi River watershed.
- To analyze the factors influencing the proportion of NPS pollution transported via UR, including precipitation, seasonality, and spatial distribution.
Main Methods:
- Utilized the Soil and Water Assessment Tool (SWAT) model combined with a digital filtering algorithm.
- Analyzed hydrological data from three selected years to differentiate pollution migration pathways.
Main Results:
- Surface runoff (SR) is the dominant NPS pollution pathway; UR accounted for only 30.9% of total NPS pollution.
- UR's proportion of total nitrogen (TN) decreased with lower precipitation, while total phosphorus (TP) increased.
- Pollution migration via UR showed monthly variations, with TP load lagging behind total load by one month due to hysteresis.
Conclusions:
- UR is a significant, albeit secondary, pathway for NPS pollution, particularly for TP in downstream areas.
- Management strategies must consider cumulative soil and groundwater nutrient contributions and differentiate control measures based on migration routes.
- Spatial variations in topography and land use significantly impact the proportion of TN and TP transported via UR.
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