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Watershed Planning within a Quantitative Scenario Analysis Framework
Published on: July 24, 2016
Coupling Hydrological Connectivity with Environmental Thresholds for Targeted Legacy Phosphorus Management in
Yunfei Cao1, Chuang Zhang1, Rui Hao2
1College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Environmental Science & Technology
|June 15, 2026
Summary
Legacy phosphorus (P) in soils can cause delayed water pollution. Our study reveals P transport lags over 10 years, highlighting the need for dynamic management strategies considering soil P dynamics and environmental factors.
Area of Science:
- Environmental Science
- Soil Science
- Water Quality Management
Background:
- Legacy phosphorus (P) in soils, from past human activities, poses a persistent threat to water quality.
- Remobilization of legacy P under changing hydrological conditions causes delayed pollution impacts, complicating management efforts.
- Current strategies often overlook legacy P dynamics and spatiotemporal lags, limiting pollution control effectiveness.
Purpose of the Study:
- To develop a novel management framework integrating hydrological connectivity and machine learning for legacy P.
- To elucidate the governance of legacy P transport by hydrological connectivity and identify environmental thresholds.
- To propose a dynamic, threshold-based framework for mitigating long-term legacy P impacts.
Main Methods:
- Developed a management framework integrating hydrological connectivity and interpretable machine learning.
- Utilized an aggregated index of connectivity to analyze legacy P transport.
- Identified environmental thresholds and key drivers (precipitation, ground surface temperature) modulating P transport.
Main Results:
- A phosphorus transport lag exceeding 10 years was observed in the Xiangjiang River Basin.
- Legacy P accounted for over 80% of the total phosphorus flux.
- Agricultural areas with high connectivity were primary legacy P sources; forests acted as temporary sinks with sudden-release risks.
- Precipitation and ground surface temperature exhibited critical thresholds influencing connectivity's role in P transport.
Conclusions:
- Legacy P dynamics and spatiotemporal lags are critical for effective water quality management.
- A dynamic, threshold-based management framework considering hydrological connectivity and environmental drivers is proposed.
- Targeted mitigation strategies are needed for long-term legacy P impacts in subtropical watersheds.
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