Process based modelling of phosphorus losses from arable land.

Area of Science:

• Environmental Science
• Agricultural Science
• Hydrology

Background:

• Accurate modeling of phosphorus (P) discharge is crucial for managing agricultural runoff and implementing effective pollution control strategies.
• Understanding temporal and spatial variations in P discharge is essential for localizing abatement efforts.

Purpose of the Study:

• To develop models for agricultural phosphorus losses with enhanced spatial and temporal resolution.
• To compare the accuracy of a detailed process-based model (SWAT) against a rainfall-runoff coefficient-based model (WATSHMAN).

Main Methods:

• Implemented the Soil and Water Assessment Tool (SWAT) model across five Swedish river basins.
• Adapted model parameters for Scandinavian soil, crop, and management conditions.
• Compared SWAT results with the WATSHMAN model for one river basin.

Main Results:

• Model performance for flow dynamics was satisfactory, with comparable results across scales.
• Modeled P load showed high accuracy on daily validation days (monthly monitoring).
• The process-based SWAT model slightly outperformed WATSHMAN, though monthly P load accuracy was limited by monitoring frequency.

Conclusions:

• Process-based models like SWAT provide a more accurate representation of phosphorus losses than simpler coefficient-based models.
• Improved spatial resolution of input data (Soil-P, agricultural practices) is necessary for precise, locally adapted P management strategies.
• Further research should focus on enhancing spatial data granularity for more effective P abatement planning.