Integrated export instream coefficient model for accurate nonpoint source pollution estimation and management in the...

Area of Science:

• Environmental Science
• Hydrology
• Water Quality Management

Background:

• The Export Coefficient Model (ECM) is widely used for Non-point Source Pollution (NPSP) estimation but struggles with complex watersheds.
• Accurate quantification of pollutant loads in large, intricate watersheds requires more advanced methods than traditional ECM.

Purpose of the Study:

• To develop and validate an enhanced model, the EC-Integrated Catchment Model (EC-ICM), for more accurate NPSP load assessment.
• To integrate environmental factors and optimized export coefficients (EC) for improved watershed management adaptability.
• To identify high-risk areas and provide targeted management strategies for pollution control.

Main Methods:

• Empirical EC values were derived using genetic algorithms (GA) and Latin hypercube sampling.
• The EC-ICM incorporates factors like runoff, topography, soil erosion, and pollutant production.
• Pollution factors were classified using natural breaks, with Entropy Weight method for risk assessment.

Main Results:

• The EC-ICM reduced relative errors for total nitrogen (TN) and total phosphorus (TP) by 9.66% and 6.68%, respectively, compared to GA-optimized ECM.
• Land use (cropland, grassland) is the primary source of TN loads, while livestock farming dominates TP loads.
• The Longdong Loess Plateau was identified as a high-risk area for NPSP.

Conclusions:

• The EC-ICM provides a more accurate and adaptable approach to NPSP estimation in complex watersheds.
• Risk-based zoning management strategies are crucial for effective pollution control in identified high-risk areas.
• Future research should explore temporal resolution, climate change impacts, and hydrodynamic model integration.