Improved export coefficient model for identification of watershed environmental risk areas

Area of Science:

• Environmental Science
• Ecosystem Management
• Water Quality Assessment

Background:

• Land use/cover change significantly impacts freshwater ecosystem quality.
• Accurate simulation of lake water quality is crucial for effective management.
• Classical export coefficient models have limitations in accounting for pollutant migration factors.

Purpose of the Study:

• To improve the classical export coefficient model by incorporating precipitation, surface cover, and topography.
• To evaluate the contribution of land use/cover to total nitrogen load in the Dianchi Lake Basin.
• To apply pollution assessment results for identifying watershed environmental risk areas.

Main Methods:

• Modification of the classical export coefficient model.
• Inclusion of factors like precipitation, surface cover, and topography.
• Spatial analysis of total nitrogen load contribution and risk area identification.

Main Results:

• The improved model accurately simulates the relationship between land use/cover and total nitrogen load into Dianchi Lake.
• Spatial characteristics of terrestrial contributions to nitrogen load were identified.
• High-risk areas, primarily cultivated and construction land with low vegetation, were pinpointed around the lake and downstream.

Conclusions:

• The enhanced export coefficient model provides a better simulation of nitrogen loads and spatial risk assessment.
• Land use control measures must be strengthened in high-risk areas, particularly in lakeside zones.
• Targeted interventions in high-risk areas can significantly reduce nitrogen loading into the lake.