Balancing river water pollution and agricultural development: A tradeoff threshold approach

Area of Science:

• Environmental Science
• Agricultural Science
• Water Resource Management

Background:

• Balancing agricultural development and environmental protection is a key challenge in land use management.
• Agricultural expansion, particularly tea plantations, can impact water quality through non-point source pollution.

Purpose of the Study:

• To analyze the tradeoff between tea plantation expansion and river water quality.
• To identify critical thresholds for tea plantation expansion to prevent water quality deterioration.

Main Methods:

• Utilized the Soil and Water Assessment Tool (SWAT) model to simulate land use changes and their impact on river water pollution.
• Analyzed the relationship between the proportion of tea plantation area (Tea%) and nutrient concentrations (NO3--N, TN) over 20 years.

Main Results:

• Tea plantation area increased from 44 km² to 169 km² between 2000 and 2020, primarily at the expense of forest land.
• Mean NO3--N and TN concentrations increased by 100% and 91%, respectively, with NO3--N comprising over 80% of TN in tea plantation areas.
• Critical thresholds for Tea% to avoid abrupt water quality decline increased from 3.0% in 2000 to 18% in 2020, indicating reduced sensitivity due to accelerated nutrient pollution.

Conclusions:

• River water quality is significantly impacted by the expansion of tea plantations, particularly concerning nitrogen pollution.
• Establishing and monitoring Tea% thresholds is crucial for sustainable agricultural land use and water resource protection.
• The study provides empirical evidence for the carrying capacity of river ecosystems concerning agricultural expansion.