Scale effect and landscape thresholds affecting water quality and dissolved organic matter

Area of Science:

• Environmental Science
• Ecology
• Hydrology

Background:

• River water quality and dissolved organic matter (DOM) are critical indicators for ecosystem health and water resource management.
• Understanding the influence of landscape patterns on these parameters is essential for effective watershed management strategies.

Purpose of the Study:

• To identify key spatial scales and landscape pattern metrics influencing seasonal variations in water quality and DOM in the Dan River Basin.
• To establish threshold relationships between landscape metrics and water quality fluctuations.
• To determine the primary anthropogenic sources of DOM and their contribution to water quality changes.

Main Methods:

• Quantified spatial scales and landscape pattern metrics affecting water quality and DOM.
• Analyzed seasonal variations in water quality and DOM in the Dan River Basin.
• Investigated the influence of landscape metrics on DOM components using fluorescence spectral indices.
• Assessed the contribution of non-point source pollution to DOM.

Main Results:

• The 100m riparian buffer zone emerged as the critical spatial scale influencing water quality and DOM.
• Landscape pattern metrics explained the highest proportion of variance in water quality and DOM during the normal season (70.93%).
• Key landscape indicators identified were land use intensity (L), contagion index (CONTAG), shape index (SHAPE), Shannon's diversity index (SHDI), and forest cover.
• Non-point source inputs were the primary anthropogenic source of protein-like DOM, contributing 55.4%.

Conclusions:

• Maintaining specific thresholds for land use intensity, contagion, shape index, diversity index, and forest cover within the 100m riparian buffer zone is crucial for water quality protection.
• Effective aquatic environment protection requires integrating scale-specific landscape planning with targeted pollution source control.