[Water Quality Assessment and Spatial-temporal Variation Analysis in Yellow River Basin]

Area of Science:

• Environmental Science
• Water Resource Management
• Ecology

Background:

• Ecological protection in the Yellow River basin necessitates understanding water pollution and quality dynamics.
• Water safety is paramount, requiring detailed analysis of spatio-temporal water quality variations.
• Long-term monitoring data is crucial for assessing trends and informing environmental strategies.

Purpose of the Study:

• To analyze the spatio-temporal variation of water quality in the Yellow River basin from 2004 to 2018.
• To identify dominant pollution indicators and their seasonal characteristics.
• To provide scientific evidence for effective water pollution control and management strategies.

Main Methods:

• Collected water quality data from eight typical monitoring stations (2004-2018).
• Employed multivariate data analysis: Mann-Kendall (M-K) trend test, hierarchical clustering analysis (HCA), principal component analysis (PCA).
• Utilized a modified comprehensive water quality index (WQI) for assessment.

Main Results:

• Water quality exhibits seasonal variations (wet, normal, dry seasons) aligning with hydrological periods.
• Overall water quality shows a gradual improvement trend, with 2010 as a critical year.
• Ammonia nitrogen (NH4+-N) and permanganate index are dominant pollution indicators; station S6 is consistently heavily polluted.

Conclusions:

• Water quality in the Yellow River basin is improving, but seasonal and spatial disparities persist.
• Ammonia nitrogen and permanganate index are key indicators, linked to domestic, industrial, and agricultural sources, respectively.
• The modified WQI offers superior assessment capabilities, supporting targeted water management interventions.