Relationship between turbidity and total suspended solids concentration within a combined sewer system

Area of Science:

• Environmental Science
• Water Quality Monitoring
• Hydrology

Background:

• Total suspended solids (TSS) are a key indicator of water quality.
• Turbidity is often used as a surrogate for estimating TSS concentrations.
• The relationship between turbidity and TSS can be influenced by various environmental factors.

Purpose of the Study:

• To confirm the linear relationship between turbidity and TSS concentration.
• To assess the variability of this relationship under different conditions (dry vs. wet weather, different sites).
• To evaluate the impact of calibration dataset size on estimating wet weather TSS concentrations.

Main Methods:

• Analysis of field data to establish the turbidity-TSS relationship.
• Comparison of the relationship's slope across dry and wet weather conditions.
• Assessment of inter-site and inter-event variability.
• Evaluation of estimation accuracy based on calibration dataset size.

Main Results:

• A strong linear relationship between turbidity and TSS was confirmed.
• The slope of the turbidity-TSS relationship exhibited significant variability between dry and wet weather, and across different sites.
• Limited variability was observed between sites and during dry weather.
• Significant inter-event variability in the turbidity-TSS relationship was identified.
• Turbidity provides acceptable accuracy for TSS estimation with reasonable sampling efforts during rainfall events.

Conclusions:

• Turbidity is a reliable proxy for estimating TSS concentrations, particularly during rainfall events.
• Understanding and accounting for the variability in the turbidity-TSS relationship is crucial for accurate water quality assessments.
• Effective rainfall event sampling strategies can leverage turbidity measurements for efficient TSS monitoring.