Modeling Contaminant Microbes in Rivers During Both Baseflow and Stormflow

Area of Science:

• Environmental Microbiology
• Hydrology
• Water Quality Modeling

Background:

• Rivers are critical pathways for contaminant microorganism transport from various sources, posing significant public health risks.
• Understanding the dynamics of microbial transport, immobilization, and remobilization is essential for effective water resource management.

Purpose of the Study:

• To develop and validate a mobile-immobile model simulating contaminant microbe and particle transport in rivers.
• To investigate the influence of baseflow and stormflow conditions, including hyporheic exchange, on microbial and particle dynamics.

Main Methods:

• A mobile-immobile mathematical model was developed to simulate contaminant transport, immobilization, and remobilization.
• The model incorporates hyporheic exchange processes during baseflow and stormflow.
• Model predictions were validated against field observations of E. coli and turbidity during artificial and natural flood events.

Main Results:

• The model accurately predicted the timing and magnitude of E. coli and turbidity during multiple high-flow events.
• Hyporheic exchange was identified as a key mechanism for particle accumulation and slow remobilization during baseflow.
• Stormflow significantly increased the remobilization of stored particles and associated contaminants.

Conclusions:

• The developed model provides a robust framework for predicting contaminant microbe and particle behavior in streams.
• Accounting for flow states and hyporheic exchange is crucial for accurate water quality modeling.
• This research offers valuable insights for managing microbial contamination in riverine ecosystems.