A new methodology for determining dispersion coefficient using ordinary and partial differential transport equations.

Area of Science:

• Environmental Science
• Hydrology
• Water Quality Management

Background:

• Natural streams are often degraded by artificial interferences like weirs and culverts, complicating dispersion coefficient calculations.
• Previous methods for determining dispersion coefficients face limitations in complex and altered natural stream environments.

Purpose of the Study:

• To develop and validate a robust methodology for determining the effective dispersion coefficient in environmentally degraded streams.
• To address the challenges posed by artificial interferences in natural water bodies for accurate dispersion analysis.

Main Methods:

• A sequential combination of the N-Tank-In-Series (NTIS) model and the Advection-Dispersion-Reaction (ADR) model was employed.
• Field measurements and intensive water quality data monitoring for E. coli were conducted on Gwangju (GJ) Creek during a rainy day.
• The methodology was validated using E. coli dispersion data from the monitored stream.

Main Results:

• The proposed methodology successfully estimated the effective dispersion coefficient for GJ Creek at 1.25 m(2)/s.
• The sequential combined method generated Number of tank-Velocity-Dispersion coefficient (NVD) curves.
• These NVD curves facilitate the convenient evaluation of dispersion coefficients in other river and stream systems.

Conclusions:

• The developed methodology offers a general and simple approach for determining effective dispersion coefficients in complex stream channels.
• The findings are applicable to various rivers and streams, providing a valuable tool for water quality management and environmental assessment.
• This study enhances the understanding of pollutant transport in anthropogenically altered aquatic ecosystems.