Priya Krishnan
Independent Researcher
India
ABSTRACT
This manuscript presents the application of the QUAL2K model for simulating water quality in open channels, focusing on parameter calibration, model performance, and statistical analysis aligned with engineering practices as of 2015. A case study river reach is selected to demonstrate model setup, input data preparation, and scenario analysis. Key water quality variables—dissolved oxygen, biochemical oxygen demand, ammonia nitrogen, and temperature—are simulated under baseline and stress scenarios. Model calibration employs observed field data collected in 2014. Statistical performance metrics, including the coefficient of determination (R²), percent bias (PBIAS), and Nash–Sutcliffe efficiency (NSE), are computed to evaluate accuracy. Results show R² values ranging from 0.76 to 0.89, PBIAS within ±15 %, and NSE above 0.65, indicating satisfactory model reliability. Identified research gaps include limited consideration of sediment–water interactions, uncertainty analysis under low-flow conditions, and the need for integrating advanced nutrient cycling modules. The manuscript concludes with recommendations for future developments in open-channel water quality modeling, emphasizing enhancements achievable with technologies available prior to 2016.
KEYWORDS
QUAL2K, open-channel modeling, dissolved oxygen, calibration, statistical performance
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