Numerical modelling of pollutant dispersion affecting water quality of Upper Ganga Canal (Roorkee City, India)

Abstract

In water quality literature, in-situ data collections and their experimental investigations are prevalent; however, numerical modelling of flow of water in waterbodies are rare in literature. The pollutant dispersion affecting water quality must be explored. In the study, a three-dimensional numerical model was developed to analyze water flow and pollutant dispersion in the Upper Ganga Canal (UGC) from the old canal bridge to the Ganeshpur bridge in Roorkee. The model simulated pollutant inflow from five sewage outlets and examined the impact of varying sewage velocities (0.2 m/s, 0.4 m/s, and 0.6 m/s) on pollutant concentrations. Results showed that pollutant concentration is maximum near the canal banks and minimum at the centre of the canal. The study also tracked the movement of solid particles, revealing that particles larger than 80 µm settled quickly, with 100% of particles settling at the base, whereas smaller particles (< 25 µm) remained suspended longer, with only 30% settling. The findings indicate that sewage pollutants predominantly affect water concentration near the canal banks and are proportional to the number of sewage inlets and their velocities. This model provides critical insights into the dispersion of pollutants in canal systems, essential for improving water quality management strategies.