35. Numerical Modelling of Tidal Hydrodynamics Along River Tapi, Gujarat

Tapi, the second-largest westward draining river in India, originates at Multai reserve forest in Betul District, Madhya Pradesh, at 752 m. It runs westward for 724 km until discharging into the Arabian Sea via the Gulf of Khambhat. The basin is located between latitudes 20° 5' and 22° 3' north, and longitudes 72° 38' and 78° 17' east. The study aims to better understand the hydrodynamics of the tidally impacted river Tapi and estimate river discharge owing to rainfall at the ONGC bridge in Surat, which is about 14 km from the Arabian Sea. In order to achieve the goals, a two-dimensional hydrodynamic model was created using the Delft3D modelling scheme. The numerical model’s offshore ocean boundary is forced with tidal constituents, while the upstream river boundary is forced with discharge estimated using HEC-HMS (hydrological modelling software). The model estimated tide-induced currents are validated using observed field datasets, and it shows a good correlation. The model results indicated the tidally varying hydrodynamic behaviour during the year’s pre and post-monsoon seasons.