Our solution: a multi-pronged effort
Currently, the waterway only caters to 1.0 million metric tonnes per annum (MMTPA) of cargo. However, within the next decade, about 35 MMTPA of cargo is expected on it. Thus, it needs to be more navigable and capable of handling this steep increase in cargo transport volumes in the coming years.
We conducted a study to evaluate the techno-economic feasibility of achieving 3.0 m LAD for smoother and more consistent navigation in the 330 km Allahabad-Ghazipur stretch. This is because, although Allahabad and Varanasi are the main potential cargo areas, the river flows through Ghazipur from Haldia, with depth maintained at 2-2.5 m only.
For this study, IWAI provided us with water level information, depth data and bathymetry details of the entire stretch. Using our one-dimensional MIKE 11 (now MIKE HYDRO River) model, we simulated water levels for various flow conditions. We then compared the predicted data with measured levels to calibrate the model for the flow conditions. Following this, sediment transport, erosion and deposition was also modelled for the existing situation.
The aim of the mathematical modelling was to resolve the flow all along the stretch in the existing conditions and also with the proposed measures to maintain the 3.0 m LAD. A number of solutions needed to be evaluated for improving the waterway’s navigation and cargo handling capabilities. These river training measures included:
- bed vanes to induce secondary currents
- dredging – excavation activity to remove sediment deposits and dispose them elsewhere
- bandalling – a bamboo structure used for river course stabilisation by protecting against bank erosion
- submerged groynes to maintain the main channel
- bank revetment – sloping structures placed on the banks in such a way as to reduce bank erosion
- barrages – artificial obstructions built in the river to increase its depth
To evaluate all these possible solutions, we tested the hydraulic and morphological characteristics of the various solutions.