Understanding River Classifications: Ganga in UP and Bihar

Rivers change their form and characteristics as they flow from their source in the mountains towards the plains and finally to the sea. These changes result in different classifications based on their shape and behavior. The question asks about the classification of the river Ganga specifically in the reach that flows through Uttar Pradesh (UP) and Bihar.

Characteristics of River Types

Let's look at the typical characteristics of the river types mentioned in the options:

• Straight River: Rivers are rarely perfectly straight for significant distances. Straight sections often occur in steep mountainous areas or are artificially engineered.
• Meandering River: These rivers develop sinuous curves or loops across flat or gently sloping plains. They erode on the outer bend (cut bank) and deposit sediment on the inner bend (point bar), causing the bends to migrate over time. This pattern is common in alluvial plains.
• Braided River: These rivers have multiple, shifting channels separated by temporary islands or bars made of sediment. They typically occur in areas with a large supply of sediment, easily erodible banks, and variable discharge.
• Deltaic River: This refers to the distributaries formed by a river as it enters a larger body of water (like a sea or lake), depositing sediment and forming a delta. This classification applies near the mouth of the river.

Analyzing the Ganga River in UP and Bihar

The Ganga river, after descending from the Himalayas, enters the vast Indo-Gangetic plain. The stretch through Uttar Pradesh and Bihar is characterized by:

• Very flat terrain with a gentle gradient.
• Flow over alluvial (sediment) deposits.
• Significant deposition of sediment carried from the upstream mountainous regions.
• Lateral erosion and deposition processes.

These conditions are ideal for the development of meanders. As the Ganga flows through these plains, its channel curves and bends prominently. The gentle slope and the easily erodible alluvial soil allow the river to erode the outer banks of curves and deposit sediment on the inner banks, leading to the formation and migration of sweeping loops or meanders.

Eliminating Other Options

• The Ganga in UP and Bihar is not primarily a straight river for long stretches due to the flat, alluvial plain environment which favors lateral movement.
• While some sections might exhibit characteristics leaning towards braiding, the predominant pattern across large parts of UP and Bihar is the development of well-defined meanders. Braided rivers are more common in areas with higher sediment load and steeper gradients where the river energy fluctuates significantly, like in some Himalayan foothills.
• The deltaic river classification applies to the Ganga and Brahmaputra system only as it approaches the Bay of Bengal, forming the Ganges Delta, which is far downstream from UP and Bihar.

Therefore, based on the geomorphological characteristics of the terrain and the river's behavior in the Indo-Gangetic plains covering Uttar Pradesh and Bihar, the river Ganga is predominantly classified as a meandering river in this reach.

Revision Table: Ganga River in UP and Bihar

Additional Information: River Processes and Forms

The classification of a river reach depends on the balance between the river's energy (discharge and slope) and the resistance of the bed and banks (sediment size, bank stability). Different river types are associated with specific geomorphic processes:

• Erosion: The wearing away of river bed and banks. In meanders, erosion is strongest on the outer bend.
• Deposition: The dropping of sediment. In meanders, deposition occurs on the inner bend, forming point bars.
• Channel Migration: The movement of the river channel laterally and downstream over time, particularly evident in meandering rivers.
• Oxbow Lakes: Formed when a meander loop is cut off from the main river channel during floods, leaving behind a crescent-shaped lake. These are common features in floodplains of meandering rivers like the Ganga.

The river Ganga's morphology changes along its course. It might exhibit braided characteristics in steeper, sediment-rich upper reaches, becomes predominantly meandering in the vast plains of UP and Bihar, and forms a complex deltaic system near its mouth.