Which of the following processes is responsible for the formation of a Delta when river eater meets the sea water?

Coagulation

The correct answer is option 3. Coagulation.

A delta is a landform created by sediment deposition at the mouth of a river where it meets a larger body of water, such as an ocean, sea, or lake. Over time, the deposited sediments build up and create a new land area that extends into the body of water.

Sediment Transport

River Water and Sediments: Rivers transport a variety of sediments (e.g., silt, sand, clay) that they pick up from upstream sources, including eroded soil and rock particles.

Sediment Load: The sediment carried by river water is often suspended due to the river’s flow velocity, which keeps the particles in motion.

Coagulation and Sediment Deposition

Coagulation is the process where fine particles in a liquid aggregate or clump together to form larger particles or masses. This typically happens when the conditions favor the formation of floccules or larger aggregates. In the context of delta formation, coagulation occurs when river water carrying suspended sediments meets the sea or ocean. The decrease in the velocity of the river water as it enters the sea reduces the water’s ability to carry sediments.

How Coagulation Contributes to Delta Formation:

Velocity Reduction: As the river water flows into the slower-moving or still sea water, its velocity decreases. This reduction in flow speed means the water can no longer hold as much sediment in suspension.

Sediment Settling: The decrease in velocity leads to the sediment particles settling out of the water. This is where coagulation plays a role: fine suspended particles begin to clump together (coagulate) and settle as larger aggregates.

Sediment Deposition: As these particles settle, they form layers of sediment at the river’s mouth. Over time, these deposited sediments build up and create the characteristic triangular or fan-shaped landform known as a delta.

Examples and Observations

Real-World Examples: Famous deltas include the Nile Delta in Egypt, the Mississippi Delta in the United States, and the Ganges-Brahmaputra Delta in Bangladesh and India.

Delta Formation Process:

Sediment Load: River carries sediment towards the mouth.

Flow Reduction: River water slows down as it enters the sea.

Coagulation and Settling: Sediment particles aggregate and settle out of the water.

Deposition: Accumulation of sediments forms the delta.

Conclusion: Coagulation is the primary process responsible for sediment aggregation and deposition, leading to delta formation. It effectively explains why the sediments carried by rivers are deposited at their mouths, building up landforms over time.

So, the correct process for delta formation, given the options, is 3. Coagulation.