Question

Which is erosion where a rill becomes broader and deeper? A. gully C. runoff B. rill D. sheet

Short answer

Gully erosion is where a rill becomes broader and deeper.

Step-by-step solution

Understanding the Terminology

First, we need to understand the terms given in the options related to erosion. A 'rill' is a small channel formed by running water, while a 'gully' is a larger channel that forms when rills converge and erode further. 'Runoff' refers to the water flow over the surface of the land, and 'sheet' erosion involves the removal of a uniform layer of soil from the surface.

Analyzing the Process

A 'rill' becomes broader and deeper over time due to continued water erosion, which eventually transforms it into a 'gully'. This occurs as the erosive power of the moving water enlarges the rill, making it wider and deeper, which is characteristic of gully erosion.

Identifying the Correct Answer

Based on the definitions and analysis, the process by which a rill becomes broader and deeper describes the formation of a gully. Therefore, the correct answer is the option that corresponds to this process, which is 'gully'.

Key concepts

Gully Erosion

Gully erosion occurs when small channels, known as rills, are enlarged by the force of water moving across the land. This results in the formation of larger, more defined channels called gullies.

Gully erosion is a significant concern for land management because once gullies have formed, they continue to grow, exacerbating soil loss. The main features of gully erosion include:

• Deep and widescale cuts into the earth.
• Significant loss of topsoil, which affects land productivity.
• Increased sediment transport that can alter downstream water bodies.

Managing gully erosion requires stabilization techniques such as planting vegetation, constructing barriers or terracing to reduce the flow of water, and other soil conservation measures.

Rill Formation

Rill formation is the initial stage of erosion where small channels are carved into the soil by flowing water. These channels, or rills, typically occur during heavy rainfall when the ground is unable to absorb all the water.

• Rills are small, usually only a few centimeters deep.
• They often appear on slopes where water naturally flows downhill.
• Rill erosion is easier to correct than gully erosion, as they are less deep and wide.

Farmers can fill in rills and use planting methods that disrupt water flow, like contour plowing, to prevent their further development. If ignored, however, rills can deepen and widen to become gullies.

Water Erosion

Water erosion is the process by which soil is removed from the land by water. This can happen in various forms, such as rill, gully, or sheet erosion. Water erosion is highly dependent on several factors, including:

• The amount and intensity of rainfall.
• The type of soil and its current structure.
• The topography or shape of the land.

Preventing water erosion involves using best practices in land management, such as creating buffer zones of vegetation along waterways, using good agricultural techniques, and ensuring soil is covered and protected, particularly during heavy rain events.

Soil Erosion

Soil erosion is a natural process where soil is removed from the land, often exacerbated by human activities. Water and wind are the primary agents of soil erosion. The impacts of soil erosion can be severe, leading to:

• Loss of fertile land and reduced agricultural productivity.
• Siltation of waterways, which can lead to flooding.
• Degradation of landscapes, making recovery and reforestation challenging.

Steps to minimize soil erosion include planting ground-cover crops, using mulch, optimizing land use, and implementing engineering solutions like terraces or retaining walls. Awareness and education are crucial to ensure long-term prevention measures are consistently applied.