Correct Option
The correct order of the process of soil erosion by water is Splash erosion, Sheet erosion, Rill erosion, and Gully erosion. This sequence represents the progressive stages of soil detachment and transport by water.
- Splash erosion: This initial stage occurs when the impact of raindrops directly dislodges individual soil particles from the soil surface.
- Sheet erosion: Following splash erosion, surface runoff transports the dislodged soil particles uniformly in a thin layer over the land surface. This stage often goes unnoticed until significant topsoil loss has occurred.
- Rill erosion: As the volume and velocity of surface runoff increase, it concentrates into small, well-defined channels known as rills. These channels are typically shallow and can often be removed by normal tillage operations.
- Gully erosion: This is the most advanced and severe stage, where rills deepen and widen into larger, permanent channels called gullies. Gullies cannot be removed by ordinary tillage and represent a significant loss of productive land.
Incorrect Options
- Option 2 (Sheet erosion, Splash erosion, Gully erosion, Rill erosion): This order is incorrect because splash erosion is the initial stage, occurring before sheet erosion. Additionally, rill erosion typically precedes gully erosion, as gullies develop from enlarged rills.
- Option 3 (Rill erosion, Gully erosion, Sheet erosion, Splash erosion): This sequence is incorrect as it reverses the natural progression of erosion. Splash erosion is the initial stage, followed by sheet, rill, and then gully erosion, which represents increasing severity.
- Option 4 (Gully erosion, Rill erosion, Sheet erosion, Splash erosion): This option presents a reverse order of the erosion process. Gully erosion is the final and most severe stage, not the beginning. The process starts with splash erosion.