Certified Storm Water Operator Practice Exam

The three categories of overland erosion are:

1. Hydraulic, chemical, biological

2. Sheet, rill, gully

3. Surface, sub-surface, underground

4. Rill, sheet, deep

The correct answer is: Sheet, rill, gully

The three categories of overland erosion are indeed classified as sheet, rill, and gully erosion. Understanding these categories is essential for stormwater management and soil conservation practices. Sheet erosion refers to the thin layer of soil that is removed uniformly from a large area by the action of rainfall and surface runoff. This type of erosion typically occurs over broad, flat areas where water flows as a thin sheet across the surface, making it harder to detect until significant soil loss has happened. Rill erosion occurs when water concentrates into small channels, leading to the removal of soil along these pathways. This often happens on sloped surfaces where rainfall creates little rivulets that are powerful enough to remove soil but do not yet form larger channels or gullies. It is more easily seen and can be managed through effective land practices. Gully erosion represents a more advanced stage of erosion where water has carved out larger, deeper channels in the landscape. This type of erosion significantly impacts the landscape, affecting drainage patterns and leading to further soil degradation. Gullies can form from repeated runoff in the same areas, ultimately leading to larger areas of land degradation. These three types of erosion demonstrate the different processes by which water can remove soil from the landscape, helping outline effective strategies for erosion