1 only.Rill and gully erosionIn rill erosion, finger-like rills appear on the cultivated land after it has undergone sheet erosion.These rills are usually smoothened out every YEAR while forming.Each year the rills slowly increase in number become wider and deeper.Gully erosion is the removal of soil along drainage lines by surface water runoff.When rills increase in size, they become gullies.Once started, gullies will continue to move by headward erosion or by slumping of the side walls.Gullies formed over a large AREA give rise to badland topography (Chambal Ravines).When a gully bed is eroded further due to headward erosion, the bed gradually deepens and flattens out, and a ravine is formed.The depth of a ravine may extend to 30 meters.Water ErosionRunning water is one of the main agents, which carries away soil particles.Soil erosion by water occurs by means of raindrops, waves, or ice.Erosion by water is termed differently according to the intensity and nature of erosion: RAINDROP erosion, sheet erosion, rill and gully erosion, stream bank erosion, landslides, coastal erosion, glacial erosion.Soil ErosionSoil erosion is the loosening and displacement of topsoil from the land due to the action of agents like WIND and water.Soil erosion in nature may be a slow process (geological erosion) or a fast process promoted by human activities like overgrazing, deforestation.Weathering and erosion lead to the simultaneous process of ‘degradation’ and ‘aggradation’.Erosion is a mobile process while weathering is a static process (there is no motion of disintegrated material except the falling down under the force of gravity).