Landforms that result from erosion by water flowing on land surfaces. This water may concentrate in channels as streams and rivers or flow in thin sheets and rills down slopes. Essentially all land surfaces are subjected to modification by running water, and it is among the most important surface processes. Valleys are cut, areas become dissected, and sediment is moved from land areas to ocean basins. With increasing dissection and lowering of the landscape, the land area may pass through a series of stages known as the fluvial erosion cycle.