The friction factor is affected by variations of fluid physical properties caused by variations in temperature and by the action of buoyancy forces. In rough channels the hydraulic resistance increases due to formation of vortices at the roughness elements leading to additional loss of flow specific energy. Three types of roughness can be distinguished: Natural roughness, which is formed as a result of long operation of pipelines.
Erosion by Glaciers. Like flowing water, flowing ice erodes the land and deposits the material elsewhere. Glaciers cause erosion in two main ways: plucking and abrasion. Both are illustrated at this link: [Insert a link to an animation showing how glaciers cause erosion by plucking and erosion.] Plucking is the process by which rocks and other sediments are picked up by a glacier.
Best Answer: Water flows where there is the least amount of resistance. Over time when this water carries a sediment load brooks, creeks and rivers are created. Your natural water way would be the area of least resistance.Drainage ditches are man-made they are not natural they are used to drain off fields but also used to redirect water so that it doesn't flood an area.Hope that helps.f I remember my geography right any water way was a natural waterway. The LA river is a natural waterway-though concrete. The Mississippi is a natural waterway though man has changed it over time.