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.
Water Erosion. Water is the most important erosional agent and erodes most commonly as running water in streams. However, water in all its forms is erosional. Raindrops (especially in dry environments) create splash erosion that moves tiny particles of soil.he process known as weathering breaks up rocks so that they can be carried away by the process known as erosion. Water, wind, ice, and waves are the agents of erosion that wear away at the surface of the Earth. Water is the most important erosional agent and erodes most commonly as running water in streams.