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.
In the summer it is good to mulch the lawn (don't vacuum up the grass) so that you can spend less on water. 8. Aerate your lawn at least once in the spring and again in the fall for a green lawn. The process of aeration makes small holes in the surface of your lawn, allowing water, nutrients and air access to the roots. The water will be less likely to evaporate, and there are generally lower winds. 2  Watering the grass in high wind can cause the grass to dry before the water penetrates the soil. 3  For a green lawn, water your grass until the water penetrates at least 6 inches (15.24 cm) deep into the soil.