Lecture54-56(2008)

Lecture54-56(2008) - WATER EROSION AND SOIL LOSS PREDICTION...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
WATER EROSION AND SOIL LOSS PREDICTION Chapter 15 in Introduction to Environmental Soil Ph ysics Erosion of soil by water and wind destroys good farm and forest land. Eroded soil/sediment is often a source of pollution to surface water. Erosion = removal of the nutrient-enriched topsoil, resulting in reduced soil production potential (productivity). Soil erosion by water may be divided into three modes: (1) detachment (2) trans port (3) de position - reduced overland flow velocity areas, zones: i.e., toe slope positions, stream channels, lakes, and reservoirs.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Factors Affectin g Detachment Raindro pim pact : Soil erosion has been correlated to the kinetic energy of raindrops. Kinetic energy (KE) of a raindrop, KE = 1/2 mv 2 , where m = mass of drop, and v = velocity of drop. Terminal, v, is proportional to the square of the radius of raindrop The KE of a given raindrop of mass, m is proportional to the 4th power of the radius of the drop--- ---if the radius doubles, the KE is increased 2 4 = 16 times. As rainfall intensity increases , drop size increase ,---thus the kinetic energy increases significantly because both mass of water and velocity of the drops increase. Raindrop impact is the major cause of particle detachment and suspension ---leading to erosion.
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
K.E. = ½ mv 2 K.E. - Kinetic energy of raindrop m - mass of raindrop v - velocity of raindrop Kinetic Energy of Raindrops F down F up F down = mg = D w 4/3 B r 3 g F up = Cf B r 2 ( D a v 2 / 2) D w 4/3 B r 3 g = C f B r 2 ( D a v 2 / 2) v 2 = 8/3 D w g r / C f D a C = 8/3 D w g (constant) C f D a v 2 = C r v " s r=r 1/2
Background image of page 4
K.E. = ½ mv
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 23

Lecture54-56(2008) - WATER EROSION AND SOIL LOSS PREDICTION...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online