nancy rogel eddie guadarrama. ● what is soil erosion ● types of erosion ● factors affecting...
TRANSCRIPT
SOIL EROSION Nancy RogelEddie Guadarrama
OUTLINE● What is Soil Erosion
● Types of Erosion
● Factors Affecting Erosion Rates
● Human Activities that increase Erosion Rates
● How to Prevent Erosion
WHAT IS SOIL EROSION● In agriculture, erosion refers to the
removal of a field’s topsoil due to natural forces of water and wind or through human activities such as tillage
● 3 stepso Soil detachmento Movemento Deposition
TYPES OF EROSION● Water
○ Splash○ Sheet○ Rill○ Gully○ Bank
● Wind○ Suspension○ Saltation○ Soil Creep
● Glacial○ Plucking○ Abrasion○ Freeze-thaw
WATER EROSION ● Splash Erosion: Direct movement of soil by the impact of water
droplets. Soil particles can be thrown up to 3 feet
● Sheet Erosion: Uniform removal of soil in thin layers from a large area due to impact from raindrops
● Rill Erosion: Small channels (<30 cm) carved out on a slope by running water
● Gully Erosion: Large channels (>30 cm) carved out by running water that cannot be removed by normal tillage equipment
● Bank Erosion: Saturated sides of running streams fall into moving water below
Source: http://www.cep.unep.org/pubs/Techreports/tr41en/Image11.gif
WIND EROSION● Suspension: The movement of fine particles into the
atmosphere over long distances due to strong winds
● Saltation: The movement of soil particles through short bounces along the surface, displacing additional particles with each impact. Primary source of wind erosion.
● Soil Creep: The rolling of larger soil particles across the surface, aided by the bouncing movements of saltating particles
Source: http://passel.unl.edu/Image/siteImages/Saltationscreencapture2-LG.gif
GLACIAL EROSION• Plucking: Glacial ice freezes into cracks in rocks and when
the glacier moves it pulls out rocks leaving a jagged surface •
Abrasion: When rock frozen to the base and the back of the glacier scrapes the bed rock
•Freeze-thaw: When water in the cracks of rocks freezes and expands. Over time, portions of rock are broken off
FACTORS AFFECTING EROSION RATES● Climatic Factors
● Vegetation
● Characteristics of Soil
● Topography
CLIMATIC FACTORSo Rainfallo Amount, Intensity and Frequency:o A greater percentage of the rainfall will become
runoff during periods of frequent rainfall. o This is due to high soil moisture or saturated
conditions.
CLIMATIC FACTORS● Temperature:
o Frozen soil is resistant to erosion
o Temperature affects organic matter
VEGETATION● Important physical factor influencing soil erosion.
● Vegetation binds the soil together which makes it more resistant to runoff.
● Organic matter is provided by vegetation which can slow down runoff.
● A dense, robust cover of vegetation is one of the best protections against soil erosion.
CHARACTERISTICS OF SOIL● Soil Texture:
o The size or combination of sizes of individual soil particles.
o Silt particles are most susceptible o Clay or Sand particles are less prone to erosion.
CHARACTERISTICS OF SOIL● Soil Structure:
o Soil particles get clumped together to form larger clumps and pore spaces.
o Structure influences both the ability to absorb water and its resistance to erosion.
TOPOGRAPHY● Slope Length:
o Longer Slopeo Base of the slope
● Slope Steepness & Surface Roughness:o Speed of runoff flow o Erosion rates increase if
the flow is fast.
HUMAN ACTIVITIES THAT INCREASE EROSION RATES
● Overgrazing
● Overcropping
● Deforestation
● Construction
OVERGRAZING● Occurs when plants are exposed to intese grazing.
● Animals can damage the soil surface by eating the vegetation
and compacting dry soil with their hooves.
● Soils with less vegetation become exposed and are more prone to water and wind erosion.
OVERCROPPING● This occurs when the land is being continuously cultivated with
no breaks in between crops.
● Humus Production is affected
● The soil dries out and is prone for wind and rain erosion with less humus.
DEFORESTATION● Deforestation leaves an open and exposed landscape after cutting
down large areas of forests.
● Nutrients and minerals are removed from the soil
● Areas are exposed to water and wind erosion.
CONSTRUCTION ● Construction often begins with by clearing the area of any plants
or other natural defenses against soil erosion.
● Construction also includes several tasks such as altering drainage patterns and compacting the soil.
HOW TO PREVENT EROSION● Terracing
o A sloped plane is cut into a series of successively receding flat surfaces
● Contour Farmingo Planes of land are constructed by cutting off the land according to its
contours.
● Cover crops
● Windbreakso Plant trees and shrubs along the edges of agricultural fields to help
protect the fields against wind erosion.
● Mixed-cropping
● Crop rotation
WORK CITEDhttp://www.kalkaskacounty.net/planningeduc0043.asp
http://en.wikipedia.org/wiki/Erosion#Factors_affecting_erosion_rates
http://lcgeography.preswex.ie/how-human-activities-can-accelerate-soil-erosion.html
http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/255153/fact-sheet-1-types-of-erosion.pdf
http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1086025423&topicorder=19&maxto=7
http://www.geography.learnontheinternet.co.uk/topics/glaciation1.html