SSM chapter 18 and 19

what are some of the consequences of erosion
removal of topsoil(which contains plant material and organic matter), thinning of soil profile, gullies cut feilds. The runoff then pollutes nearby lakes with nutrients and pesticiides.
what are some of the costs of erosion?
what are the two parts of the cost of ersion?
1.costs to the farmer and consumer of production losses, and
2.costs to the public of pollution and sedimentation.
costs reange from an estimated 40 million to 27 billion. offsite damages are generally significantly larger, ranging from 3.1 to 17 billion per year
what is the erosion equation?
erosion is equal to E=(1/2)mv^2
what are some qualities of soil that determine the rainfall erosiveness?
texture and structure, slope, surface roughness, soil cover
splash erosion
the direct movement of soil by splashing.
sheet erosion
the removal of a thin layer of soil in a sheet due to water.
rill erosion
many small channels formed on a slope by water, like a miniature river.
ephemeral gully erosion
ephemeral gullies are large rills. The channel is small enough that tillage equipment can largely fill it in , but not completely.
gully erosion
most visible type of erosion, caused by deep channelization by running water.
what are the five types of water erosion
gully erosion, ephemeral gullies, rill erosion, sheet erosion, splash erosion.
concentrated flow
the combination of both ephemeral and gully erosion, in which water forms into channels. erosive energy is focused, and soil can be carried off the field.
universal soil loss equation
main tool for estimating soil erosion rates, but only predict sheet and rill erosion, and not ephemeral or gully erosion. Thus equation underestimates soil loss.
What is the USLE equation for soil loss?
A=RKLSCP, where a is the amount of tonnes of soil lost each year.
Understand how to use the equation.
what is the erosion index?
EI=(RKLS/T). Refer to other slide to see what variables refer to.
what does R, K, L, S, C, and P stand for?
r is rainfall and runoff factor, based on total erosive power of storms during and average year.
K
soil erodability factor(texture, structure, organic matter content)
LS
Slope factor. they are two separate factors but can be treated as one.
C
Cover and management factor. C comares cropping practices, residue management, and soil cover to the standard clean fallow plot.
P
support practice factor.
What are the four actions that can be done to control water erosion?
1.reduce raindrop impact to lesson soil detachment.
2. Reducing of slowing runoff
3. carrying excess water off the field safely by use of grass waterways or tile outlets.
4.filter soil particles out of running water
contour tillage
tilling on the contour, then planting and following the same contour to lessen the runoff.
strip cropping
alternating a dense cover crop with a not as dense cover crop along thw contour in order to prevent runoff.
grassed waterway
a shallow, sodded, wide ditch that runs down a slope. their main purposes are:
1.prevent gullying
2.collect excess water from tillage contours
3. serve as outlets for terraces.
conservation buffer
strips of permanent vegetation that slow overland flow and act as living filters to remove sediment, nutrients, and pesticides.
contour buffer strip
strips of permanent vegetation planted on the contour between strips of cultivated crops(similar to contour strip cropping, just with grass as one of the crops)
filter strips
lie along the downhill edge of a feild, and work to filter sediment out of runoff from a feild before it can leave.
riparian buffers
strips of permanent vegetation along streams, wetlands, etc to protect water quality from feild runoff.
when is a terrace used?
when other measures fail to reduce erosion adequately.
what are the two typs of terraces and when are they used
level and graded; level is used when soil is permeable enough to allow water to seep in once captured by the terrace.
In the other hand, graded terrace is used when water CANNOT soak in enough. They might be drained underground of slope towards the waterway.
what are the four uses of diversions
1. protecting feilds from runoff flowing from higher elevations
2. diverting water away from active gully heads
3.diverting water from feed lots, farmsteads, or other sensitive areas,
4. in residential housing, diverting water away from homes.
boundary layer
a very thin layer still air that covers a soil surface, but larger rocks stick up above the layer.
saltation
the process of grain of a grain of sand jumping into the air, coming back down, knocking silt in to the air from its impact.
suspension
when dust rises into the air and is carried for long distances.
surface creep
when sand between the size of .02 and .04 inches are too large to be kicked into the air, they roll along the ground
what are some possible ways to reduce wind erosion?
till at right angles to the wind
2.use conservation tillage or leave crop residue on the soil surface
3. keep soil covered with as much vegetation as possible.
moiste soil to keep it bound together better.
plant windbreaks such as trees and shrubs
plant the most critical areas to permanent grasslands or other vegetative cover.
Brown feilds
abandoned idled, or underused industrial or commercial facilities where redevelopment is hampered by real or perceived contamination.
bioremediation
the use of living things to reduce pollution.
what are some ways to control construction erosion and sedimentation?
1. Keep disturbed areas small.
2.protect disturbed areas.
3.keep runoff velocities low.
4. divert runoff away from disturbed sites
5.retain sediment on site.
erosion control blanket
blankets that can be rolled over bare soil. They are biodegradable.
hydromulching
involves blowing mixtures of water, finely chopped straw, and seed over disturbed areas. vegetation should grow from seed.
rip rap
covering soil with concrete.
check dams and wattles
bundles of straw placed in an area where runoff is happening in an attempt to reduce sediment load.
silt fence
a dense mesh fabric buried partially underground and attached to posts to create a fence which strains the sediment load from water as it passes through.
retention ponds and sediment basin
places where sediments are taken and settle out.
low impact development or zero runoff development
another option which involves leaving the water on site and allowing it to filter into the soil, using the water for irrigation rather than disposal.
swales
a shallow ditch where water is carried to in developments.
bioswale
a swale with deep porous soil and dense vegetation that slows runoff, promotes infiltration, and traps sediment.
recharge basin
retention ponds that are designed to promote infiltration rather than simply hold water.
rain garden
a depression in the yard that is meant to absorb the rain an drunoff.
green roofs
beds of vegetation planted on rooftops. can either be extensive(little) or intentsive (a lot)