LEC FINAL Flashcards
(158 cards)
1
Q
What are the process of soil erosion?
A
Detachment
Transportation
Deposition
2
Q
The detachment and movement of soil or rock by water,wind,ice, or gravity to an area of deposition.
A
Erosion
3
Q
The process by which the land surface is worn away by the action of wind, water, ice and gravity.
A
Soil erosion
4
Q
Two types of soil erosion?
A
Geological or natural erosion
Accelerated erosion
5
Q
Wearing away of the earth’s surface by water, ice or other natural agent’s under natural environment conditions.
A
Geological or natural erosion
6
Q
Erosion that much more rapid than normal, natural, geological erosion.
A
Accelerated erosion
7
Q
Two steps are recognized in accelerated erosion.
A
- Detachment
- Transportation
8
Q
Steps that are recognized in accelerated erosion where cause by freeze/thaw,wet/dry,flowing water,wind raindrops, human activity.
A
Detachment
9
Q
Steps that are recognized in accelerated erosion where cause by floating, rolling, dragging, splashing, human activity etc.
A
Transportation
10
Q
Process where raindrops soil sediments from the soil surface into the runoff.
A
Soil detachment by rainfall
11
Q
A process where the sediments from upslope to downhill direction, whether in rills, between rills, and sheet flow.
A
Entrainment or Transportation of sediments
12
Q
The process of sediments settling out under the action of gravity.
A
Sediment deposition
13
Q
True or false.
The rate depends on particle size, being rapid for sand and slow for.clay particles.
A
True
14
Q
What are the 3 important impacts of raindrops?
A
- It detaches soil-force of falling water.
- Beatings tend to destroy granulation at surface.
- Crusting leads to more runoff.
15
Q
Type of water erosion where due to the force of raindrops falling on bare or sparsely vegetated surfaces.
A
Splash erosion
16
Q
The particles are detached by the force of falling raindrops.
A
Splash erosion
17
Q
The soil rises into the air and maybe moved by gravity or wind or water down-slope.
A
Splash erosion
18
Q
It causes breakdown of soil aggregates.
A
Splash erosion
19
Q
It detaches soil particles that may clog soil pores → reduce infiltration →inceases runoff volume.
A
Splash erosion
20
Q
True or false.
The impact of water droplet dislodges and scatters soil particles.
A
True
21
Q
Type of water erosion where the soil particles are easily transported in a thin layer or sheet by flowing water.
A
Sheet erosion
22
Q
Type of water erosion where the sheet runoff is allowed to concentrate and gain velocity or energy, it will cut rills and gullies as it detaches more soil particles.
A
Rill and gully erosion
23
Q
Type of water erosion where it occurs along the banks of streams.
A
Stream bank erosion
24
Q
A
25
What are the factors affecting soil erosion?
1. Rainfall
2. Soil erodibility
3. Vegetation cover
4. Relief (Slope)
5. Human activities
26
This is the climatic element that mainly affects erosion in the humid tropics. In general, rainfall intensity (and not rainfall amount) is positively correlated to soil erosion if all other factors are held constant.
Rainfall
27
What are the affects of erosivity of rainfall?
-frequency
-intensity
-Duration
-Distribution
28
This refers to the vulnerability or proneness of the soil to erosion.
Soil erodibility
29
What are the properties affecting erodibility?
1.Soil texture
2. Soi structure
3. Organic matter
30
It is defined as the fineness or coarseness of soil particles. Soil erosion by raindrop impact is affected by the texture, which in turn also affects transportability.
Soil texture
31
True or false.
High sand content induces surface runoff and increases transportability but decreases detachability.
False. High clay content
32
True or false
Medium -textured soils (silt, silt loam, and loam) are more erodible than sandy and clayey texture.
True
33
True or false.
Hugh sand content gives a coarse texture, which allows water to infiltrate readily, reducing runoff.
True
34
True or false.
A relatively high infiltration rate coupled with resistance to transport by runoff results in a low erosion potential.
True
35
It is the arrangement of primary particles into aggregates (crumbs), affect soil erosion either directly by increasing infiltration or indirectly through the function of stable soil aggregates brought about by increased organic matter (OM) concentration.
Soil structure
36
True or false.
Soil structure influences the infiltration rate and the movement of water in a soil.
True
37
What is USDA stand for?
-United States Department of Agriculture (USDA)
38
It promotes aggregation leading to increased infiltration rate.
Organic matter
39
Binds soil particles to form water stable aggregates -it reduces soil erodibility and increases soils WHC.
Organic matter
40
True or false.
Vegetation cover affects the interception of rainfall by absorbing its kinetic energy and thus reducing runoff.
True
41
True or false.
- vegetation covers affect the retardation of erosion by decreasing runoff velocity;
-vegetation covers affects the improvement of aggregation and porosity and soil by roots and plant residue.
True
42
True or false.
-vegetation covers increased biological activity in the soil.
-vegetation covers affects the transpiration, which decreases soil moisture, resulting in increased storage capacity.
True
43
It shields the soil surface from the impact of failing rain.
Vegetation cover
44
It holds soil particles in place and it maintains the soil's capacity to absorb water.
Vegetation cover
45
It slows the velocity of runoff and it removes subsurface water through evapotranspiration.
Vegetation cover
46
True or false.
Both the slope steepness and slope length affect erosion and runoff behavior.
True
47
True or false.
Soil erosion increases at an increasing rate with increasing slope steepness while the amount of soil loss increases as the slope length increases.
True
48
What are the slope typography that affecting soil erosion?
-slope length
-slope gradient
-slope orientation
49
True or false.
As both slope length and gradient decrease, the velocity and volume of runoff increases, and the erosion potential is magnified.
False. Length and gradient increase
50
True or false.
Highly permeable soils are more prone to erosion by water since they can absorb water effectively.
False. Less
51
True or false.
Permeable soils also favour root proliferation and encourage Vegetation to grow.
True
52
53
This factors affecting soil erosion such as shifting cultivation, improper cultivation (tillage), deforestation, overgrazing, burning, road construction, urbanization, mining etc.
Human activities
54
Which of the following does not belong to the group when the tropical forest is cleared:
A.loss of original protective canopy cover.
B.interrupted deposition of plant biomass on and in the soil.
C.decrease amonuiof rainfall hitting the ground, with increased kinetic energy.
D. Decreased topsoil organic matter.
C. decrease amonuiof rainfall hitting the ground, with increased kinetic energy.
55
This is also known as soil blowing.
Wind erosion
56
This may range from a slight disturbance of the soil surface over a small area to the huge dust storms that sweep across large areas, remove tons of soil, and constitutes a major catastrophe.
Wind erosion
57
What are the forms of wind erosion?
1. Destrusion
2. Abrasion
3.
58
The wearing away of rocks and soil projections by fine particles carried in suspension. Forms the large rocks carved into grotesque shapes in deserts.
Destrusion
59
A similar action takes place close to the ground where the moving particles are larger and bouncing along over the surface.
Abrasion
60
Forms of wind erosion by which materials are carried away:
1. Extrusion
2. Efflution
3. Efflusion
61
The rolling away by large particles.
Extrusion
62
The removal of very fine particles.
Efflution
63
Particles of intermediate size move off downwind into bouncing action call saltation.
Efflusion
64
What are the types of particles movement by wind action?
a. Suspension
b. Creep
c. Saltation
65
It is the movement by very fine particles, mainly less than 0.1 mm diameter.
Suspension
66
It is the rolling movement particles ( 0.5 to 2 mm in diameter)
Creep
67
It is the bouncing movement of particles (0.5 mm to 0.5 mm in diameter).
Saltation
68
Determined whether it is on-site impacts or off-site impacts.
-Loss of deep fertile surface soil and consequential loss of soil fertility and productivity.
On-site impacts
69
Determined whether it is on-site impacts or off-site impacts.
- accumulation of abnormal quantities of silt, sand and gravel in the agricultural field and streams.
Off-site impacts
70
Determined whether it is on-site impacts or off-site impacts.
-Loss of organic matter
On-site impacts
71
Determined whether it is on-site impacts or off-site impacts.
- accumulation of sediments impairs drainage.
Off-site impacts
72
Determined whether it is on-site impacts or off-site impacts.
- Deterioration of soil property- moisture capacity.
On-site impacts
73
Determined whether it is on-site impacts or off-site impacts.
-Cause rapid filling of irrigation canals, stream channels, reservoirs (siltation).
Off-site impacts
74
Determined whether it is on-site impacts or off-site impacts.
-Damage to water and power supply, irrigation, drainage, navigation, and flood control developments.
Off-site impacts
75
Determined whether it is on-site impacts or off-site impacts.
-Deterioration of soil property- moisture capacity.
On-site impacts
76
Determined whether it is on-site impacts or off-site impacts.
- Decreased sustainability for agriculture use, reduced crop yield.
On-site impacts
77
What are the erosion prevention principle:
1. Prevent detachment
2. Limit transport
3. Reduce runoff, increase infiltration, roughen surface and reduce slope.
-promotes on-site deposition
78
Types of erosion control /prevention measures?
1. Structural/mechanical measures
2. Cultural measures
79
Types of mechanical measures/control?
1. Riprap
2. Terracing
3. Bioengineering
4. Sediments traps
5. Retention ponds
80
Large angular rocks may be laid at the bottom or side of channels where high-water velocities may be expected.
Riprap
81
Designed to limit/prevent detachment of soil particles at the bottom or side of channels.
Riprap
82
Stairs-like surface manipulation to reduce down-slope runoff velocity and encourage retention of sediments.
Terracing
83
Use of vegetation to protect channels, reduce runoff velocity and trap sediments.
Bioengineering
84
Traps that are designed to slow-down runoff and trap sediments.
Sediment traps
85
It maintains and increases organic matter content and improves oil physical condition, suppresses weeds and conserves water.
Cover cropping
86
When plowed under and incorporated into the soil, cover crops may be referred to as green manure crops.
Cover cropping
87
This technique involves either sequential cropping, the growing of 2 or more crops a year in sequence, intercropping the growing of 2 or more crops in the same piece of land at the same time.
Multiple cropping
88
Anu material such as straw, sawdust, leaves, plastic film, loose soil, etc. that is spread or formed upon the surface of the soil to protect the soil and/or plants roots from the effects of raindrops, soil crusting, freezing, evaporation, etc.
Mulching
89
Any tillage sequence that reduces loss of soil or water relative to conventional tillage, generally leaves at least 30% of the soil surface covered by residues.
Conservation tillage
90
What are those practices that are designed to prevent/limit detachment while the area could still be devoted to agriculture.
1. Minimum tillage
2. Strip tillage
3. Ridge tillage
4. No tillage system
91
The minimum use of primary and/or secondary tillage necessary for meeting crop production requirements under the existing soil and climatic conditions, usually resulting in fewer tillage operation than for conventional tillage.
Minimum tillage
92
Preparation of seedbed by conditioning the soil along narrow strips in adjacent to seed rows.
Strip tillage
93
A tillage system in which ridges are reformed a top the planted row by cultivation, and the ensuing row crop is planted into ridges formed the previous growing season.
Ridge tillage
94
Planting of close growing grasses and legumes to cover and protect the surface of the soil.
Cover cropping
95
A procedure whereby a crop is planted directly into the soil with no primary or secondary tillage since harvest of the previous crop; usually a special planter is necessary to prepare a narrow shallow seedbed immediately surrounding the seed being planted.
No till
96
Plowing, harrowing and furrowing across the slope of the land or effective in minimizing soil erosion on gentle slopes reducing soil loss up to 50%.
Contour Cultivation
97
Occurs when conditions are favorable for the detachment and transportation of soil material.
Erosion
98
What are the principles in reducing the susceptibility of the soil to erosion?
-limit detachment
-limit transport
-reduce runoff, increase infiltration, roughen the soil surface,
99
Construction of the earthen embankment adjusted to soil and slope to control runoff.
Terracing
100
It is designed to control runoff in areas of high rainfall and conservation of water in low rainfall areas.
Terracing
101
Traps sediments in the drainage ditches built along the terrace.
Terracing
102
Generally needed croplands that slope as much as 2%
Terracing
103
It is traditionally practice in Cordillera areas.
Terracing
104
A shallow ditch that runs horizontally across the slope following the contour of the land.
Contour canals
105
Constructed on farmland where the soil is reasonably deep.
Contour canals
106
Generally needed on croplands that slope as much as 2%
Terracing
107
The slope is longer than 22 meters. In every absorptive soil, the terraces are built and water can stand soaking into the ground.
Terracing
108
Should be constructed on all slopes 5-25%
Contour canals
109
Should more or less be about 5 cm wide and 30 cm deep.
Contour canals
110
True or false.
The main purpose is to hold water in a field, thereby increasing soil moisture and groundwater supply and to drain water away from the field without necessarily changing the soil.
True
111
True or false.
Small compartments of water can also help recharge ground water aquifers.
True
112
They are more permanent structures that are built in areas with large rocks.
Contour rock walls
113
Large rocks are used for the base and outside the wall, while smaller rocks are filled in the middle.
Contour rock walls
114
It is the material to use contour lines.
A-frame
115
Rock fitted/piled on the top of each other to form a retaining wall.
Riprap
116
Use of rectangular wire crates filled with stones acting as a retaining wall. These are flexible, absorbent, and economical in places where stones are abundant.
Gabions
117
Protects the soil from the impact of raindrops. Done by covering the whole area with a protective layer of concrete or rocks.
Riprap
118
Used to stabilize the hillside, road banks, and stream banks.
The wall thickness may vary ¼ to meter.
Riprap
119
-Involves the use of stones as walling material.
Stkned are collected and piled along the contour to form high walls.
Stone walls
120
Depression on the farm, especially in heavily gullied areas.
Can be utilized as farm ponds Tk store water and to minimize the potential runoff.
Farm ponds/water impounding dams
121
-protects against drought.
-improves food production (crop,fish,fruits trees and etc. )
-promotes conservation and ecological balance, easy to construct.
Farm ponds/water impounding dams
122
Simple structure that can stop gully erosion by slowing down the water flow in the drainage system.
Check dams/drop weirs
123
-it promotes the deposition of nutrient-rich, high fertile sediments.
-also barrier that stops the flow of water.
Check dams/drop weirs
124
-Constructed when the grassed waterways are too long.
Check dams/drop weirs
125
What are the types of check dams?
-Masonry check dams
-Rock/stone check dams
-Earth check dams
-pole/log check dams
-brushwood check dam
126
127
128
These are small channels / canals that run vertically on the slope.
Used for removal of excess water from.rainfall and underground seepage.
Drainage system/canals
129
Soil losses or relative erosion rates estimates are important in evaluating management practices meant to decrease soil losses.
Soil loss Equation Measurement
130
It is usually the most fertile, containing the plant nutrients, humus, and fertilizers.
The soil lost through water erosion
131
A method of estimating soil loss was developed from1945-1965 based on the statistical analyses of filed plot data from small plots in many states in the U.S.
USLE - Universal Soil Loss Equation
132
This equation was developed to include factors that affect soil losses and application throughout the world.
USLE
133
Useful for determining conservation measures adequacy in farm planning and predicting non-point sediments losses. The Ave. annual soil loss equation was determined by Wischmeier and Smith (1978) as cited by Swab et Al. (2006).
Universal Soil Loss Equation
134
What are the soil loss measurement / prediction tools
-USLE - Universal Soil Loss Equation (1978)
- RUSLE- Revised USLE (1997)
135
1 acre is equal to _____
0.405 ha
136
The following stands for :
A= R x K x LS x C x P
A= estimated soil loss in tons. per acre / per year.
R = rainfall-runoff erosivity factor
K = soil erodibility factor
L= slope length factor
S=slope steepness factor
C = cover -management factor
K= support practice factor
137
It can estimate only sheet and rill erosion.
USLE and RUSLE
138
It can
139
Refers to the amount of eroded material that passes a designated point at the outflow end of a plot, field, channel, or watershed (catchment).
Sediment yield
140
Represents the driving force of sheet and rill erosion.
Consider total rainfall, and distribution
R Rainfall erosivity factor
141
Represents both susceptibility of soil to erosion and the rate of runoff, as measured under the standard unit plot condition.
K soil erodibility factor
142
Large raindrops are more erosive
High rainfall rate proved more means to transport detached particles.
R Rainfall erosivity factor
143
It is influenced by infiltration capacity and structural stability
K soil erodibility factor
144
This is the topography factor
LS-length and steepness factor
145
It includes the
- cover cropping
- tillage practice/soil management
C- cover -management factor
146
Adaptation of support practices on steep or long slopes as means of erosion control.
P= support practice factor
147
Example of practices in P factor:
Contour tillage
Contour strip tillage
Terrace system
Grassed waterways
148
What are the factors affecting Soil Loss Estimates ?
Soil erodibility
Climate
Soil roughness
Field length
Vegetation
149
Determined by the percentage of dry soil fractions greater than 0.84 mm in diameter, which is inversely related to soil loss. The land slope is also considered.
Soil erodibility
150
Relative climate percentage have been developed based on wind velocity and surface soil moisture.
Climate
151
It is natural or artificial roughness of ridges or small undulations, but not for clods or vegetation. Ridges about 2-5 inches in height are the most effective in reducing soil loss.
Soil roughness
152
This factor is based on the median travel distance across the ending surface, and this includes the magnitude, prevailing wind direction, and ratio of wind erosion forces parallel to the prevailing wind direction to those perpendicular to the prevailing wind direction.
Field length
153
This depends on the kind of vegetation, its orientation and height, and the amount of.surface residue. The height, density, and surface area of the vegetation effectively reduce wind velocity and erosion.
Vegetation
154
Refers to the capacity that must be provided in a structure that must carry runoff.
Design runoff ratr
155
Refers to the total volume of runoff coming from the watershed for a design flood.
Runoff volume
156
Refers to the annual runoff amount. Methods of estimating the minimum water yield make use of the storm flow records.
Water yield
157
Refers to the amount of eroded material that passes at a designated point at the outflow end of a plot, field, channel, or watershed.
Soil losses or sediment yield
158
Is an important
