Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 1 of 56
5.4 Land degradation --Soil erosion
(1) Types of land degradation
(2) Classification of soil erosion
(3) Climate and soil erosion
(4) Soil erosion models
(5) Erosion and productivity
(6) Rainfall factor for soil erosion model
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 2 of 56
(1) Types of land degradation
? Desertification
? Soil erosion,water erosion and wind
erosion
? Salinization/alkalization
? Soil pollution
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 3 of 56
(2) Classification of soil erosion
Zachar,1982,By erosive agents
? Water erosion
? Wind erosion
? Earth erosion
? Glacial erosion
? Anthropogenic/accelerated erosion
? Organic,soil flow,snow
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 4 of 56
(2) Classification of soil erosion
Zachar,1982,By erosion form
Precipitation/water erosion
? Surface erosion
? Underground erosion
? River erosion
? Lake and sea erosion
Wind erosion
? Deflation
? Wind corrasion
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 5 of 56
(2) Classification of soil erosion
Precipitation/water erosion
? Surface erosion (American)
? Sheet,gully,stream/river (Ayres,1936)
? Sheet,rill,gully,rock (Bennett,1939)
? Sheet,internal,channel (rill,gully,
stream) (Kohnke and Betrand,1959)
? Interill,rill,ephemeral gully,gully
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 6 of 56
(2) Classification of soil erosion
? Precipitation/water erosion (Russians)
? Washing,wearing (Kozmenko,1954)
? Sheet(rill),gully (Sobolev,1948)
? Normal,accelerated (surface,rill,linear/gully Sus,
1949)
? Water erosion (French)
? Washing,downpour,sheet,layer or strip,rill,wearing
? Mass removal,landslides,underground,mud flows,
creeping
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 7 of 56
(2) Classification of soil erosion
By erosion intensity
? Harmless/normal erosion
? Compensative erosion
? Tolerance erosion
? Harmful erosion (sheet,gully)
? No erosion,insignificant erosion
? Slight erosion
? Moderate erosion
? Severe erosion
? Very severe erosion
? Catastrophic erosion
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 8 of 56
(2) Classification of soil erosion
Compensative erosion
? Erosion in which the rate of destruction equals that of soil
formation
? Soil formation rate
90cm thick soil layer,16,000a; 1cm/178a (Kohnke and Bertrand,
1959)
2-3cm/200-1000a,1cm/240a (Bennett,1955)
1cm/100a (Kukal,1964)
? Soil loss rate
Normal erosion,0.1-0.6 t/acre a (0.25-1.48t/ha a,25-128t/km2 a)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 9 of 56
(2) Classification of soil erosion
Permissible/tolerance erosion
1.24-14.84t/ha a (Smith and Stamey,1965)
6.75 t/ha a (Kohnke and Bertrand,1959)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 10 of 56
(2) Classification of soil erosion
By erosion development
? Depending on different erosion form
? Sheet
? Gully
? Intrasoil wash
? Tunnel
? Darst
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 11 of 56
(2) Classification of soil erosion
? Classification of eroded soil
on arable land,on pastures,forest soil,by wind
erosion
? Classification of erosion remains
relics,rudiments,selective remains,inhibited
remains
? Classification of sediments
according to,erosion factors,buried soil
? Classification of eroded land
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 12 of 56
(3) Climate and soil erosion
Climate applications
? Ptolemy,climate zone
? Ecological work,
Climate and plant distribution (Von Humboldt,
1799)
Climate and soil genesis and distribution
(Dokutschajeff,1879)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 13 of 56
(3) Climate and soil erosion
Climate applications
? Geomorphologic work,land form,
physiographc processes
? Soil erosion,related to all these factors-
Climate,wind velocity,rainfall intensity,
temperature,etc,
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 14 of 56
(3) Climate and soil erosion
Soil erosion causing factors
? Climate
? Climate complex
? Individual climate factors
? Soil
? vegetation
? landform
? Soil conservation practices
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 15 of 56
(3) Climate and soil erosion
Individual climate factors--Precipitation
? Individual storm
? Average quantities
? Example
100mm/month
one 5-hour storm
ten 10mm/event storms
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 16 of 56
(3) Climate and soil erosion
variables
? Intensity
? Duration
? Amount,determined by intensity and
duration
? Types,storms event,seasonal distribution
? Time-area-intensity relationships
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 17 of 56
(3) Climate and soil erosion
Individual climate factors
? Wind
Velocity/Soil protection
Potentially an agent of erosion in all climates
not only arid semi-arid climates
? Temperature
Weathering processes
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 18 of 56
(3) Climate and soil erosion
Climate complex– climate and normal erosion
? Wet and humid regions– protected by forest
? Subhumid lands– protected by tall prairie grasses
? Semiarid areas-- protected by short grasses
? Deserts-- protected by desert shrubs partially
? Regards to erosion–
Greatest natural weakness lies on the drier margins
of semiarid climate and within arid regions
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 19 of 56
(3) Climate and soil erosion
Climate complex– climate and accelerated
erosion
? Since baring the soil allows the climatic elements
to operate to their fullest capacity,climate
becomes extremely important in considering
accelerated erosion,
? Where rainfall intensities are highest and
rainstorm durations are at a maximum,gullying
and sheet washing cause the greatest damage,
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 20 of 56
(3) Climate and soil erosion
Climate complex– climate and accelerated
erosion
? Wet and humid regions–
Potentially at maximum rate where the land
has been bared
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 21 of 56
(4) Soil erosion models
? Classification
Empirical models
Dynamic/process-based models
? Purpose
Simulating soil loss and sediments
Evaluating soil and water conservation
practices
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 22 of 56
Empirical soil erosion models
? Larger time scale,
month
half-month
? Statistical relationships
? Soil loss from slope field
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 23 of 56
An example for
empirical soil erosion models
Multiply method
? USLE,Universal Soil Loss Equation
RUSLE,Revised Universal Soil Loss
Equation
? CSLE,Chinese Soil Loss Equation
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 24 of 56
USLE/CSLE
A=RKLSCP
? Rainfall erosivity factor（ R）
? Soil erodibility factor（ K）
? Slope length and gradient factor（ LS）
? Crop and management factor（ C）
? Practice factor for soil conservation (P)
? In CSLE,CP=BET
? BET,Biological,engineering,tillage practices
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 25 of 56
Process-based soil erosion models
? Smaller time scale,daily/hourly
? Processes of soil erosion
? Statistical relationships for some
parameters and processes based on
experiments
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 26 of 56
Process-based soil erosion models
WEPP (USA)
water erosion prediction project
EROSUM (EU)
European Soil Erosion Model
LISEM (Netherlands)
Limburg Soil Erosion Model
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 27 of 56
(5) Erosion and productivity
? Soil loss estimation
Weight of soil loss W in t/ha a
Depth of soil loss d in mm/a,
d=W(weight)/B (soil bulk density)
B,bulk density in t/ha mm
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 28 of 56
(5) Erosion and productivity
? Productivity losses
减产率, y=f(d)(%)
土层厚度修正, (d/Da)*100%
土壤寿命估算, Da/d
d,annual soil loss in mm/a
Da,total soil depth in mm
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 29 of 56
(6) Rainfall factor for soil erosion model
? Rainfall erosivity for USLE
? Estimation of rainfall erosivity
? Rainfall erosivity for CSLE
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 30 of 56
Rainfall erosivity for USLE
R=EI30
? R-- EI parameter for one storm,in MJ
mm/h ha
? E-- total storm energy,in MJ/ha
? I30-- the maximum 30-min intensity,in
mm/h
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 31 of 56
Rainfall erosivity for USLE
Rave=(1/N)?? (? (EI30))
? Rave-- average annual erosivity,in MJ
mm/h ha a
? N-- number of years
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 32 of 56
Rainfall erosivity for USLE
E=?(e*p)
? e-- kinetic energy in unit rainfall,in
MJ/ha mm
? p-- breakpoint rainfall amount,in mm
e=0.119+0.0873log10(i) i<=76mm/h
e=0.283 i >76mm/h
? i-- breakpoint rainfall intensity,in mm/h
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 33 of 56
Estimation of rainfall erosivity
R- average annual erosivity (MJ·mm/(ha·h·a)
P- the 2-yr frequency,6-h rainfall amoutn(mm)（ Wischmeier 1974）
Arnoldus,R- annual erosivity(t?m?cm?ha-1?h-1?yr-1)
pi- average monthly rainfall（ mm）
P- average annual rainfall（ mm）
F-modified Fournier index
17.20 0 4 2.0 PR ?
PpF
i
i /)(
12
1
2?
?
?
50.12 6 4.0 FR ?
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 34 of 56
Estimation of rainfall erosivity
Yu(Australia),
R-erosivity(MJ?mm?ha-1?h-1?yr-1)
P- annual precipitation(mm)
F- modified Fournier index
61.10438.0 PR ? 41.182.3 FR ?
or
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 35 of 56
Estimation of rainfall erosivity
Renard(USA),
R- annual erosivity(MJ?mm?ha-1?h-1?yr-1)
P- average annual rainfall（ mm）
F- modified Fournier index
6 1 0.10 4 8 3 0.0 PR ?
20 0 4 1 0 5.02 1 9.18.5 8 7 PPR ???
8 4 7.17397.0 FR ?
24 7 7 0.00 8 1.677.95 FFR ???
P<850mm
P>850mm
F<55mm
F>850mm
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 36 of 56
Estimation of rainfall erosivity
Mikhailova
R- annual erosivity（ MJ?mm?ha-1?h-1?yr-1）
P- average annual rainfall (mm)
E- elevation（ m）
EPR 7 1 9 0.20 0 0 1.73.6 9 9－ ???
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 37 of 56
Estimation of rainfall erosivity
Richardson,
Ri- half-month erosivity for the ith half-
month(MJ?mm?ha-1?h-1?yr-1)
k- days for the ith half-month
Di- rainfall for the jth day in the ith half-month
（ mm）
?
??
?
?
k
1j
DiRi
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 38 of 56
Estimation of rainfall erosivity
黄炎和等,
R- annual erosivity（ J?cm?m-2?h-2?y-2）
Pi≥ 20- monthly rainfall only larger than 20mm
（ mm）
? ?? 12 5 6 8 2.1200199.0i iPR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 39 of 56
Estimation of rainfall erosivity
吴素业,
R- annual rainfall（ J?cm?m-2?h-2?y-2）
Pi- monthly rainfall（ mm）
?? 12 6295.10 1 2 5.0
i
iPR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 40 of 56
Estimation of rainfall erosivity
周伏建等,
R- annual erosivity（ J?cm?m-2?h-2?y-2）
Pi- monthly rainfall（ mm）
?
?
??? 12
1
3046.06398.2
i
iPR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 41 of 56
Estimation of rainfall erosivity
马志尊,
R- annual rainfall（美制单位）
P- annual rainfall（ mm）
Pi - monthly rainfall （ mm）
?
?
?? 12
1
8188.0)(5.1 2102157.1
i
L o g pipR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 42 of 56
Rainfall erosivity for CSLE
? A threshold for erosive rainfall
? Rainfall erosivity estimation
? Seasonal distribution of rainfall erosivity
? Isoerodent map for China
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 43 of 56
Research problems
? A threshold for erosive rainfall
different
but no reason and evaluation
? Rainfall erosivity index,EI30
data limited
complicated calculation
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 44 of 56
Research problems
? Seasonal distribution of rainfall erosivity
much data should be used for climate diversity
? Isoerodent map for China
much data should be used for complicated
environment
simplifying calculations
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 45 of 56
A threshold for erosive rainfall
Method
? More than 300 events during 1961-1969
? Erosive rainfall erosivity = non-erosive
erosivity
? Assessment index,3
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 46 of 56
A threshold for erosive rainfall
Results
? Rainfall amount,12mm
? Average rainfall intensity,0.04mm/min
? Peak rainfall intensity for 30-min,0.25mm/min
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 47 of 56
Rainfall erosivity estimation
? EI30－ Rainfall process data with break
point intensity
? PI10－ Rainfall event data with amount and
peak intensity for 10-min
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 48 of 56
Rainfall erosivity estimation
? 12 plots 214 plot-year data,PI10
? 14 weather station 1142 rainfall event data,
EI30＝ 0.1773（ PI10） R2 ＝ 0.902
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 49 of 56
Rainfall erosivity estimation
Scatter between PI10 and EI30 Index
0
500
1000
1500
2000
2500
3000
3500
4000
0 5000 10000 15000 20000
PI
10
(mm.mm.h
-1
)
EI
30
(MJ
·
mm
·
ha
-1
·
h
-1
)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 50 of 56
Seasonal distribution of rainfall erosivity
Methods
? 104 station-year data for both daily and
event data
Rhalf-mon=0.184 ?PdI10d
? 70 station daily data for classifying seasonal
distribution of rainfall erosivity
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 51 of 56
Seasonal distribution of rainfall erosivity
Results
? 19 groups for China
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 52 of 56
Isoerodent map for China
? USA,1965,EI30
1978,EI30, 27.37P2.17
1997,EI30, 1.0667（ EI） 15
? China,?PdI10d,70 stations
a?Pdb,661 stations
a?Fmb,about 1200 stations
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 53 of 56
Distribution of soil erosion experiment stations and
weather stations
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''
) Daily rainf all
Rain fal l p rocess
Rain fal l in ten sit y
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 54 of 56
Isoerodent map for China
--using daily rainfall data of 616 stations
1
0
0
0
1 0 0
0 0
8
0
0
0
500
2
0
0
0
南昌
郑州
兰州
西安
太原
南京
南宁
长沙
武汉
贵阳
重庆
成都
6
0
0
0
100
130120
250
哈尔滨
呼和浩特
沈阳
1 0
0 0
0
银川
4
0
0
0
2
0
0
0
6
0
0
0
6 0 0
0
8 0 0
0
500
1 0 0
0 0
1
5
0
0
0
2
0
0
0
4
0
0
0
6 0 0
0
昆明
拉萨
乌鲁木齐
西宁
500
4
0
0
02
0
0
0
500
1
0
0
0
100
100
100
500
4
0
0
0
100
100
100
250
1
0
0
0
40
50
海口1
0
0
0
08
0
0
0
250
100
110
1
5
0
0
0
1009080
30
20
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 55 of 56
Isoerodent map for China
--using annual rainfall data of 2180 stations
15
0 00
海口
15
0 00
2000
20
0
0
10
0
00
1000
6000
8000
20
0
0
250
500
60
0 0
10
0
0
40
0
0
哈尔滨
沈阳
南昌
南京
武汉
西安
太原
郑州
呼和浩特
南宁
成都
重庆
长沙
130110 120
80 90 100
20
0
0
500
10
0
00
60
0
0
80
0
0
40
0
0
拉萨
100
250
50
10 0 0
昆明
80 0 0
兰州
银川
西宁
100
6000
4000
100
250
250
20
0
0
1000
2000
乌鲁木齐
250
250
500
10
0
0
500
500
250
30
100
40
250
250
80 0 0
10
0
00
20
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 56 of 56
Thanks!
2012-3-21 Assessment of Climate/Change Impacts 1 of 56
5.4 Land degradation --Soil erosion
(1) Types of land degradation
(2) Classification of soil erosion
(3) Climate and soil erosion
(4) Soil erosion models
(5) Erosion and productivity
(6) Rainfall factor for soil erosion model
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 2 of 56
(1) Types of land degradation
? Desertification
? Soil erosion,water erosion and wind
erosion
? Salinization/alkalization
? Soil pollution
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 3 of 56
(2) Classification of soil erosion
Zachar,1982,By erosive agents
? Water erosion
? Wind erosion
? Earth erosion
? Glacial erosion
? Anthropogenic/accelerated erosion
? Organic,soil flow,snow
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 4 of 56
(2) Classification of soil erosion
Zachar,1982,By erosion form
Precipitation/water erosion
? Surface erosion
? Underground erosion
? River erosion
? Lake and sea erosion
Wind erosion
? Deflation
? Wind corrasion
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 5 of 56
(2) Classification of soil erosion
Precipitation/water erosion
? Surface erosion (American)
? Sheet,gully,stream/river (Ayres,1936)
? Sheet,rill,gully,rock (Bennett,1939)
? Sheet,internal,channel (rill,gully,
stream) (Kohnke and Betrand,1959)
? Interill,rill,ephemeral gully,gully
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 6 of 56
(2) Classification of soil erosion
? Precipitation/water erosion (Russians)
? Washing,wearing (Kozmenko,1954)
? Sheet(rill),gully (Sobolev,1948)
? Normal,accelerated (surface,rill,linear/gully Sus,
1949)
? Water erosion (French)
? Washing,downpour,sheet,layer or strip,rill,wearing
? Mass removal,landslides,underground,mud flows,
creeping
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 7 of 56
(2) Classification of soil erosion
By erosion intensity
? Harmless/normal erosion
? Compensative erosion
? Tolerance erosion
? Harmful erosion (sheet,gully)
? No erosion,insignificant erosion
? Slight erosion
? Moderate erosion
? Severe erosion
? Very severe erosion
? Catastrophic erosion
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 8 of 56
(2) Classification of soil erosion
Compensative erosion
? Erosion in which the rate of destruction equals that of soil
formation
? Soil formation rate
90cm thick soil layer,16,000a; 1cm/178a (Kohnke and Bertrand,
1959)
2-3cm/200-1000a,1cm/240a (Bennett,1955)
1cm/100a (Kukal,1964)
? Soil loss rate
Normal erosion,0.1-0.6 t/acre a (0.25-1.48t/ha a,25-128t/km2 a)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 9 of 56
(2) Classification of soil erosion
Permissible/tolerance erosion
1.24-14.84t/ha a (Smith and Stamey,1965)
6.75 t/ha a (Kohnke and Bertrand,1959)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 10 of 56
(2) Classification of soil erosion
By erosion development
? Depending on different erosion form
? Sheet
? Gully
? Intrasoil wash
? Tunnel
? Darst
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 11 of 56
(2) Classification of soil erosion
? Classification of eroded soil
on arable land,on pastures,forest soil,by wind
erosion
? Classification of erosion remains
relics,rudiments,selective remains,inhibited
remains
? Classification of sediments
according to,erosion factors,buried soil
? Classification of eroded land
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 12 of 56
(3) Climate and soil erosion
Climate applications
? Ptolemy,climate zone
? Ecological work,
Climate and plant distribution (Von Humboldt,
1799)
Climate and soil genesis and distribution
(Dokutschajeff,1879)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 13 of 56
(3) Climate and soil erosion
Climate applications
? Geomorphologic work,land form,
physiographc processes
? Soil erosion,related to all these factors-
Climate,wind velocity,rainfall intensity,
temperature,etc,
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 14 of 56
(3) Climate and soil erosion
Soil erosion causing factors
? Climate
? Climate complex
? Individual climate factors
? Soil
? vegetation
? landform
? Soil conservation practices
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 15 of 56
(3) Climate and soil erosion
Individual climate factors--Precipitation
? Individual storm
? Average quantities
? Example
100mm/month
one 5-hour storm
ten 10mm/event storms
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 16 of 56
(3) Climate and soil erosion
variables
? Intensity
? Duration
? Amount,determined by intensity and
duration
? Types,storms event,seasonal distribution
? Time-area-intensity relationships
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 17 of 56
(3) Climate and soil erosion
Individual climate factors
? Wind
Velocity/Soil protection
Potentially an agent of erosion in all climates
not only arid semi-arid climates
? Temperature
Weathering processes
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 18 of 56
(3) Climate and soil erosion
Climate complex– climate and normal erosion
? Wet and humid regions– protected by forest
? Subhumid lands– protected by tall prairie grasses
? Semiarid areas-- protected by short grasses
? Deserts-- protected by desert shrubs partially
? Regards to erosion–
Greatest natural weakness lies on the drier margins
of semiarid climate and within arid regions
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 19 of 56
(3) Climate and soil erosion
Climate complex– climate and accelerated
erosion
? Since baring the soil allows the climatic elements
to operate to their fullest capacity,climate
becomes extremely important in considering
accelerated erosion,
? Where rainfall intensities are highest and
rainstorm durations are at a maximum,gullying
and sheet washing cause the greatest damage,
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 20 of 56
(3) Climate and soil erosion
Climate complex– climate and accelerated
erosion
? Wet and humid regions–
Potentially at maximum rate where the land
has been bared
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 21 of 56
(4) Soil erosion models
? Classification
Empirical models
Dynamic/process-based models
? Purpose
Simulating soil loss and sediments
Evaluating soil and water conservation
practices
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 22 of 56
Empirical soil erosion models
? Larger time scale,
month
half-month
? Statistical relationships
? Soil loss from slope field
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 23 of 56
An example for
empirical soil erosion models
Multiply method
? USLE,Universal Soil Loss Equation
RUSLE,Revised Universal Soil Loss
Equation
? CSLE,Chinese Soil Loss Equation
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 24 of 56
USLE/CSLE
A=RKLSCP
? Rainfall erosivity factor（ R）
? Soil erodibility factor（ K）
? Slope length and gradient factor（ LS）
? Crop and management factor（ C）
? Practice factor for soil conservation (P)
? In CSLE,CP=BET
? BET,Biological,engineering,tillage practices
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 25 of 56
Process-based soil erosion models
? Smaller time scale,daily/hourly
? Processes of soil erosion
? Statistical relationships for some
parameters and processes based on
experiments
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 26 of 56
Process-based soil erosion models
WEPP (USA)
water erosion prediction project
EROSUM (EU)
European Soil Erosion Model
LISEM (Netherlands)
Limburg Soil Erosion Model
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 27 of 56
(5) Erosion and productivity
? Soil loss estimation
Weight of soil loss W in t/ha a
Depth of soil loss d in mm/a,
d=W(weight)/B (soil bulk density)
B,bulk density in t/ha mm
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 28 of 56
(5) Erosion and productivity
? Productivity losses
减产率, y=f(d)(%)
土层厚度修正, (d/Da)*100%
土壤寿命估算, Da/d
d,annual soil loss in mm/a
Da,total soil depth in mm
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 29 of 56
(6) Rainfall factor for soil erosion model
? Rainfall erosivity for USLE
? Estimation of rainfall erosivity
? Rainfall erosivity for CSLE
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 30 of 56
Rainfall erosivity for USLE
R=EI30
? R-- EI parameter for one storm,in MJ
mm/h ha
? E-- total storm energy,in MJ/ha
? I30-- the maximum 30-min intensity,in
mm/h
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 31 of 56
Rainfall erosivity for USLE
Rave=(1/N)?? (? (EI30))
? Rave-- average annual erosivity,in MJ
mm/h ha a
? N-- number of years
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 32 of 56
Rainfall erosivity for USLE
E=?(e*p)
? e-- kinetic energy in unit rainfall,in
MJ/ha mm
? p-- breakpoint rainfall amount,in mm
e=0.119+0.0873log10(i) i<=76mm/h
e=0.283 i >76mm/h
? i-- breakpoint rainfall intensity,in mm/h
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 33 of 56
Estimation of rainfall erosivity
R- average annual erosivity (MJ·mm/(ha·h·a)
P- the 2-yr frequency,6-h rainfall amoutn(mm)（ Wischmeier 1974）
Arnoldus,R- annual erosivity(t?m?cm?ha-1?h-1?yr-1)
pi- average monthly rainfall（ mm）
P- average annual rainfall（ mm）
F-modified Fournier index
17.20 0 4 2.0 PR ?
PpF
i
i /)(
12
1
2?
?
?
50.12 6 4.0 FR ?
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 34 of 56
Estimation of rainfall erosivity
Yu(Australia),
R-erosivity(MJ?mm?ha-1?h-1?yr-1)
P- annual precipitation(mm)
F- modified Fournier index
61.10438.0 PR ? 41.182.3 FR ?
or
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 35 of 56
Estimation of rainfall erosivity
Renard(USA),
R- annual erosivity(MJ?mm?ha-1?h-1?yr-1)
P- average annual rainfall（ mm）
F- modified Fournier index
6 1 0.10 4 8 3 0.0 PR ?
20 0 4 1 0 5.02 1 9.18.5 8 7 PPR ???
8 4 7.17397.0 FR ?
24 7 7 0.00 8 1.677.95 FFR ???
P<850mm
P>850mm
F<55mm
F>850mm
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 36 of 56
Estimation of rainfall erosivity
Mikhailova
R- annual erosivity（ MJ?mm?ha-1?h-1?yr-1）
P- average annual rainfall (mm)
E- elevation（ m）
EPR 7 1 9 0.20 0 0 1.73.6 9 9－ ???
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 37 of 56
Estimation of rainfall erosivity
Richardson,
Ri- half-month erosivity for the ith half-
month(MJ?mm?ha-1?h-1?yr-1)
k- days for the ith half-month
Di- rainfall for the jth day in the ith half-month
（ mm）
?
??
?
?
k
1j
DiRi
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 38 of 56
Estimation of rainfall erosivity
黄炎和等,
R- annual erosivity（ J?cm?m-2?h-2?y-2）
Pi≥ 20- monthly rainfall only larger than 20mm
（ mm）
? ?? 12 5 6 8 2.1200199.0i iPR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 39 of 56
Estimation of rainfall erosivity
吴素业,
R- annual rainfall（ J?cm?m-2?h-2?y-2）
Pi- monthly rainfall（ mm）
?? 12 6295.10 1 2 5.0
i
iPR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 40 of 56
Estimation of rainfall erosivity
周伏建等,
R- annual erosivity（ J?cm?m-2?h-2?y-2）
Pi- monthly rainfall（ mm）
?
?
??? 12
1
3046.06398.2
i
iPR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 41 of 56
Estimation of rainfall erosivity
马志尊,
R- annual rainfall（美制单位）
P- annual rainfall（ mm）
Pi - monthly rainfall （ mm）
?
?
?? 12
1
8188.0)(5.1 2102157.1
i
L o g pipR
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 42 of 56
Rainfall erosivity for CSLE
? A threshold for erosive rainfall
? Rainfall erosivity estimation
? Seasonal distribution of rainfall erosivity
? Isoerodent map for China
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 43 of 56
Research problems
? A threshold for erosive rainfall
different
but no reason and evaluation
? Rainfall erosivity index,EI30
data limited
complicated calculation
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 44 of 56
Research problems
? Seasonal distribution of rainfall erosivity
much data should be used for climate diversity
? Isoerodent map for China
much data should be used for complicated
environment
simplifying calculations
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 45 of 56
A threshold for erosive rainfall
Method
? More than 300 events during 1961-1969
? Erosive rainfall erosivity = non-erosive
erosivity
? Assessment index,3
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 46 of 56
A threshold for erosive rainfall
Results
? Rainfall amount,12mm
? Average rainfall intensity,0.04mm/min
? Peak rainfall intensity for 30-min,0.25mm/min
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 47 of 56
Rainfall erosivity estimation
? EI30－ Rainfall process data with break
point intensity
? PI10－ Rainfall event data with amount and
peak intensity for 10-min
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 48 of 56
Rainfall erosivity estimation
? 12 plots 214 plot-year data,PI10
? 14 weather station 1142 rainfall event data,
EI30＝ 0.1773（ PI10） R2 ＝ 0.902
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 49 of 56
Rainfall erosivity estimation
Scatter between PI10 and EI30 Index
0
500
1000
1500
2000
2500
3000
3500
4000
0 5000 10000 15000 20000
PI
10
(mm.mm.h
-1
)
EI
30
(MJ
·
mm
·
ha
-1
·
h
-1
)
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 50 of 56
Seasonal distribution of rainfall erosivity
Methods
? 104 station-year data for both daily and
event data
Rhalf-mon=0.184 ?PdI10d
? 70 station daily data for classifying seasonal
distribution of rainfall erosivity
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 51 of 56
Seasonal distribution of rainfall erosivity
Results
? 19 groups for China
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 52 of 56
Isoerodent map for China
? USA,1965,EI30
1978,EI30, 27.37P2.17
1997,EI30, 1.0667（ EI） 15
? China,?PdI10d,70 stations
a?Pdb,661 stations
a?Fmb,about 1200 stations
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 53 of 56
Distribution of soil erosion experiment stations and
weather stations
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''
) Daily rainf all
Rain fal l p rocess
Rain fal l in ten sit y
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 54 of 56
Isoerodent map for China
--using daily rainfall data of 616 stations
1
0
0
0
1 0 0
0 0
8
0
0
0
500
2
0
0
0
南昌
郑州
兰州
西安
太原
南京
南宁
长沙
武汉
贵阳
重庆
成都
6
0
0
0
100
130120
250
哈尔滨
呼和浩特
沈阳
1 0
0 0
0
银川
4
0
0
0
2
0
0
0
6
0
0
0
6 0 0
0
8 0 0
0
500
1 0 0
0 0
1
5
0
0
0
2
0
0
0
4
0
0
0
6 0 0
0
昆明
拉萨
乌鲁木齐
西宁
500
4
0
0
02
0
0
0
500
1
0
0
0
100
100
100
500
4
0
0
0
100
100
100
250
1
0
0
0
40
50
海口1
0
0
0
08
0
0
0
250
100
110
1
5
0
0
0
1009080
30
20
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 55 of 56
Isoerodent map for China
--using annual rainfall data of 2180 stations
15
0 00
海口
15
0 00
2000
20
0
0
10
0
00
1000
6000
8000
20
0
0
250
500
60
0 0
10
0
0
40
0
0
哈尔滨
沈阳
南昌
南京
武汉
西安
太原
郑州
呼和浩特
南宁
成都
重庆
长沙
130110 120
80 90 100
20
0
0
500
10
0
00
60
0
0
80
0
0
40
0
0
拉萨
100
250
50
10 0 0
昆明
80 0 0
兰州
银川
西宁
100
6000
4000
100
250
250
20
0
0
1000
2000
乌鲁木齐
250
250
500
10
0
0
500
500
250
30
100
40
250
250
80 0 0
10
0
00
20
Chapter 5
2012-3-21 Assessment of Climate/Change Impacts 56 of 56
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