urban soil sealing and compaction and their eco
TRANSCRIPT
Urban soil sealing and compaction and their eco-
environmental impacts
Gan-Lin Zhang, Jin-Ling Yang, Ren-Fang Shen
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences
1984 1995 2003 2000
Urbanization (1984~2003, Nanjing)
1984～1995 1995～2000 2000～2003 2003
Initial area (ha) 334,800 568,100 694,000 843,900
Expanded area 233,300 126,000 149,900 －
Annual expansion 21,200 25,200 49,990 －
Percent of urban 3.28 5.56 6.79 8.26
Increase rate (%) 6.33 4.43 7.20 －
Urban development and land use / land cover change
TM and SPOT ,1998
SPOT ,1999
1985
1999
2020 0
100
200
300
400
500
600
1940 1950 1960 1970 1980 1990 2000 2010 2020年份
面积km2
City Expansion of Zhengzhou, China
By 2030, 60% of the world people will live in urban area In China: 10.6% in 1949 to more than 50% in 2012
0
10
20
30
40
50
60
70
80
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
年份
城市
化率
%
世界发达国家和地区发展中国家和地区中国
World
Developed country
Urb
aniz
atio
n le
vel %
Year
Developing country
China
Conceptual model of urban expansion
Zhao and Zhang, • CATENA, 2007,69:74-81
Soil sealing and compaction
Urbanization in Nanjing, China
compaction sealing
sealing compaction
Various soil sealing
Milan, Italy
NYC, USA
Berlin, Germany
Nanjing, China
Benefits of soil sealing and compaction for citizen
Landscape and amusement services of soil resource in urban area
Soil sealing and compaction on physical properties of urban soils
Soil under surface sealing
Soil compaction
Extraneous materials
Bulk density of total soil and fine earth fraction of a vegetable farm site and a
construction site0
20
40
60
80
100500 750 1000 1250 1500 1750
Depth, cm
Bul
k de
nsity
, g/c
dm
Total fractionvegetablefarm
Total fractionconstructionsite
Feine earthfractionvegetablefarmFine earthfraction constructionsite
Skeleton (stone) content of vegetable farm and constriction
site soil0
20
40
60
80
1000 20 40 60 80
Skeleton content, %
Dep
th, c
m
VegetablefarmConstruction site
Burghardt
0
50
100
150
200
1,2 1,4 1,6 1,8
Bulk density (compaction), g/cm2
Dep
th, c
m3
Low
Moderate
High
Deep soil compaction from several layers from soil deposition by scraper
3
Burghardt
Soil bulk density and porosity
0
10
20
30
40
1.1~1.2 1.2~1.3 1.3~1.4 1.4~1.5 1.4~1.6 <1.6
容重（g cm-3）
频率
（%）
城郊
城区
0
10
20
30
<40 40~42 42~44 44~46 46~48 48~50 >50总孔隙度（%）
频率（%）
城郊
城区
0
10
20
30
40
<38 38~40 40~42 42~44 44~46 46~48毛管孔隙度（%）
频率（%）
城郊
城区
0
10
20
30
40
50
<2 2~4 4~6 6~8 8~10 >10通气孔隙度（%）
频率（%）
城郊
城区
0
100200300400500600700800
0 50 100 150 200时间（min）
入渗率（
mm
h-1）
J003
J004
道路绿化带无植被新土
0
50
100
150
200
250
300
350
0 100 200 300时间（min）
入渗
率（
mm
h-1）
J023J024J030
公园无植被老土
0
150
300
450
600
750
900
0 40 80 120 160 200
时间（min）
入渗率（
mm
h-1） J002
J005J006
道路绿化带草坪新土
0
200
400
600
800
1000
1200
1400
1600
0 50 100时间（min）
入渗率（
mm
h-1） J010
J011J012
道路绿化带树下灌木老土
Soil infiltration rate under various land uses
Impacts of soil compaction on soil infiltration rate
y = -514.64x + 853.36r = 0.500**
0
200
400
600
800
1.0 1.2 1.4 1.6 1.8容重（g cm-3）
稳定
入渗
率（
mm
h-1）
y = 13.151x - 504.52r = 0.440**
0
200
400
600
800
35 40 45 50 55总孔隙度（%）
稳定入渗率（
mm
h-1）
y = 19.958x - 20.449r = 0.680***
0
200
400
600
800
0 5 10 15 20大于0.12mm实效孔径的孔度（%）
稳定入渗率（
mm
h-1）
y = 71.307x + 7.7306r = 0.509**
0
200
400
600
800
0 1 2 3 40.12~0.05mm实效孔径的孔度（%）
稳定入渗率（
mm
h-1）
y = 100.5x - 60.037r = 0.4876**
0
200
400
600
800
0.00 1.00 2.00 3.00 4.000.05~0.03mm实效孔径的孔度（%）
稳定
入渗
率（
mm
h-1）
0
200
400
600
800
0 2 4 60.03~0.01mm实效孔径的孔度（%）
稳定
入渗
率（
mm
h-1）
Ecological impacts of soil sealing and compaction
• Urban flooding • Poor water quality • Weak plant growth • Heat-island • Poor gas exchange • Lower microbial biomass and
enzyme activities
Urban flooding
Urbanization results in soil sealed surface, decreased porosity, causing losses of storage capacity of soil reservoir. The rate of loss is related to percentage of
sealed surface and compaction of greenbelt soil
Urban flooding in China
Urban flooding in Vietnam
Urbanization and climate change impacts on future urban flooding in Can Tho city, Vietnam
Huong et al., 2013
Urban land use change on regional flooding risk
• Regional flooding-mitigation capacity (RFC): total of that of all land uses
Soil capacity
Surface capacity
RFC
Water retention of the soil
• Soil has a large storage capacity for water retention – soil reservoir
• Supply water to plants for their growth
• Minimize flooding risk by holding and adjusting soil water balance
Storage capacity of soil reservoir—a case study in Nanjing, China
0
50
100
150
200
250
300
350
incompactsoil
Normal soil Lightcompaction
Moderatecompaction
Severecompaction
Stor
age
capa
city
of s
oil r
eser
voir（
mm）
Total storageFlood control storageAvailable water storageInvalid water storage
Runoff coefficient in urban soil– as a case in Nanjing, China
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
extremecompaction
Severecompaction
Moderatecompaction
Lightcompaction
Normal soil
Run
off c
oeffi
cien
t
Loss of soil reservoir due to urbanization
0
5
10
15
20
25
30
0 20 40 60 80 100 120绿地面积（%）
总库容损失（
104 m
3 km
-2）
正常土壤
轻度压实
中度压实
重度压实
Loss of capacity=normal capacity – sealed soil capacity
In Nanjing, the total green belt accounts for 40% of the total land area, if transformed from vegetable land to other (compacted) greenbelt of various compaction degrees, the loss of total soil reservoir is 14.77~16.49×104m3 km-2，while the flooding-mitigation reservoir is4.32~5.98×104m3 km-2。
0
2
4
6
8
0 20 40 60 80 100 120绿地面积（%）
滞洪库容损失（
104 m
3 km
-2）
正常土壤
轻度压实
中度压实
重度压实
A case study in the west of Nanjing, China
Land use map
±
Legend
Hexi AreawoodlandRoadRailway
0 2,000Meters
ZiJin Mountain
Yangt
se R
iver
JingHu Railway
0 2,000Meters
±林地(A)
耕地(B)
水域(C)
公园(D )
广场绿地(E )
附属绿地1(F1)
附属绿地2(F2)
附属绿地3(F3)
附属绿地4(F4)
附属绿地5(F5)
道路绿地I
封闭地表K
Sampling sites 0 2,000
Meters
±
SamplesiteBoundry
Soil compaction on soil reservoir
0 1,200Meters
4
LegendboundryWaterVery looseNormal
1986
0 1,200Meters
4
LegendboundryVery looseNormalLessModerateSevereWater
2003
0
10
20
30
40
水面 耕地 水稻 建筑 林地
面积(km2)
1986年
2003年
Wu et al., 2008
0
100
200
300
400
500
600
700
800
900
BS WL PF Al WA TOTALFlood detention capacity(104m3)
1986
2003
41.82 185.68
334.16
550.4
BS, Structure land; WL, Forest; PF, Paddy; A1, Upland; WA, Water
4000 km2 of paddy soils shifted to sealing urban area in the past 20 years, which
would cause a loss of water storage c.a. 1.0×109~1.5×109m3, a potential risk to
urban flooding events
0
100
200
300
400
500
600
700
April Mai Juni Juli Aug Sept Okto Nov Dez Jan Feb März
rainfall runoff
evapotranspiration percolation
Water (mm)
Annual water balances (Gerd Wessolek)
Mean water balance of an asphalt street, Berlin
Poor water quality
Water quality of surface runoff from urban flood
Pollutants in runoff in urban-- loads
Pollutant loads
0
1000
2000
3000
4000
May June July August
Kg/day
COD
TOC
NH4+-N
Pb
Zn
Comparison of water quality in urban area with forest and agriculture
0
2
4
6
8
NO3--N NH4+-N TN
Con
cent
ratio
n (m
g L
-1)
Urban
Forest
Agriculture
0.0
0.1
0.2
0.3
0.4
MRP TP
Con
cent
ratio
n (m
g L-1
) UrbanForestAgriculture
0
100
200
300
Suspended particles
Con
cent
ratio
n (m
g L-1
)
UrbanForestAgriculture
Yang & Zhang, 2011, JSS
Weak plant growth
Impacts of soil sealing and compaction on plants
• Soil compaction makes it difficult to establish and maintain lawns and landscaping
• Restricted root growth
• Reduced plant uptake of water and nutrients
• Reduced available water capacity
wilting-point water content vs. soil compaction
y = 20.227x - 4.9296r = 0.646***
0
5
10
15
20
25
30
35
1 1.2 1.4 1.6 1.8
容重(g cm-3)
萎蔫
点体
积含
水量
(%)
y = -0.8963x + 26.83r = 0.533***
0
5
10
15
20
25
30
35
0 3 6 9 12通气孔隙度(%)
萎蔫
点体
积含
水量
(%)
Compaction increases non-available water content
Heat-island effects
Laboratory simulations of an urban heat island in a stratified atmospheric boundary layer Falasca et al., 2013. J Vis (2013) 16:39–45
Laboratory simulation of urban heat island
Temperature of pavement surface in Beijing, China
Yang et al., 2008
lawn surface 32℃ Canopy 30 ℃
Cement surface 57 ℃ Asphalt surface 63 ℃。
Comparison of pavement surface with other land surface
Deng and Wu (2013) Remote Sensing of Environment 131: 262–274
Examining the impacts of urban biophysical compositions on surface urban heat island: A spectral unmixing and thermal mixing approach
Surface temperature in urban—a case in Berlin
An evaluation of thermal Earth observation for characterizing urban heatwave event dynamics using the urban heat island intensity metric
Holderness et al., 2013
Effects of soil sealing on air temperature—a case study in Suzhou, China
Urbanization of Suzhou (1986-1995-2006)
Diurnal variation of the mixing layer height
Diurnal variation of the inversion layer height
Effects of urban heat island on subsurface
Subsurface urban heat islands in German citiesc
Effects of urban heat island on surface and subsurface temperature—a case in Berlin
Subsurface urban heat islands in German cities
A profile from urban to suburban
Subsurface urban heat islands in German cities Menberg et al., 2013
Poor gas exchange
Model of gases migration and soil sealing
Scalenghe and Marsan, 2009 Landscape and Urban Planning
Lower microbial biomass and enzyme activities
Soil sealing and microbial biomass
Zhao et al., 2012 J Soils Sediments
Effect of soil sealing on the microbial biomass, N transformation and related enzyme activities at various depths of soils in urban area of Beijing, China
Soil sealing and enzyme activities
Zhao et al., 2012 J Soils Sediments
Urease synthesis is regulated by soil N and is repressed when the preferred N source,
protease activity was negatively correlated with SOM
Soil sealing and enzyme activities
Zhao et al., 2012 J Soils Sediments
Conclusions • Urbanization altered soil physicochemical properties. Urban soil has
high bulk density, low porosity, infiltration rate and water capacity, and high runoff coefficient
• Increased storm water runoff and flooding • Increased water pollution • Limited plant to uptake water and nutrients and extendibility of roots • partially or completely prevents the exchange of gases • affected soil microbial biomass and enzyme activities