Evaluation on the Natural Suitability of Urban Human Settlement Environment Using Multisource Data Jieqiong Luo, Peijun Du, Alim Samat, Li Feng Key Laboratory for Satellite Mapping Technology and Applications of State Administration of Surveying, Mapping and Geoinformation of China, Nanjing University Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Nanjing University luoj�
[email protected] [email protected] Abstractacceleration
With of
the
degeneration
urbanization,
of
urban
environment human
and
settlement
environment has been in rapid change and attracted great attentions worldwide. Meanwhile the Quantitative evolution on the natural suitability of urban human settlement environment (NSUHSE) is essential for a better and powerful understanding of the urbanization process, such as the direction and pace of the urbanization. This paper uses multisource data, including DEM, meteorological data, vegetation cover data (Normal Differential Vegetation Index, NDVI), DMSP/OLS NTL data etc. to establish the
NSUHSE
model
to
quantitatively
evaluate
the
natural
suitability of urban human settlement environment in China. The results show that the NSUHSE of China decreases from southeast to northwest in general, urban area of China is concentrated in the area with moderate high NSUHSE which is an area of 415195 2 km or 60.91 % of the country's total urban area. Moreover, NSUHSE
has
significant
influence
on
urban
distribution
according to the correlation coefficient between NSUHSE and DMSP/OLS NTL data.
Keywords-Urban Human Settlement Environment; Natural Suitability; Multisource Data; China
I.
INTRODUCTION
Urban human settlement environment(UHSE) is an important site that mankind produce with the living space and the combination of the natural, human, spiritual, political, and economic environment. It is also closely associated with, and considerably dependent upon, other broader systems at regional and global levels for resource input and waste output[l]. Since the concept of "Science of Habitat Environment" was put forward by Greece scholar Doxiadis in the 1960s[2] and the concept of "sustainable development" was fIrst proposed in the well-known report "Our Common Future" in 1987 by the UN World Commission on Environment and Development (the Brundtland Commission)[3], many scholars in the fields of architecture, planning, geography, environment and others made a lot of scientific researches on urban human settlement environment[4-6]. With the development of remote sensing technology and the abundance and sharing of remote sensing data, several trends can be found in urban human settlement environment research: 1) the research contents have been widely extended from the perspective of cultural environment factors, such as public safety, social economic, education conditions and transportation[7-9] to the natural factors which is the most fundamental and essential among these factors. Therefore, it is
of great significance to focus on NSUHSE in order to improve the quality and keep the sustainable development of UHSE, however research of natural factors mainly focus on single factor, such as climate, land cover etc.[5,1O]. 2) the research data was not just statistical and surveyed data but also satellite imagery, GIS data etc. 3) Compared with the traditional ecological and geographical method used in early period, the research methods have been improved greatly and more attentions have been paid to the application of mathematical tools, such as hierarchy analysis, fuzzy evaluation and genetic algorithm, etc.[6,1 l]. In conclusion, the research in this field has been developed rapidly both in scope and method, but there are still some deficiencies in natural factor evaluation, especially the quantitative evaluation of multiple factors synthesis. Furthermore, the integrated research at national scale based on the multisource data and spatial analysis method is still scarce. In this study, the natural suitability of urban human settlement environment is evaluated by using multi-source data. Firstly each single index model of topography, climate, hydrology and land cover was built based on the 1kmx 1km grid data. And then according to the relationship between each single index and DMSP/OLS NTL data which was used to extract urban area, an integrated NSUHSE model was established. Finally NSUHSE model was used to quantitatively evaluate the characteristics and spatial pattern of NSUHSE in China. The purposes are to analyze the natural suitability of urban human settlement environment in China, and provide the basis and decision support for the urban human settlement environment sustainable development strategy. II.
DATA AND PROCESSING
Four types of data are used in this study: topographic data (DEM,2000), land use/cover data (2010-2012) and NDVI, climatic data(2012) including the month average temperature, wind speed, sunshine time, relative air humidity and precipitation, and other auxiliary data such as DMSP/OLS NTL data (2012), administrative division map(20 12) etc.. SRTM3 DEM at 90m is provided by International Scientific & Technical Data Mirror Site, Computer Network Information Center, Chinese Academy of Sciences (http://www.gscloud. cn). Two kinds of land cover status data were used in this research: one is 30m global land cover data that was downloaded from Global Land Cover Information Service System (http://www.globallandcover.com/GLC30Download/ index.aspx), which is used to calculate water area ratio and the
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other is MCD12Q1 data, used to calculate land cover index with MOD13A3 NDVI data, and they are obtained from the NASA Land Processes Distributed Active Archive Center (LP DAAC), USGS/Earth Resources Observation and Science (EROS) Center (https:lllpdaac.usgs.gov/data access). All of the meteorological data derived from the daily data of 19512014 provided by 824 fundamental stations are provided by China Meteorological Data Sharing Service System (http://cdc.cma.gov.cn/home.do). Administrative division map is provided by National Geomatics Center of China (http://ngcc.sbsm.gov.cn/). DMSP/OLS NTL data derived from Defense Meteorological Satellite Program's Operational Linescan System (http://www.ngdc.noaa.gov/eog/download. html).
Relief Amplitude Index(RAI) The relief amplitude is an important indicator to reflect regional terrain and can be characterized by the altitude and steep degree of a region. The calculation formula of relief amplitude index as below[13]:
Based on meteorological site data, the spatial grid of the month average temperature, wind speed, sunshine time, relative air humidity and precipitation in the study area are generated using ANUSPLIN (http://fennerschool.anu.edu.au/ research/products/anusplin-vrsn-44).Urban area of China in the year of 2012 was extracted based on a cluster-based method which was developed to estimate optimal thresholds and map urban extent from the DMSP/OLS NTL data [12]. The size of all grid data units is resampled to consistent with the NDVI data ( lkmx lkm). A Universal Transverse Mercator (UTM) projection with zone 48 North and WGS84 datum was applied to all data.
2)
III.
METHOD AND MODELING
J)
RAI=AE/JOOO+{[Max(H)-Min(H)jx[J-P(A)/Aj}/500 (1) where ALT is the regional average elevation in certain window area, Max(H) and Min(H) respectively represent the highest and lowest elevation, P(A) and A are the flat and total area of the region. Based on change point analysis (http://www.variation.com/cpaitech/changepoint.html). the window size of 15x 15 is recognized as the best computational unit, it also means that A equals 225 km2.
Human Thermal Comfort (HTC) Climate conditions are major factors influencing human thermal comfort and residential environment, which can be expressed by many indexes. Here three biometeorological indices considered to express the human thermal sensation were applied in the studied areas: The Physiological Equivalent Temperature (PET), the Temperature-Humidity index (THI), and the wind chill index (K)[14]. PET which can be computed with RayMan[15,16] was estimated using the equations of MEMI[17]. THI is calculated as a combination of air temperature and humidity, and K describes the loss of energy, per units of time and body surface that a human can tolerate, taking into account wind speed and sunshine time:
A. The Establishment of Single Index Models Many factors affect the NSUHSE, but topography, climate, water resource conditions and land cover are leading roles in the NSUHSE evaluation and they also can reflect some other factors. In this study the quantitative characteristics and spatial pattern of NSUHSE in China were analyzed from the single index model as Fig.1. I
Natural
I
THI = 58+(1.8t-26)(0.45+0.0055RH)
(2)
-(1 OV05 + 10.45 -v)(33-t)+8.55s
(3)
K=
where t is the ambient air temperature CC), RH is the ambient relative air humidity (%), v and s respectively represent the wind speed (ms-I) and the average sunshine time of everyday (h). After the calculation of PET, THI and K, HTC was obtained based on chinese characteristics and the criterion of reclassification[15] (Fig.2). Tbermo!
comfortabl e
Sensation
K(Wm"}
15.5 -450
11D(t)
63
PET(t) Relief Ampli rude Index
(RA1)
26
no
-260 70
stress
Physiological Equivalent Temperature (pE1) Temperature Humidity Index (TH1) Wind Chill Index
(K)
Water Resource Index (WR1)
Land Cver Index (L e1)
if
I
� - - ..... Level 3 \
,index I �-;
Fig. 1. An integrated NSUHSE model for evaluating natural suitability of urban human settlement environment
Fig. 2. PET, THI and K ranges for various thermal sensation and stress levels
3)
Water Resource Index (WRJ) The precipitation embodies the capacity of water supply in natural state and the water area represents the catchment capacity in a region, so the ratio of precipitation and water area was used to represent the abundance and deficiency of water resource[13]. The detailed formula is given as follows: WRJ = aP+fJWa
(4)
where P and Wa respectively represent the normalized precipitation and water area ratio. The value of a and fJ respectively were 0.24 and 0.76 according to the correlation of precipitation and water area ratio with DMSP/OLS NTL data.
Land Cover Index (LCI) Land cover is the signature imprint of human habitation on the surface of the Earth. It also denotes the human employment, physical and biotic character of the land, so it directly reflect the suitability of human settlement environment. According to the Environment Protection Industry Criterion of China[18], Its calculation formula is: 4)
LCI = LT; x NDVI
N
A
(5)
where LT; is the coefficient of various land use types, NDVI is normalized difference vegetation index. B.
The Establishment ojNSUHSE Evaluation Model
Due to each single index which comes from different source of data has different dimension, it is not comparable and difficult to make a comprehensive summary measures, so each single index should be normalized to eliminate the influence of dimensional and only through numerical to reflect the size of the parameter values. And then the NSUHSE model could be established as follows:
NSUHSE=axNRAl+{JxNHTC+yxNWRI+c5xNLCI
According to the relationship between the normalized natural environmental factors and DMSP/OLS NTL data, the weight of each single index was calculated as TABLE I. THE WEIGHT AND THE COEFFICIENT OF EVALUATION INDEX AND DMSP/OLS NTL DATA Level 2 Indices
Content Correlation with OLS NTL data
DMSPI
Weight
IV.
A.
RAI
HTC
WRI
LCI
0.407
0.179
0.387
0.270
0.327
0.144
0.312
0.217
RESULTS
The Spatial Distribution Pattern ojNSUHSE in China
Fig.3 shows that the NSUHSE in South China is higher than that of the North, and the East larger than that of the West and most areas of South and Central China have the largest NSUHSE and the lowest value of it is found in northwest of Qinghai-Tibet Plateau and the desert area between the north and the south of Tianshan Mountain. B.
0.92
0.13
o 500 1.000 _
(6)
where NRAJ, NHTC, WRI and NLCI are the normalized relief amplitude index, human thermal comfort, water resource index and land cover index, respectively. a, {J, y and c5 are the weight of each single index.
TABLE I.
NSUHSE
The Quantitative Evaluation oj the Subarea NSUHSE in China
Based on the distribution pattern and characteristics of NSUHSE, the natural breaks grading method which used a technique called Jenks Optimization to iteratively calculate best classification strategy was adopted to divide the NSUHSE into five levels, including unsuitable urban area, critical suitable urban area, low suitable urban area, moderate suitable urban area and high suitable urban area(FigA and Table II).
2.000 Kilometers
Fig. 3. Spatial distribution of NSUHSE in China, excluding Taiwan, Hongkong and Macau due to their lack of meteorological data
THE RESULT OF NSUHSE IN vARlOUS REGIONS
TABLE I!.
Region Area/km2
Suitable Type Low Moderate suitable suitable
Unsuitable
Critical Suitable
North
0
3930
69195
54212
2973
Northeast
0
681
52500
16496
2996
East
0
85
32542
139370
41089
South-central
0
120
26019
6481 I
42687
Southwest
4
1006
18309
27646
9807
31
869
174
88
9
Northwest
153
11871
49050
12245
765
Total
188
18562
247790
314869
100326
Percentage/%
0.03
2.72
36.35
46.19
14.72
Tibet
High suitable
The result shows that NSUHSE is an important factor influencing urban distribution and most urban areas in China concentrate in regions with high natural suitability. More specifically: I)The unsuitable urban area covering an area of 188 km2 or 0.03% of the country's total urban area is mainly located in Qinghai-Tibet Plateau, Junggar Basin and Tarim Basin; 2) The critical suitable urban area with a land area of 18562 km2, accounting for 2.72% of the total urban area is mainly located in the periphery of the unsuitable urban area, Inner Mongolian Plateau, Loess Plateau; 3)The low suitable urban area with an area of 247790 km2 or 36.35% of the country's total urban area is mainly located in the Plain of North China, Northeast China and Northwest China, south of the Loess Plateau, north of East China and the Yunnan Guizhou Plateau and southern Tibet; 4)The moderate suitable urban area with a land area of 314869 km2 or nearly half
(46.19%) of the total urban area is mainly situated in the periphery of the low suitable urban area, especially in the southeast of North China Plain, the central and north of East China and South-central China; 5)The high suitable urban area covering an area of lO0326 km2 or 14.72% of the total urban area is mainly located in the central and south of East China, South-central China and Southwest China. N
Acknowledgment This work was supported in part by the Jiangsu Provincial Natural Science Foundation (BK2012018). The authors would like to thank all the organizations for sharing data.
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A
_ Unsuitable urban arca � _ Critical suitable urban area D Low suitable urban area _ Moderate suitable urban area _ High suitable urban area D No climate data and no light area .
o ' ': CJ .
o 500 t ,000 2.000 ___==- ___ K.ilometers _:'
.
,_.1....-..:::...._--'
Fig. 4. Subarea classification map of NSUHSE in China, excluding Taiwan, Hongkong and Macau due to their lack of meteorological data
V.
DISCUSSION AND CONCLUSION
Multisource data were integrated to establish the NSUHSE model to quantitatively evaluate the natural suitability for urban human settlement environment in China. The results show that the NSUHSE of China decreases from southeast to northwest in general, urban area of China is concentrated in the area with moderate high NSUHSE which is an area of 415195 km2 or 60.91% of the country's total urban area. Moreover, NSUHSE has significant influence on urban distribution according to the correlation coefficient between NSUHSE and DMSP/OLS NTL data. The results presented here offer several possible avenues for future research. Based on this study a more comprehensive urban human environment suitability model can be built up through adding social, economic and educational factors. In addition, multisource data with finer spatial resolution and higher temporal resolution are becoming available, which will potentially help to establish better NSUHSE model to quantitatively evaluate its spatial-temporal dynamic change and make it possible to set up an urban human settlement basic database with mUltiple time and space scale. It is also can better provide the basis and decision support for the future urban human settlement environment sustainable development strategy.
for
Human
Settlements.
Athens: Athens
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