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Jianhua Xu

East China Normal University, The Research Centre for East-West Cooperation in China, Faculty Member

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Jianhua Xu now is a Professor in Geography and the Director of Research Center for East-West Cooperation in China, East China Normal University.
His research interest includes Geocomputation and Geographical Modelling, especially in the field of Physical Geography and Ecological Economics. He has finished more than 30 research projects from National Natural Science Fund of China, National Social Science Fund of China, as well as provinces and ministries of China.
He has published 16 books, such as Geographical Systems Analysis, Systems Analysis of Agro-ecological Economic, Human ecological system, The Regional Development Theories and Research Methods, The Strategic Option for Dispelling Poverty, Mathematical Methods in Contemporary Geography (1st, 2nd and 3rd editions), Geographical Modelling Methods, Geographical Modelling Tutorial, Quantitative Geography (1st and 2nd editions), etc.
Furthermore‚ he also has published more than 200 papers in academic journals such as Hydrology and Earth System Sciences, Climate Dynamics, International Journal of climatology, Hydrological Processes, Water Resources Management, Stochastic Environmental Research and Risk Assessment, Theoretical and Applied Climatology, Advances in Meteorology, Atmosphere, Atmospheric Pollution Research, Ecohydrology, International Journal of Remote Sensing, Remote Sensing, International Journal of Applied Earth Observation and Geoinformation, Environmental Earth Sciences, Earth Science Informatics, Environmental Management, Tourism Geographies, Landscape and Urban Planning, Geographic information sciences, Chinese Science Bulletin, Chinese Geographical Science, Regional Development Studies, International Journal of Sediment Research, Journal of Geographical Sciences, International Journal of Water, Frontiers of Earth Science, The Scientific World Journal, Acta Ecologica Sinica‚ Journal of Soil and Water Conservation‚ Acta Geographica Sinica‚ Geographical Research‚ Scientia Geographica Sinica‚ Journal of Desert Research‚ Arid Land Geography‚ and Journal of Natural Disasters.
Additionally, he has worked as the editor of several academic journals, such as Journal of Desert Research, Areal Research and Development, Human Geography, Ecologic Science, Arid Land Geography, Chinese Geographical Science, Journal of Signal and Information Processing, and PeerJ, etc.
The research fields of PhD candidates supervised by professor Jianhua Xu are as follows: (1) Geo-computation; (2) ecological economy modeling.
Phone: 86-21-54341187
Address: Estuary Building, 500# Dongchuan Road, Minhang, Shanghai 200241, China.

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KU Leuven

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Università di Bologna

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UNL - New University of Lisbon

Swansea University

The University of Newcastle

Università degli Studi "La Sapienza" di Roma

National Water Research center

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Books by Jianhua Xu

Mathematical Methods in Contemporary Geography (Third edition)

Quantitative Geography (2nd edition)

Agricultural Ecologic Economic Systems Analysis

Geographical Systems Analysis

Human ecological system

The Local Geography of Gansu Province

The Regional Development Theories and Research Methods

The Strategic Option for Dispelling Poverty

Mathematical Methods in Contemporary Geography (First edition)

The Disadvantages and Advantages of Later Comer and Innovative Countermeasures for the Development of Western China

Mathematical Methods in Contemporary Geography (Second edition)

Quantitative Geography (First edition)

Geographical modelling methods

Development and application of spatial decision support system based on ecological carrying capacity

Papers by Jianhua Xu

Statistical analysis of groundwater chemistry of the Tarim River lower reaches, Northwest China

ABSTRACT This study applied a comprehensive quantitative approach including statistical, principa... more ABSTRACT This study applied a comprehensive quantitative approach including statistical, principal component and gray relation analyses to assess the groundwater chemistry based on monitored data from 840 samples collected from the lower reaches of Tarim River from 2000 to 2009. The main findings were: (1) there were six types of groundwater chemistry in the lower reaches of Tarim River where Cl center dot SO4-Na center dot Mg was the dominant type accounting for 73.57% in all samples. There were linear relationships among chemical parameters, where TDS had significant multiple correlations with Na+, K+, Mg2+, Ca2+ and Cl-, respectively. (2) Three principal components (PC1, PC2 and PC3) were extracted. They included comprehensive measurements for salinization, alkalinity and pH, respectively. Most parameters showed decreasing trends during the period of 2000-2009, as well as the scores on PC1, because the concentrations of various chemical substances were diluted due to the uplift of the groundwater table in the lower reaches and the implementation of the ecological water delivery project in 2000. (3) HCO3 (-) was the most sensitive chemical parameter affected by the groundwater table followed by TA, Mg2+, TH, SO (4) (2-) , K+, TDS and TS. PC2 was the most sensitive principal component to the change of the groundwater table followed by PC1 and PC3.

An Integrative Approach to Understand the Climatic-Hydrological Process: A Case Study of Yarkand River, Northwest China

Taking the Yarkand River as an example, this paper conducted an integrative approach combining th... more Taking the Yarkand River as an example, this paper conducted an integrative approach combining the Durbin-Watson statistic test (DWST), multiple linear regression (MLR), wavelet analysis (WA), coefficient of determination (CD), and Akaike information criterion (AIC) to analyze the climatic-hydrological process of inland river, Northwest China from a multitime scale perspective. The main findings are as follows. (1) The hydrologic and climatic variables, that is, annual runoff (AR), annual average temperature, (AAT) and annual precipitation (AP), are stochastic and, no significant autocorrelation. (2) The variation patterns of runoff, temperature, and precipitation were scale dependent in time. AR, AAT, and AP basically present linear trends at 16-year and 32-year scales, but they show nonlinear fluctuations at 2-year and 4-year scales. (3) The relationship between AR with AAT and AP was simulated by the multiple linear regression equation (MLRE) based on wavelet analysis at each time scale. But the simulated effect at a larger time scale is better than that at a smaller time scale.

Air Temperature Change in the Southern Tarim River Basin, China, 1964–2011 11-2013

The Scientific World Journal, 2013

The temperature data from 3 meteorological stations (Kashi, Ruoqiang, and Hotan) in the South of ... more The temperature data from 3 meteorological stations (Kashi, Ruoqiang, and Hotan) in the South of Tarim River Basin (STRB) during 1964-2011 were analyzed by Mann-Kendall test and correlation analysis. The results from Mann-Kendall test show that the surface temperature (ST), 850 hPa temperature (T850), and 700 hPa temperature (T700) exhibited upward trends, while 300 hPa temperature (T300) revealed a downward trend. On the whole, the change rate of ST, T850, T700, and T300 was 0.26∼0.46 ∘ C/10a, 0.15∼0.40 ∘ C/10a, 0.03∼0.10 ∘ C/10a, and −0.38∼−0.13 ∘ C/10a, respectively. For the periods, ST and T850 declined during 1964-1997 and then rose during 1998-2011. T700 declined during 1964-2005 and then rose during 2006-2011, while T300 rose from 1964 to 1970s and then declined. The results from correlation analysis show that T850 and T700 positively correlated with ST (< 0.01) at the all three stations and there was a negative correlation between T300 and ST at Hotan (< 0.1), while the correlation is not significant at Kashi and Ruoqiang. The results indicate that there were gradient differences in the response of upper-air temperature (UT) to ST change.

Recent Response of Vegetation Water Use Efficiency to Climate Change in Central Asia

Remote Sensing

Quantifying the coupled cycles of carbon and water is essential for exploring the response mechan... more Quantifying the coupled cycles of carbon and water is essential for exploring the response mechanisms of arid zone terrestrial ecosystems and for formulating a sustainable and practical solution to issues caused by climate change. Water use efficiency (WUE), one of the comprehensive indicators for assessing plant growth suitability, can accurately reflect vegetation’s dynamic response to changing climate patterns. This study assesses the spatio-temporal changes in WUE (ecosystem water use efficiency, soil water use efficiency, and precipitation water use efficiency) from 2000 to 2018 and quantifies their relationship with meteorological elements (precipitation, temperature, drought) and the vegetation index (NDVI). The study finds that the sensitivity of NDVI to WUE is highly consistent with the spatial law of precipitation. The εPre threshold range of different types of WUE is about 200 mm or 1600 mm (low-value valley point) and 300 mm or 1500 mm (high-value peak point), and the εT...

Spatiotemporal Response of Hydrological Drought to Meteorological Drought on Multi-Time Scales Concerning Endorheic Basin

International Journal of Environmental Research and Public Health

Under the controversial background of “Northwestern China is gradually developing towards warm an... more Under the controversial background of “Northwestern China is gradually developing towards warm and humid”, how hydrological drought responds to meteorological drought at the endorheic basin is of great significance. To address this problem, we first analyzed the spatiotemporal variation of meteorological and hydrological droughts at Tarim Basin River from 1960 to 2014 by using the daily standardized precipitation index (SPI) and daily standardized terrestrial water storage index (SWSI) based on the reanalysis data. Thereafter, we explored the spatiotemporal response of hydrological drought to meteorological drought on the multi-time scale by using the cross-wavelet transform method, Ensemble Empirical Mode Decomposition (EEMD), and correlation analysis. We find that: (1) both meteorological and hydrological droughts signified a gradually weakened trend in time; (2) meteorological and hydrological drought have significant resonance periods on the 10-month time scale and the 8-year ti...

Complex network analysis of climate change in the Tarim River Basin, Northwest China

Sciences in Cold and Arid Regions, 2018

The complex network theory provides an approach for understanding the complexity of climate chang... more The complex network theory provides an approach for understanding the complexity of climate change from a new perspective. In this study, we used the coarse graining process to convert the data series of daily mean temperature and daily precipitation from 1961 to 2011 into symbol sequences consisting of five characteristic symbols ( i.e. , R , r , e , d and D ), and created the temperature fluctuation network (TFN) and precipitation fluctuation network (PFN) to discover the complex network characteristics of climate change in the Tarim River Basin of Northwest China. The results show that TFN and PEN both present characteristics of scale-free network and small-world network with short average path length and high clustering coefficient. The nodes with high degree in TFN are RRR , dRR and ReR while the nodes with high degree in PFN are rre , rrr , eee and err , which indicates that climate change modes represented by these nodes have large probability of occurrence. Symbol R and r ar...

Mathematical Methods in Contemporary Geography (Third edition)

Quantitative Geography (2nd edition)

Agricultural Ecologic Economic Systems Analysis

Geographical Systems Analysis

Human ecological system

The Local Geography of Gansu Province

The Regional Development Theories and Research Methods

The Strategic Option for Dispelling Poverty

Mathematical Methods in Contemporary Geography (First edition)

The Disadvantages and Advantages of Later Comer and Innovative Countermeasures for the Development of Western China

Mathematical Methods in Contemporary Geography (Second edition)

Quantitative Geography (First edition)

Geographical modelling methods

Development and application of spatial decision support system based on ecological carrying capacity

Statistical analysis of groundwater chemistry of the Tarim River lower reaches, Northwest China

ABSTRACT This study applied a comprehensive quantitative approach including statistical, principa... more ABSTRACT This study applied a comprehensive quantitative approach including statistical, principal component and gray relation analyses to assess the groundwater chemistry based on monitored data from 840 samples collected from the lower reaches of Tarim River from 2000 to 2009. The main findings were: (1) there were six types of groundwater chemistry in the lower reaches of Tarim River where Cl center dot SO4-Na center dot Mg was the dominant type accounting for 73.57% in all samples. There were linear relationships among chemical parameters, where TDS had significant multiple correlations with Na+, K+, Mg2+, Ca2+ and Cl-, respectively. (2) Three principal components (PC1, PC2 and PC3) were extracted. They included comprehensive measurements for salinization, alkalinity and pH, respectively. Most parameters showed decreasing trends during the period of 2000-2009, as well as the scores on PC1, because the concentrations of various chemical substances were diluted due to the uplift of the groundwater table in the lower reaches and the implementation of the ecological water delivery project in 2000. (3) HCO3 (-) was the most sensitive chemical parameter affected by the groundwater table followed by TA, Mg2+, TH, SO (4) (2-) , K+, TDS and TS. PC2 was the most sensitive principal component to the change of the groundwater table followed by PC1 and PC3.

An Integrative Approach to Understand the Climatic-Hydrological Process: A Case Study of Yarkand River, Northwest China

Taking the Yarkand River as an example, this paper conducted an integrative approach combining th... more Taking the Yarkand River as an example, this paper conducted an integrative approach combining the Durbin-Watson statistic test (DWST), multiple linear regression (MLR), wavelet analysis (WA), coefficient of determination (CD), and Akaike information criterion (AIC) to analyze the climatic-hydrological process of inland river, Northwest China from a multitime scale perspective. The main findings are as follows. (1) The hydrologic and climatic variables, that is, annual runoff (AR), annual average temperature, (AAT) and annual precipitation (AP), are stochastic and, no significant autocorrelation. (2) The variation patterns of runoff, temperature, and precipitation were scale dependent in time. AR, AAT, and AP basically present linear trends at 16-year and 32-year scales, but they show nonlinear fluctuations at 2-year and 4-year scales. (3) The relationship between AR with AAT and AP was simulated by the multiple linear regression equation (MLRE) based on wavelet analysis at each time scale. But the simulated effect at a larger time scale is better than that at a smaller time scale.

Air Temperature Change in the Southern Tarim River Basin, China, 1964–2011 11-2013

The Scientific World Journal, 2013

The temperature data from 3 meteorological stations (Kashi, Ruoqiang, and Hotan) in the South of ... more The temperature data from 3 meteorological stations (Kashi, Ruoqiang, and Hotan) in the South of Tarim River Basin (STRB) during 1964-2011 were analyzed by Mann-Kendall test and correlation analysis. The results from Mann-Kendall test show that the surface temperature (ST), 850 hPa temperature (T850), and 700 hPa temperature (T700) exhibited upward trends, while 300 hPa temperature (T300) revealed a downward trend. On the whole, the change rate of ST, T850, T700, and T300 was 0.26∼0.46 ∘ C/10a, 0.15∼0.40 ∘ C/10a, 0.03∼0.10 ∘ C/10a, and −0.38∼−0.13 ∘ C/10a, respectively. For the periods, ST and T850 declined during 1964-1997 and then rose during 1998-2011. T700 declined during 1964-2005 and then rose during 2006-2011, while T300 rose from 1964 to 1970s and then declined. The results from correlation analysis show that T850 and T700 positively correlated with ST (< 0.01) at the all three stations and there was a negative correlation between T300 and ST at Hotan (< 0.1), while the correlation is not significant at Kashi and Ruoqiang. The results indicate that there were gradient differences in the response of upper-air temperature (UT) to ST change.

Recent Response of Vegetation Water Use Efficiency to Climate Change in Central Asia

Remote Sensing

Quantifying the coupled cycles of carbon and water is essential for exploring the response mechan... more Quantifying the coupled cycles of carbon and water is essential for exploring the response mechanisms of arid zone terrestrial ecosystems and for formulating a sustainable and practical solution to issues caused by climate change. Water use efficiency (WUE), one of the comprehensive indicators for assessing plant growth suitability, can accurately reflect vegetation’s dynamic response to changing climate patterns. This study assesses the spatio-temporal changes in WUE (ecosystem water use efficiency, soil water use efficiency, and precipitation water use efficiency) from 2000 to 2018 and quantifies their relationship with meteorological elements (precipitation, temperature, drought) and the vegetation index (NDVI). The study finds that the sensitivity of NDVI to WUE is highly consistent with the spatial law of precipitation. The εPre threshold range of different types of WUE is about 200 mm or 1600 mm (low-value valley point) and 300 mm or 1500 mm (high-value peak point), and the εT...

Spatiotemporal Response of Hydrological Drought to Meteorological Drought on Multi-Time Scales Concerning Endorheic Basin

International Journal of Environmental Research and Public Health

Under the controversial background of “Northwestern China is gradually developing towards warm an... more Under the controversial background of “Northwestern China is gradually developing towards warm and humid”, how hydrological drought responds to meteorological drought at the endorheic basin is of great significance. To address this problem, we first analyzed the spatiotemporal variation of meteorological and hydrological droughts at Tarim Basin River from 1960 to 2014 by using the daily standardized precipitation index (SPI) and daily standardized terrestrial water storage index (SWSI) based on the reanalysis data. Thereafter, we explored the spatiotemporal response of hydrological drought to meteorological drought on the multi-time scale by using the cross-wavelet transform method, Ensemble Empirical Mode Decomposition (EEMD), and correlation analysis. We find that: (1) both meteorological and hydrological droughts signified a gradually weakened trend in time; (2) meteorological and hydrological drought have significant resonance periods on the 10-month time scale and the 8-year ti...

Complex network analysis of climate change in the Tarim River Basin, Northwest China

Sciences in Cold and Arid Regions, 2018

The complex network theory provides an approach for understanding the complexity of climate chang... more The complex network theory provides an approach for understanding the complexity of climate change from a new perspective. In this study, we used the coarse graining process to convert the data series of daily mean temperature and daily precipitation from 1961 to 2011 into symbol sequences consisting of five characteristic symbols ( i.e. , R , r , e , d and D ), and created the temperature fluctuation network (TFN) and precipitation fluctuation network (PFN) to discover the complex network characteristics of climate change in the Tarim River Basin of Northwest China. The results show that TFN and PEN both present characteristics of scale-free network and small-world network with short average path length and high clustering coefficient. The nodes with high degree in TFN are RRR , dRR and ReR while the nodes with high degree in PFN are rre , rrr , eee and err , which indicates that climate change modes represented by these nodes have large probability of occurrence. Symbol R and r ar...

A Comprehensive Approach to Assess the Hydrological Drought of Inland River Basin in Northwest China

Atmosphere, 2018

How to measure and quantitatively assess hydrological drought (HD) in the inland river basins of ... more How to measure and quantitatively assess hydrological drought (HD) in the inland river basins of Northwest China is a difficult problem because of the complicated geographical environment and climatic processes. To address this problem, we conducted a comprehensive approach and selected the Aksu River Basin (ARB) as a typical inland river basin to quantitatively assess the hydrological drought based on the observed data and reanalysis data during the period of 1980–2010. We used two mutual complementing indicators, i.e., the standardized runoff index (SRI) and standardized terrestrial water storage index (SWSI), to quantitatively measure the spatio-temporal pattern of HD, where the SRI calculated from the observed runoff data indicate the time trend of HD of the whole basin, while SWSI extracted from the reanalysis data indicate the spatial pattern of HD. We also used the auto-regressive distribution lag model (ARDL) to show the autocorrelation of HD and its dependence on precipitat...

Modeling nitrogen and phosphorus export with InVEST model in Bosten Lake basin of Northwest China

PLOS ONE, 2019

Bosten Lake is an important region of Northwest China that has transformed from a freshwater lake... more Bosten Lake is an important region of Northwest China that has transformed from a freshwater lake to a saltwater lake since the 1970s. The water quality in the Bosten Lake basin is important for social and economic development, and nitrogen (N) and phosphorus (P) are the key indicators of water quality. The land use data, precipitation data and Digital Elevation Model (DEM) data with the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model were used to simulate the N and P exports of the Bosten Lake basin. The spatial and temporal dynamics of nitrogen and phosphorus exports, and the response of nitrogen and phosphorus exports to land use change and precipitation change were analyzed between 2000 and 2015. The results show that the amount of N and P exports increased during 2000-2015, and the N and P exports are mainly distributed around Bosten Lake. The N and P exports are greatly affected by cultivated land, built-up areas and grassland, while they are less affected by other land use types. The high precipitation areas with small exports of N and P are mainly distributed in mountain areas, while small precipitation areas with large exports of N and P are distributed in plains where the cultivated land and built-up areas are concentrated. The InVEST model can be used in Northwest China, and the statistical downscaling of reanalysis precipitation data can be used in the InVEST model to improve the simulation accuracy in the data scarce regions of Northwest China.

An approach to simulate the climate-driven streamflow in the data-scarce mountain basins of Northwest China

Journal of Earth System Science, 2019

With global warming, the inland river basin in the arid region of Northwest China is facing a ser... more With global warming, the inland river basin in the arid region of Northwest China is facing a serious water supply situation. The headwater basin of the inland river is located in the high-altitude mountainous region, and there are few meteorological observation sites, so it is difficult to apply distributed hydrological models and other models based on the physical mechanism of runoff generation to evaluate climate change and its impact on streamflow. To simulate the climate-driven streamflow in datascarce mountain basins of Northwest China, we developed an integrated approach by using downscaled reanalysis data, Mann-Kendall test, ensemble empirical mode decomposition and backpropagation artificial neural networks together with the weights connection method. We validated the approach in the Kaidu River basin located in the Tianshan mountains. The results showed that the streamflow increased 12.9% by 2.5 × 10 8 m 3 per decade with the warm and wet climate, while the average annual temperature increased 5.2% at a rate of 0.3 • C per decade and the precipitation increased 37.3% at a rate of 16.4 mm per decade during the period from 1980 to 2015. The impact of temperature variability on streamflow was 44.21 ± 2.08% and the impact of precipitation variability on streamflow was 55.79 ± 2.08%.

Modeling the multiple time scale response of hydrological drought to climate change in the data-scarce inland river basin of Northwest China

Arabian Journal of Geosciences, 2019

It is difficult to quantitatively assess the response of hydrological drought (HD) to climate cha... more It is difficult to quantitatively assess the response of hydrological drought (HD) to climate change in the inland river basins of northwest China because of the complicated geographical environment and scarce data. To address this problem, we conducted a hybrid model by integrating the ensemble empirical mode decomposition (EEMD), the long short-term memory (LSTM) model, and the statistical downscaling method and selected the Aksu River Basin (ARB) as a typical representative of data-scarce inland river basin in northwest China to simulate its hydrological drought in the period of 1980-2015 based on reanalysis climate data and hydrological observation data. The coefficient of determination (R 2), the mean absolute error (MAE), the Nash-Sutcliffe efficiency coefficient (NSE), and the index of agreement d (d index) all showed high simulation accuracy of the hybrid model (R 2 = 0.712, MAE = 0.304, NSE = 0.706, and d index = 0.901 of the Aksu River Basin), and the simulated effect of the hybrid model is much better than that of a single long short-term memory model. The simulated results in the Aksu River Basin by the model revealed that hydrological drought in the two subbasins (i.e. the Kumarik River Basin (KRB) and the Toshkam River Basin (TRB)) showed similar cycles on the seasonal scale, the interannual scale, and the interdecadal scale, which are mainly controlled and influenced by regional climate change. On the seasonal scale, the effect of precipitation and temperature on hydrological drought is not significant; on the interannual scale, precipitation is the key factor compared to temperature in inducing hydrological drought change; on the interdecadal scales, the correlations between precipitation, temperature, and hydrological drought were the strongest and most significant.

A hybrid model to assess the impact of climate variability on streamflow for an ungauged mountainous basin

Climate Dynamics, 2017

climate, the streamflow respectively increased 1.5 × 10 8 and 3.3 × 10 8 m 3 per decade in the Ku... more climate, the streamflow respectively increased 1.5 × 10 8 and 3.3 × 10 8 m 3 per decade in the Kumarik River and the Toshkan River; and (3) the contribution of the temperature and precipitation to the streamflow, which were 64.01 ± 7.34, 35.99 ± 7.34 and 47.72 ± 8.10, 52.26 ± 8.10%, respectively in the Kumarik catchment and Toshkan catchment. Our study introduced a feasible hybrid model for the assessment of the impact of climate variability on streamflow, which can be used in the ungauged mountainous basin of Northwest China.

Spatio-temporal variation and influence factors of PM 2.5 concentrations in China from 1998 to 2014

Atmospheric Pollution Research, 2017

Based on the remote sensing retrieval of PM 2.5 concentration data in the long-time series, both ... more Based on the remote sensing retrieval of PM 2.5 concentration data in the long-time series, both the linear regression and grey system correlation analysis methods were employed to analyze the spatial and temporal pattern, variation trend and the main influencing factors of PM 2.5 concentration in China from 1998 to 2014. The results showed that only 16.21%e24.67% of the land area in China PM 2.5 concentrations reached the annual average criterion value of 10 mg/m 3 set by the World Health Organization (WHO) in 1998e2014; the PM 2.5 concentrations were greater than 95 mg/m 3 mainly in Xinjiang Taklimakan Desert, west of Tianjin and the central region of Hebei. PM 2.5 concentration was less than 10 mg/m 3 mainly in Tibet, western Sichuan, northeastern Yunnan, Taiwan, northern Xinjiang, northern Inner Mongolia and northwest of Heilongjiang. High PM 2.5 concentration in the northwest of China was mainly affected by sand and dust, while it was mainly caused by human activities in the eastern region. Except for Taiwan, low PM 2.5 concentration areas were mainly located in the economically backward regions. The positive indicators in highly correlation with PM 2.5 concentration include the average temperature, the proportion of primary and secondary industry to GDP, industrial consumption, the proportion of fulfilled amount of investment in real estate development to GDP, SO 2 emissions and population density. The negative indicators in highly correlation with PM 2.5 concentration include the average precipitation, the average wind velocity, the proportion of the tertiary industry to GDP, and the greening coverage rate of the built-up areas.

A hybrid model to simulate the annual runoff of the Kaidu River in northwest China

Hydrology and Earth System Sciences, 2016

Fluctuant and complicated hydrological processes can result in the uncertainty of runoff forecast... more Fluctuant and complicated hydrological processes can result in the uncertainty of runoff forecasting. Thus, it is necessary to apply the multi-method integrated modeling approaches to simulate runoff. Integrating the ensemble empirical mode decomposition (EEMD), the back-propagation artificial neural network (BPANN) and the nonlinear regression equation, we put forward a hybrid model to simulate the annual runoff (AR) of the Kaidu River in northwest China. We also validate the simulated effects by using the coefficient of determination (R 2) and the Akaike information criterion (AIC) based on the observed data from 1960 to 2012 at the Dashankou hydrological station. The average absolute and relative errors show the high simulation accuracy of the hybrid model. R 2 and AIC both illustrate that the hybrid model has a much better performance than the single BPANN. The hybrid model and integrated approach elicited by this study can be applied to simulate the annual runoff of similar rivers in northwest China.

Understanding the effects of the impervious surfaces pattern on land surface temperature in an urban area

Frontiers of Earth Science, 2014

It is well known that urban impervious surface (IS) has a warming effect on urban land surface te... more It is well known that urban impervious surface (IS) has a warming effect on urban land surface temperature (LST). However, the influence of an IS's structure, components, and spatial distribution on LST has rarely been quantitatively studied within strictly urban areas. Using ETM+ remote sensing images from the downtown area of Shanghai, China in 2010, this study characterized and quantified the influence of the IS spatial pattern on LST by selecting the percent cover of each IS cover feature and ten configuration metrics. The IS fraction was estimated by linear spectral mixture analysis (LSMA), and LST was retrieved using a mono-window algorithm. The results indicate that high fraction IS cover features account for the majority of the study area. The high fraction IS cover features are widely distributed and concentrated in groups, which is similar with that of high temperature zones. Both the percent composition and the configuration of IS cover features greatly affect the magnitude of LST, but the percent composition is a more important factor in determining LST than the configuration of those features. The significances and effects of the given configuration variables on LST vary greatly among IS cover features.

Long-range cross-correlation between urban impervious surfaces and land surface temperatures

Frontiers of Earth Science, 2015

The thermal effect of urban impervious surfaces (UIS) is a complex problem. It is thus necessary ... more The thermal effect of urban impervious surfaces (UIS) is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures (LST) using complexity science theory and methods. This paper investigates the long-range crosscorrelation between UIS and LST with detrended crosscorrelation analysis and multifractal detrended crosscorrelation analysis, utilizing data from downtown Shanghai, China. UIS estimates were obtained from linear spectral mixture analysis, and LST was retrieved through application of the mono-window algorithm, using Landsat Thematic Mapper and Enhanced Thematic Mapper Plus data for 1997-2010. These results highlight a positive long-range cross-correlation between UIS and LST across People's Square in Shanghai. LST has a long memory for a certain spatial range of UIS values, such that a large increment in UIS is likely to be followed by a large increment in LST. While the multifractal long-range crosscorrelation between UIS and LST was observed over a longer time period in the WE direction (2002-2010) than in the N-S (2007-2010), these observed correlations show a weakening during the study period as urbanization increased.

The spatial relationship analysis of regional development potential and resource and environment carrying capacity in China

Scaling and simulation on measuring regional economic disparities based on grid

The measurement of regional economic disparities is a scientific issue, closely related with scal... more The measurement of regional economic disparities is a scientific issue, closely related with scale. Based on Geographical information system (GIS) technology, selecting Lorenz curve, GINI coefficient and THEIL coefficient as the measuring index, this paper discusses the spatial scaling effect using grid method by up scaling. The main findings are as follows: With the increase of spatial grain in size, GINI coefficient and THEIL coefficient both present a decreasing tendency and the degree of downward bending of Lorenz curve is also decreasing, which all show regional economic disparities decrease. With the first 3-7 increase of spatial extent, GINI coefficient and THEIL coefficient change greatly and they are no obvious regularity. Since then, the measuring results tend to stabilization with the increase of spatial extent. On the large scale, the whole spatial rule is easy to find, but the details on the small scale are omitted. Meanwhile, on the small scale, the micro rules are easy to find, but the macro rule cannot be presented. Therefore, the suitable scale in the study of regional economic disparities can be determined by the specific research purpose and research object.

The Spatial Relationship of Tourist Distribution in Chinese Cities

Tourism Geographies, 2011

ABSTRACT This study investigates the spatial dependence and mechanisms of international and domes... more ABSTRACT This study investigates the spatial dependence and mechanisms of international and domestic tourist distributions in 299 cities in mainland China through a set of Geographical Information Systems (GIS)-based spatial statistical tools. The results show that during the period of investigation (1999–2007), there was a significant degree of neighbouring effect (i.e. positive spatial correlation) in both international and domestic tourist distributions. We have also highlighted that tourism development in a given city is dependent on the developments in neighbouring cities. Specifically, the tourist distribution shows a polarized (core – periphery) spatial pattern, which is strongly connected to the economic development level and tourism resources of the cities. Furthermore, the findings reveal tourist distribution clusters that underscore the importance of geographical focus. Overall, the results imply that policy makers are encouraged to pay attention to patterns of tourist distribution.

Self-organized criticality of climate change

Theoretical and Applied Climatology, 2013

Self-organized criticality (SOC) of three climatic factors (average daily temperature, vapor pres... more Self-organized criticality (SOC) of three climatic factors (average daily temperature, vapor pressure, and relative humidity) was studied by analyzing climate records from 1961 to 2011 in Yanqi County, northwest China. Firstly, we investigated the frequency-size distribution of three climatic factors and found that they were well approximated by power-law distribution, which suggested that climatic factor might be a manifestation of self-organized criticality. Furthermore, we introduced a new numerical sandpile model with decay coefficient to reveal inherent dynamic mechanism of climatic factor. Only changing the number value of decay coefficient of climatic factors, this model would give a good simulation of three climatic factors' statistical characteristics. This study showed that it was the self-organized criticality of the climate change that results in the temporal variation of climatic factors and the occurrence of large-scale climate change events triggered by SOC behavior of the minor climatic factors. So, we believed that SOC characteristics would have practical implications for climate prediction.

Grey modelling the groundwater level dynamic in the lower reaches of Tarim River affected by water delivery from upper reaches: A demonstration from Yingsu section