From 1981 to 2010,the effects of climate change on evapotranspiration of the alpine ecosystem and the regional difference of effects in the Tibetan Plateau(TP)were studied based on the Lund-Potsdam-Jena dynamic vegetation model and data from 80 meteorological stations.Changes in actual evapotranspiration(AET)and water balance in TP were analyzed.Over the last 30 years,climate change in TP was characterized by sig- nificantly increased temperature,slightly increased precipitation,and decreased potential evapotranspiration(PET),which was significant before 2000.AET exhibited increasing trends in most parts of TP.The difference between precipitation and AET decreased in the south- eastern plateau and increased in the northwestern plateau.A decrease in atmospheric water demand will lead to a decreased trend in AET.However,AET in most regions increased be- cause of increased precipitation.Increased precipitation was observed in 86%of the areas with increased AET,whereas decreased precipitation was observed in 73%of the areas with decreased AET.
In this paper,variations of surface water flow and its climatic causes in China are analyzed using hydrological and meteorological observational data,as well as the impact data set(version 2.0)published by the National Climate Center in November 2009.The results indicate that surface water resources showed an increasing trend in the source region of the Yangtze River over the past 51 years,especially after 2004.The trend was very clearly shown,and there were quasi-periods of 9 years and 22 years,where the Tibetan Plateau heating field enhanced the effect,and the plateau monsoon entered a strong period.Pre- cipitation notably increased,and glacier melt water increased due to climate change,all of which are the main climatic causes for increases in water resources in the source region. Based on global climate model prediction,in the SRESA1B climate change scenarios,water resources are likely to increase in this region for the next 20 years.
The mouth bar in the Yangtze estuarine waterways has a significant influence on navigational transport within the estuary,flood discharge and construction of the Shanghai Port.In this paper the morphological evolution and mechanisms of mouth bar formation of the Yangtze estuarine waterways are studied by analyzing hundreds of years of historical data and the latest profile maps of some or the main mouth bar channels in the Yangtze Estuary. The results are shown as follows:The mouth bars in the North Branch have moved gradually from outside the mouth to the inside and formed a huge sand bar.In the North Channel,the head of the mouth bar has migrated about 30 kilometers downstream,and a channel bar has been developing since 2001.Two mouth bar tops,which always existed in the North Passage, disappeared in 2010.The head of the mouth bar in the South Passage has migrated downstream about 14 km and the number of tops increased at first but is reduced to only one now. According to the results,we can conclude that the evolution of the mouth bars differs depending on their location.In the North Branch it is directly related to large-scale reclamation in Chongming Island,but in the North Passage it has a close relationship with regulation of the Yangtze Estuary Deepwater Channel.However,the evolution of mouth bars in the North Channel and South Passage is not only connected with the Yangtze Estuary Deepwater Channel Regulation Project,but also with the reclamation in the East Hengsha Shoal and the closure of the Qingcaosha Reservoir.
The vegetation coverage dynamics and its relationship with climate factors on different spatial and temporal scales in Inner Mongolia during 2001–2010 were analyzed based on MODIS-NDVI data and climate data.The results indicated that vegetation coverage in Inner Mongolia showed obvious longitudinal zonality,increasing from west to east across the region with a change rate of 0.2/10°N.During 2001–2010,the mean vegetation coverage was 0.57,0.4 and 0.16 in forest,grassland and desert biome,respectively,exhibiting evident spatial heterogeneities.Totally,vegetation coverage had a slight increasing trend during the study period.Across Inner Mongolia,the area of which the vegetation coverage showed extremely significant and significant increase accounted for 11.25%and 29.13%of the area of whole region,respectively,while the area of which the vegetation coverage showed extremely significant and significant decrease accounted for 7.65%and 26.61%,respectively. On inter-annual time scale,precipitation was the dominant driving force of vegetation coverage for the whole region.On inter-monthly scale,the change of vegetation coverage was consistent with both the change of temperature and precipitation,implying that the vegetation growth within a year is more sensitive to the combined effects of water and heat rather than either single climate factor.The vegetation coverage in forest biome was mainly driven by temperature on both inter-annual and inter-monthly scales,while that in desert biome was mainly influenced by precipitation on both the two temporal scales.In grassland biome,the yearly vegetation coverage had a better correlation with precipitation,while the monthly vegetation coverage was influenced by both temperature and precipitation.In grassland biome,the impacts of precipitation on monthly vegetation coverage showed time-delay effects.
Knowledge of vegetation distribution patterns is very important.Their relationships with topography and climate were explored through a geographically weighted regression (GWR)framework in a subtropical mountainous and hilly region,Minjiang River Basin of Fujian in China.The HJ-1 satellite image acquired on December 9,2010 was utilized and NDVI index was calculated representing the range of vegetation greenness.Proper analysis units were achieved through segregation based on small sub-basins and altitudinal bands.Results indicated that the GWR model was more powerful than ordinary linear least square(OLS) regression in interpreting vegetation-environmental relationship,indicated by higher adjusted R2 and lower Akaike information criterion values.On one side,the OLS analysis revealed dominant positive influence from parameters of elevation and slope on vegetation distribution. On the other side,GWR analysis indicated that spatially,the parameters of topography had a very complex relationship with the vegetation distribution,as results of the various combinations of environmental factors,vegetation composition and also anthropogenic impact.The influences of elevation and slope generally decreased,from strongly positive to nearly zero, with increasing altitude and slope.Specially,most rapid changes of coefficients between NDVI and elevation or slope were observed in relatively flat and low-lying areas.This paper confirmed that the non-stationary analysis through the framework of GWR could lead to a better understanding of vegetation distribution in subtropical mountainous and hilly region.It was hoped that the proposed scale selection method combined with GWR framework would provide some guidelines on dealing with both spatial(horizontal)and altitudinal(vertical) non-stationarity in the dataset,and it could easily be applied in characterizing vegetation distribution patterns in other mountainous and hilly river basins and related research.
For preventing ecosystem degradation,protecting natural habitats and conserving biodiversity within the habitats,2588 nature reserves have been established in China at the end of 2010.The total area is up to 149.44 million ha and covers over 15%of Chinese terrestrial surface.Land-cover change,as the primary driver of biodiversity change,directly impacts ecosystem structures and functions.In this paper,180 National Nature Reserves(NNRs)are selected and their total area is 44.71 million ha,accounting for 29.9%of all NNRs in China.In terms of the ecosystem characteristics and their major protected object,all selected NNRs are classified into 7 types.A Positive and Negative Change Index of Land-cover(PNCIL)was developed to analyze the land-cover change of each NNRs type from the late 1980s to 2005. The results show that the land-cover of all selected NNRs types have degradated to a certain degree except the forest ecosystem reserves with a decreasing rate,but the rate of degradation alleviated gradually.The mean positive and negative change rates of land-cover in all core zones decreased by 0.69%and 0.16%respectively.The landscape pattern of land-cover in the core zones was more stable than that in the buffer zones and the experimental zones. Furthermore,the ecological diversity and patch connectivity of land-cover in selected NNRs increased generally.In short,the land-cover of 180 selected NNRs in China had a beneficial change trend after NNRs established,especially between 1995 and 2005.
Recently,important land use changes have occurred in the Black Sea coastal regions of Ístanbul due to urban growth and population increases.The objective of this study was to determine changes in land use in the Black Sea coastal regions of?stanbul between 1987 and 2007.Landsat 30 m satellite images from 1987 and 2007 are used in the study.The study area is 1000 m in width from the coastline to the land and the study has been carried out using the controlled classification method to classify areas into residential,agricultural, forest,bare land,brush/grassland,and lake/pond land classes.Land use changes between 1987 and 2007 were analysed in detail.Residential areas of the Black Sea coastal regions of Ístanbul increased by 122%over the two decades.Also an increase of 55%in agriculture areas was observed,while there were decreases of 26%in forest areas and 15%in free land. A 21%increase in the area of brush and grassland took place.Furthermore 79%of the study area was covered by residential areas in 2007.It is probable that pressure on the Ístanbul coastal regions will continue due to migraton and rapid urbanization.Therefore,Istanbul's Black Sea coastal regions should be maintained using a sustainable coastal management plan.
Historical database of National Soil Survey Center containing 1424 geo-referenced soil profiles was used in this study for estimating the organic carbon(SOC)for the soils of Ohio,USA.Specific objective of the study was to estimate the spatial distribution of SOC density(C stock per unit area)to 1.0-m depth for soils of Ohio using geographically weighted regression(GWR),and compare the results with that obtained from multiple linear regression (MLR).About 80%of the analytical data were used for calibration and 20%for validation.A total of 20 variables including terrain attributes,climate data,bedrock geology,and land use data were used for mapping the SOC density.Results showed that the GWR provided better estimations with the lowest(3.81 kg m-2)root mean square error(RMSE)than MLR approach. Total estimated SOC pool for soils in Ohio ranged from 727 to 742 Tg.This study demonstrates that,the local spatial statistical technique,the GWR can perform better in capturing the spatial distribution of SOC across the study region as compared to other global spatial statistical techniques such as MLR.Thus,GWR enhances the accuracy for mapping SOC density.
As important mechanisms of regional strategy and policy,prefecture-level regions have played an increasingly significant role in the development of China's economy.However, little research has grasped the essence of the economic development stage and the spatio-temporal evolution process at the prefecture level;this may lead to biased policies and their ineffective implementations.Based on Chenery's economic development theory,this paper identifies China's economic development stages at both national and prefectural levels. Both the Global Moran I index and the Getis–Ord Gi*index are employed to investigate the spatio-temporal evolution of China's economic development from 1990 to 2010.Major conclusions can be drawn as follows.(1)China's economic development is generally in the state of agglomeration.It entered the Primary Production Stage in 1990,and the Middle Industrialized Stage in 2010,with a‘balanced–unbalanced–gradually rebalanced' pattern in the process.(2)China's rapid economic growth experienced a spatial shift from the coastal areas to the the inland areas.Most advanced cities in mid-western China can be roughly categorized into regional hub cities and resource-dependent cities.(3)Hot spots in China's economy moved northward and westward.The interactions between cities and prefectures became weaker in Eastern China,while cities and prefectures in Central and Western China were still at the stage of individual development,with limited effect on the surrounding cities.(4)While the overall growth rate of China's economy has gradually slowed down during the past two decades,the growth rate of cities and prefectures in Central and Western China was much faster than those in coastal areas.(5)Areas rich in resources,such as Xinjiang and Inner Mongolia,have become the new hot spots of economic growth in recent years.For these regions,however,more attention needs to be paid to their unbalanced industrial structures and the lagging social development against the backdrop of the rapid economic growth, driven predominantly by the exploitation of resources.
The wide application of information and communication technologies(ICTs)has been argued to be critical to spatial transformation of firms.Recent advances in the studies along this line have challenged traditional location theory.The existing literature,however, focuses mainly on the impacts of ICTs on locational conditions and industrial spatial distribution.The dynamics behind such changes have not yet been given sufficient attention by ge- ographers.Given this background,this paper investigates the impact of new ICTs on traditional location theory and the dynamics of industrial re-location that are enabled by new ICTs, based on data collected from an investigation of 178 firms.The paper argues that the application of new ICTs has been a key location factor in the information age,and that the time-cost is becoming critical to the spatial organization of firms,particularly as a result of a shorter product life and mass customization,among other dynamics.
The study employs slope,aspect,relief degree of land surface,land use,vegetation index,hydrology and climate,as evaluation indexes to set up the Human Settlements Environmental Index(HEI)model to evaluate the environmental suitability for human settlements in the Shiyang River Basin.By using GIS spatial analysis technology,such as spatial overlay analysis,buffer analysis and density analysis,the environmental suitability of the human settlement spatial situation and spatial pattern are established to analyze their spatial distribution. The results show that the index of suitability for human settlements in the Shiyang River Basin is between 17.13 and 84.32.In general,suitability for human settlements decreases from the southwest to the northeast.Seen from an area pattern,the suitable region is mainly distributed in the Minqin oasis,Wuwei oasis and Changning basin,which are about 1080.01 km2 and account for 2.59%of the total area.Rather and comparatively suitable region is mainly distributed around the counties of Gulang,Yongchang and north of Tianzhu,which is about 1100.30 km2 .The common suitable region is mainly distributed outside the counties of Yongchang,Jinchuan and most parts of Minqin County,which are about 23328.04 km2 ,accounting for 56.08%of the total area.The unsuitable region is mainly distributed upstream and to the north of the river,which is about 9937.60 km2 ,accounting for 23.89%of the total area.Meanwhile,the least suitable region is distributed around the Qilian Mountains,which are covered by snow and cold desert and lie in the intersecting area between the Tengger Desert and Badain Jaran Desert.The total area is about 6154.05 km2 ,accounting for 14.79% of the total area.Suitable regions for human habitation are mainly distributed around rivers in the form of ribbons and batches,while others are scattered.The distribution pattern is identical to the residential spatial pattern.In addition,the relationships between HEI and other factors have been analyzed.There is a clear logarithmic correlation between the residential environment and population,that is,the correlation coefficient between the evaluation value and population density reaches 0.851.There is also a positive correlation between the resi- dential environment and economy,which reaches an evaluation value of 0.845 between the residential environment and GDP.Results also show that the environment is out of bearing with the existing population in Shiyang River Basin.Spatial distribution of population is profoundly affected by severe environmental problems,such as the expanded deserts,the hilly terrain and the changing climate.Surface water shortage and slow economic growth are bottlenecks for suitable human settlement in the Shiyang River Basin.Combining these problems with planning for construction of new country and the exploitation of local land,some residential areas should be relocated to improve the residential environment.
Environments in arid and semiarid regions are extremely sensitive to climate changes.High wind activity in these regions has resulted in an extensively developed arid geomorphology,but past environmental changes are poorly understood because of the absence of relatively high-resolution proxies.The accumulation characteristics of nebkhas, which have developed extensively in these regions,can be used as a method of reconstructing environmental changes.Here we summarized recent advances in research on the formation,development,and sediment characteristics of nebkhas and their significance to environmental changes in arid and semiarid regions.Based on the studies of our colleagues, we suggested that research on nebkha formation can provide distinct clues about environmental changes in arid and semiarid regions;however,continued studies are needed.
Actual evapotranspiration is a key process of hydrological cycle and a sole term that links land surface water balance and land surface energy balance.Evapotranspiration plays a key role in simulating hydrological effect of climate change,and a review of evapotranspiration estimation methods in hydrological models is of vital importance.This paper firstly summarizes the evapotranspiration estimation methods applied in hydrological models and then classifies them into the integrated converting methods and the classification gathering methods by their mechanism.Integrated converting methods are usually used in hydrological models and two differences exist among them:one is in the potential evaporation estimation methods,while the other in the function for defining relationship between potential evaporation and actual evapotranspiration.Due to the higher information requirements of the Penman-Monteith method and the existing data uncertainty,simplified empirical methods for calculating potential and actual evapotranspiration are widely used in hydrological models. Different evapotranspiration calculation methods are used depending on the complexity of the hydrological model,and importance and difficulty in the selection of the most suitable evapotranspiration methods is discussed.Finally,this paper points out the prospective development trends of the evapotranspiration estimating methods in hydrological modeling.
As geographic literacy training is an essential content for Chinese citizens' literacy education,national geographical education is one of the indispensable key aspects of that training.Because of China's vast land area and the significance of the regional differences,it is difficult for students to receive a solid education regarding China's geography.In 1902,the government established the geography curriculum and began to incorporate the concept of geographical regionalization to facilitate the teaching of China's geography by publishing the first syllabi,which was modified later and put into use in 1904.Since 1904,numerous geography textbooks have attempted to find an appropriate way to present China's geographical regionalization,as it is important for secondary students to have a clear understanding and appreciation for the different regional characteristics.Accordingly,the geographical regionalization content is divided into four main phases:1902 to 1927;1928 to 1948;1949 to 1986; and 1986 to the present.During these phases,the content related to China's geographical regionalization in secondary middle school geography textbooks has been gradually simplified and has adopted a more scientific foundation,thus leading to the present time where there are now four geographical regional areas.From this historical study,we find that while China's geographical regionalization has gradually matured,there are still some problems. For example,dividing the study into four regions to describe the panorama of China is too simplified,and the learning therefore becomes too scattered and haphazard,particularly given the new curriculum reform.
The 2012 Annual Meeting of the Geographical Society of China(GSC)was held on October 12-14 in Henan University,Kaifeng,Henan Province.The meeting was co-sponsored by the GSC and Henan Association of Science and Technology,and co-hosted by Henan University with a history of 100 years and Henan University of Economics and Law.A total of around 1300 geographers throughout China participated in this meeting and more than 800 papers including 560 oral presentations were submitted and discussed.During the meeting,20 young scholars were prized for their excellent papers presented to this annual meeting.