The existing finite element numerical simulation method of groundwater flow has some defects in the three-dimensional visual spatial analysis and the expression of numerical calculation process and simulation results. In order to solve this issue, the key steps of the finite element analysis process including the conceptual model construction, spatial discretization, hydrogeological parameters extraction and initial condition assignment are taken into consideration respectively. Based on the finite element method and 3D GIS platform, the method and technique framework of the groundwater finite element numerical simulation under 3D GIS are proposed with the supports of GIS spatial analysis algorithms and computer graphics theory. In addition to describe the technique framework, the core algorithms’ implementation details are given and the complete process of 3D GIS groundwater flow simulation is presented. The groundwater simulation example demonstrates that the proposed method and technique framework are capable of simplifying the finite element analysis process and improving the calculation efficiency of the model. The whole technique framework can be integrated into 3D GIS platform, and furthermore the visualization of simulation process and calculation results can be achieved eventually.

The mountainous regions of Southwest China, where Chongqing Municipality is located, has typical regional environmental characteristics such as cloudy fog and less sunshine. In order to realize the spatial simulation of temperature in this geographical environment, this study proposes a model for local regression considering terrain correction factor for solar radiation. In this model, the terrain correction factor is derived indirectly by fitting the spatial distribution of global solar radiation under undulating terrain. The model combines the Geographically Weighted Regression model, the Solar Analyst model, the improved Angtrom-Prescott equation, and the multiple linear regression method. Based on temperature, relative humidity, sunshine percentage, and global solar radiation of the meteorological stations, combined with DEM data with a resolution of 100 m×100 m, this model realizes the spatial simulation of temperature under the mountainous terrain. The model has good fitting accuracy and stability. The simulation accuracy of local regression term is much higher than Inverse Distance Weighting (IDW) interpolation and Kriging interpolation. It is also better than the traditional Multivariate Llinear Regression model based on latitude, longitude, altitude, sunshine percentage, and relative humidity. Further, 55 regional meteorological stations are used to verify the summer temperature simulation accuracy of a single year. The average absolute error is 0.59°C, and the errors of 38 meteorological stations are reduced after considering the terrain correction factor. The model performs well in spatial and temporal simulation of air temperature, which can reflect the influence of local terrain factors such as slope, aspect, and topographic occlusion on temperature, and has clear physical meaning. Based on the available observation data of meteorological stations, DEM, and the commercial software ArcGIS, this model is convenient to apply, especially suitable for cloudy, sunless areas like Chongqing and its surrounding mountainous regions.

As a basic system for the reform of the property right system of natural resources assets, the unified confirmation and registration of natural resources rights has also taken on the brand-new system goal of ecological protection and supervision in addition to the traditional function of publicizing the real right order. The dual purpose of the system is to cause problems such as uncertainty of the demarcation standard of the registration unit and vagueness of the legal nature of the registration object, thus jeopardizing the effectiveness of the system for unified confirmation and registration. Based on the embeddedness of the ecological value of natural resources in the realization of economic values, unified confirmation and registration should be located in the overall registration of spatial dimensions by re-recognizing the ecological relationship between various resource elements. Therefore, on the basis of integrating the current real estate registration system, it is necessary to clarify and improve the nested structure of the unified confirmation and registration of natural resources in terms of registration function (ecological supervision-ownership confirmation), registration object (ecological space-resource element), and operation logic (external administrative supervision-ownership self-restraint), so as to successfully realize the dual goal of confirmation and registration of natural resources rights.

该文以奈曼旗1995年~1999年的土地利用数据为基础，结合人口和国内生产总值增长的驱动作用，采用GKSIM模型对奈曼旗的土地利用变化趋势进行模拟分析。模拟结果显示，奈曼旗的林地面积将从1995年的171171 hm2增加到2015年的197363 hm2；以耕地和园地为主的农业用地面积基本稳定在18000 hm2的水平；草地面积在近几年的下降后基本保持稳定，约为98000 hm2；非农业用地持续增加，到2015年达到31000 hm2。其它用地面积从1995年的326759 hm2下降到302655 hm2。土地利用变化的基本趋势预示着，未来15a，奈曼旗的生态环境将在总体保持稳定的基础上有所改善。

The urban built-up area boundary is important basic information for urban studies, and is also the premise of the implementation of urban function space layout, the implementation of boundaries control. Accurate extract urban built-up area for urban construction, management and research has important guiding significance, but also reflects the city's comprehensive economic strength and the level of urbanization, one of the important indicators.The DMSP/OLS night light data has been widely used in the extraction of urban built-up areas. But due to the effects of saturated, diffuse, and low resolution problems, it is still a huge challenge to rely on the DMSP/OLS NTL mapping the urban built-up areas. In order to overcome the limitations of the data source itself, In this study, the application of hierarchical expert knowledge analysis, multi-source data extraction of the thematic information layer by layer into the extraction process, the construction of urban built-up area for the level of expert knowledge model to achieve the city built-area refinement extraction. The urban index （VANUI） was constructed by combining 250 m MODIS NDVI data with 1 km DMSP/OLS data. Based on the administrative boundary, the statistical area of the area is divided into the administrative boundary of each prefecture-level city, and the optimal segmentation threshold of each administrative unit VANUI feature image is calculated according to the regional segmentation method, so as to obtain 250 m urban boundary space information range. Meanwhile, Due to the low spatial resolution of the DMSP/OLS luminous data and the narrow range of light and light values, there is still a large gap between the optimal segmentation threshold and the built-up area. Therefore, this study proposed the maximum autocorrelation double threshold extraction method. The 30m Landsat 5 NDVI data were fused to obtain the maximum autocorrelation quadratic NDVI threshold in each 30m seed region by multi-scale segmentation of the regional threshold segmentation. According to the maximum autocorrelation threshold of each potential built-up area, each potential built-up area is revised one by one, and finally 30m urban built-up area is obtained. This paper takes the Beijing-Tianjin-Hebei region as the research area, the experimental results show that the total precision of extracting urban built-up area by multi-source remote sensing cooperative method is 92.9%, and it has higher validity and reliability in spatial distribution and statistical data. The results show that the results of the urban built-up area extracted by this method are not only the overall accuracy, but also the spatial extent of the visual interpretation, and the relative error of the statistical area in each prefecture-level city is small, which verifies the reliability and validity of the method in spatial distribution and statistical data, and avoids the error caused by subjective threshold selection. DMSP/OLS data can be used not only for urban area extraction, but also for the intensity and scope of human activities. Therefore, in the follow-up study, based on the identification of urban built-up area boundary, combined with the quantitative analysis of luminous data and evaluation of urban development area outside the expansion trend and internal dynamic changes for the DMSP/OLS luminous data to give full play to its effectiveness, Economic and historical values play a positive role in promoting.

Earth is always changing. Knowledge about where changes happened is the first step for us to understand how these changes affect our lives. In this paper, we use a long-term leaf area index data (LAI) to identify where changes happened and where has experienced the strongest change around the globe during 1981–2006. Results show that, over the past 26 years, LAI has generally increased at a rate of 0.0013 per year around the globe. The strongest increasing trend is around 0.0032 per year in the middle and northern high latitudes (north of 30°N). LAI has prominently increased in Europe, Siberia, Indian Peninsula, America and south Canada, South region of Sahara, southwest corner of Australia and Kgalagadi Basin; while noticeably decreased in Southeast Asia, southeastern China, central Africa, central and southern South America and arctic areas in North America.

In recent years, with the rapid growth of China's airports, the overlap of airports' market areas has gained increasing attention. The efficiency evaluation of airports' spatial distribution and spatial optimization of the airport layout have become a key topic in transportation geography. Based on the county-level population data in 2010, this study develops three indexes, namely population coverage ratio, population overlap ratio and redundancy ratio, and uses them to evaluate the efficiency of population coverage of civil airports during the 11th Five-year Plan (from 2005 to 2010) by comparing the three indexes of actual airports layout with the indexes from optimal models. Covering models, such as Location Set Covering Problem model and Maximal Covering Location Problem model, are used to identify the optimal airport locations and calculate the optimal indexes. The results indicate that the overall coverage ratio of China's airport system was greatly improved from 2005 to 2010, but still can be further optimized with an increase of about 27% both in 2005 and 2010. Therefore, more airports should be built in the central region of China to realize the optimization. The overlap ratio in 2010 is raised but closer to the optimal overlap ratio, which means the overlap of airports' areas was also improved from 2005 to 2010. This result also indicates that the lower population overlap ratio does not necessarily mean a better layout of the Chinese airport system, because to achieve maximum coverage is generally at the cost of a certain increase in the overlap ratio. There is a significant spatial variation in the overlap ratio. The overlap ratio of airports in the eastern region of China is higher than the optimal overlap ratio, but the overlap ratio in the central region of China is about 10% lower than the optimal overlap ratio. However, the airport redundancy increased from 2005 to 2010. One of the possible reasons is that the use of threshold distance in the airport planning improves the overlap ratio but also increases the redundancy ratio.

Heatwave has become an extreme meteorological disaster which occurred frequently during the summer. Moreover, heatwave could evidently affect the healthy conditions of residents. Thus, study the spatial pattern of heatwave health risk would be helpful for us to prevent from and respond to the impacts of heatwaves. Using the historically meteorological datum of Xiamen, this study built a database of heatwave cases and analyzed the basic characteristics of heatwaves in Xiamen. Taking a heatwave event occurred in 2010 as a case, we analyzed the spatial pattern of heatwave health risk by using both the remote sensing data and the demographic data. It is concluded as the following statements. (1) The intensity of heatwaves in Xiamen is quite low, but its frequency is rather high. An intensive heatwave occurred occasionally. (2) The regions with high health risk are located in Xiamen Island, lying from the northeast toward the southwest. The regions with the highest healthy risk are located in the northern and southeastern Jiangtou sub-district, Huli district, and the most area of Xiagang sub-district and Siming district. (3) The human health risk pattern of Heatwave is associated with the spatial distribution of environmental and demographic factors. Generally, this study promotes and extends the scientific knowledge on the health risk of heatwaves.

Based on the two dimensions of overall prosperity and achievement sharing,this paper constructs a common prosperity index system and applies the entropy method to measure the level of common prosperity in China at the provincial level from 2007 to 2020. This paper analyzes the spatial differences of common prosperity level using the Dagum Gini coefficient and portrays the dynamic evolution of its distribution using kernel density estimation. Moreover,it uses the Kaya identity and LMDI factor decomposition method to identify the driving effects of its dynamics. Conclusions are as follows: 1) The common prosperity level increased significantly on the whole and in three regions,which showed a distribution pattern of "decreasing from the east of China to the west of China". 2) The overall differences,intra-regional differences and inter-regional differences of China's common prosperity are narrowing,and the inter-regional differences are the main source of overall differences. 3) The level of common prosperity in three regions is characterized by strong unimodal aggregation,while the overall shows a trend of polarization. 4) The economic effect and equilibrium effect have significant positive driving effects on the improvement of China's common prosperity,the driving forces of social effect and efficiency effect are developing in a good direction.

Utilizing Landsat TM/ETM+/OLI imagery and digital elevation model (DEM) data, this study extracted the boundaries of glaciers and glacial lakes in Poiqu Basin, Xigaze City, Xizang Autonomous Region, China from 1990 to 2020 through the ratio threshold method and visual interpretation. The distribution and variation of glaciers and glacial lakes over three decades were analyzed, alongside the exploration of their co-evolution and response to climate change within the basin. The findings revealed: (1) A notable acceleration in glacier shrinkage within the Poiqu Basin over the last decade, with glaciers primarily situated between 5500 m and 6100 m. While the count of large-scale glaciers (≥10 km²) remained constant, small-scale glaciers (≤0.5 km²) exhibited an upward trend. (2) Both the number and area of glacial lakes witnessed a significant increase, with an expansion rate of 74.24%. Predominantly located between 4900 m and 5300 m, the expansion was more pronounced in larger glacial lakes (≥0.07 km²), whereas smaller lakes (≤0.03 km²) also saw a marked rise in numbers. (3) Glacial lakes connected to their parent glaciers emerged as the most significant type contributing to glacial lake expansion, registering a 72.08% increase. (4) The past 30 years have experienced a gradual temperature rise and a minor decline in precipitation. These climatic shifts, particularly the temperature increase and precipitation decrease, have been crucial in glacier retreat, while meltwater from glaciers has facilitated the expansion of glacial lakes. Through examining the distribution, changes, and interrelation of glaciers and glacial lakes in Poiqu Basin, this study aims to provide valuable data support for understanding glacier area dynamics and aiding in the prediction and mitigation of glacial lake outburst floods.

The characteristics of wetland landscape structure in watershed in the Naoli River the Sanjiang Plain are exhibited in three aspects. The first one is wetland landscape gradient characteristic in the longitudinal landscape structure of the watershed from the sources area of rivers to the lower reaches, which shows that wetland landscape types were differently distributed according to the topographic gradient and hydrological gradient and formed a wide riparian landscape corridor in the watershed; the second is wetland landscape gradient characteristic in the transverse structure of watershed with perpendicularity rivers in the watershed, which also shows that wetland landscape types are differently distributed in a topographic gradient and hydrological gradient and formed an extensively distributed wetland area in watershed's flood plain; the third is wetland landscape internal structure, which shows that many small mosaics or patches were distributed in the microscopic geomorphic units in the extensive wetland landscapes. The driving forces leading to substantial changes of wetland landscape structure in the watershed were identified as: 1) land reclamation has led to more than 75% of wetlands loss in historical periods and 98% of the lost wetlands direct conversion to agricultural lands in the watershed, which is the major reason for watershed wetland landscape structure changes; 2) drainage ditches construction for agricultural development and dikes construction for flooding prevention after the 1980s has led to wetland loss and fragmentation and landscape structure changes in the watershed; 3) changes in wetland hydrological condition due to agricultural development have led to wetland ecosystem degradation, as a result, almost all the remaining marsh wetlands in the plain were degraded to meadow wetland at present state.

This paper discusses by using two examples the calculating question of professor Fu Baopu's experimental formula for Mountain precipitation and points out that the improvement of the calculating method for this formula suggested by yan Yuhua and Lai Hongnian which was published on Geographical research 6(1) has a lot of questions. Between the calculating result of Fu's formula and the practical material of the two examples, there appear more differentiations.

Decomposition of litter plays an important role in carbon turnover and nutrients cycling in wetland ecosystem. Tide is the key feature for the estuarine tidal wetland. The wetlands of the Minjiang River estuary region are one of the major estuarine tidal wetlands in the southeast of China, and the Shanyutan is the largest wetland in the Minjiang River estuary region. Litter decomposition, nutrient dynamics and influencing factors of two native species (Phragmites australis and Cyperus malaccensis) and one exotic invasive species (Phragmites australis) were studied using mesh bag method in two sites under different tidal water submergence conditions. One site was near the tide ditch, and the other is far from the tide ditch in central Shanyutan wetland. The results indicated that: (1) Frequent tidal water submergence had no significant effects on the litter decomposition rates of three plants. (2) Frequent tidal water submergence accelerated the N and P loss of Cyperus malaccensis and Spartina alterniflora, however, it had little effect on Phragmites australis. (3) The order of litter decomposition rate was Cyperus malaccensis＞Spartina alterniflora＞Phragmites australis, with rates of 0.003166-0.005280 d 1, and the time of 95% dry mass of litter loss ranged from 1.56 to 2.61a. (4) C concentrations had only a little change, and the major pathway of C release was mineralization during the 280 days; there was an upward trend in N concentrations, at the end of the experiment, N content had a net loss and the major pathway of loss was mineralization; there was an obvious fluctuating downward trend in P concentrations at the end of the experiment, P content had also a net loss and leaching losses were responsible for much of P loss. (5) Litter quality was a main factor influencing the litter decomposition rates of the three plants. Litter decomposition rate of Cyperus malaccensis with the lowest C/P was the greatest.

The transformation and development of urban waterfront space is the key way to promote the optimization of urban space and the adjustment of industrial structure, which has become the main part of the current international urban renewal and redevelopment efforts, and a large number of relevant studies have emerged. Therefore, it is necessary to summarize the existing studies. Taking the relevant publications in the Web of Science and Science Direct databases from 1988 to 2020 as the analysis object, this study systematically examined the research results of the transformation and development of urban waterfront space abroad, summarized and analyzed the research contents and main conclusions from the aspects of the transformation process, mode, motivation and mechanism, and effect. The results show that international studies on the transformation and development of waterfront space mostly used qualitative methods to carry out descriptive analysis of cases, the research themes have shifted from paying attention to practical needs to exploring underlying academic issues and gradually diversified, and the research perspective increasingly emphasizes humanism and the concept of equality. Finally, considering the international research experience and domestic reality, this study proposed that in the future, China should change the research perspective and research object, pay attention to the comparative study of multiple cases in different regions, reveal the transformation process of urban waterfront space, simulate the transformation mechanism of urban waterfront space, and comprehensively evaluate the transformation effect of urban waterfront space, so as to optimize and improve the research system of urban waterfront space in China.

目前水温预报的降水资料严重不足，特别是无资料地区将很大可能利用卫星遥感反演获取降水信息，丹遥感资料提供的降水时间尺度往往较长，难以满足水文预报需求。论文提出了一种基于统计，针对独立降水事件，将长时段降水聚解为短时间尺度降水的方法。研究将此方法应用于史灌河七邻雨量站，分别聚解了七邻6h、3h、2h、1h降水为10min降水。研究表明，该方法计算简单，能保证模拟的总量同实际的完全一致，雨强同实际的基本一致，具有较好的区域适应性。图6表6参8

本文从地貌和气候两方面分析了四川大巴山区的自然环境特点，指出了山区的自然资源和开发利用中存在的问题。认为该地区资源丰富、潜力巨大，因该走综合开发、全面发展的道路。开发中要从生态经济的观点出发，明确以林为主的方向；要根据自然条件的垂直差异，发展“立体农业”；要利用山区的优势，寻找开发的突破口，迅速振兴山区经济。

An artificial Masson pinus forest has been chosen to measure the precipitation inside and outside of the forest, as well as stemflow.

Generally, in southern China with complex growing system, fragmentized and dispersed paddy field, and long-term overcast and rainy weather, the performance of using vegetation index (VI) time-series datasets derived from remote sensing imageries to extract multiple-cropping index was seriously constrained by the lower spatial resolution. Currently, the application of higher spatial resolution images can be the exclusive and effective way to extract the spatial pattern of different rice cropping systems annually in these regions. In this paper, firstly, the spatial distribution of paddy field in Poyang Lake Region (PLR) was obtained through one TM imagery interpretation. Secondly, the annual phenological calendar of various systems of paddy rice was defined with the agro-meteorological data. According to the significant characteristics that Normalized Difference Vegetation Index (NDVI) fluctuates sharply along with the growth process of paddy rice, map of NDVI for paddy field was derived from another TM image within the applicable time window. Then, different cropping systems of paddy rice were classified by means of Unsupervised Classification in Erdas Imagine 9.2. Finally, yield of each raster (100 m) was calculated with unit yield from local statistical department. The results showed that, late April to late June can be the time window to differentiate early rice and single-season rice, while early July till early August and middle September to early October could be the time window for the differentiation between single-season rice and late rice. Specifically, the planting areas of single-season and early/late rice are 3081.58 km² and 3602.97 km² in 2005, respectively, indicating that the multiple-cropping index is 153.9%. Single-season rice is generally distributed around the periphery of the built-up area, while double-season rice expanded along the delta. The total yield of paddy rice reached to nearly 16.5 million tons with a proportion of single-season to double-season approximating to 3 ∶7. The two seasons rice both had a higher yield in the lower reaches and delta area of the Ganjiang River.

石油供应与需求是当今世界关注的问题。西欧的石油资源十分贫乏。本世纪五十年代到六十年代,随着中东石油的开发,西欧大量增加原油进口。结果,石油在共能源消费结构中所占的比重迅速提高,西欧也成为世界上最大的原油净进口地区。在西欧各个地区的能源消费结构中石油所占的比重是不相同的。这一差异首先是由当地能源(特别是煤炭)的地理分布特点所决定的。煤炭资源比较丰富的英国、比利时、西德等国,能源消费结构中石油所占的比重较低。而当地能源十分贫乏的国家如意大利、葡萄牙、希腊等就主要依靠进口原油。西欧的原油供应主要来自西亚与非洲。在西欧各原油进口国与世界各主要原油出口地区间有着不同的组合关系。如北非原油主要到地中海沿岸各国,西非原油则多去北海沿岸国家,苏联原油则供应地中海沿岸及与东欧相邻的几国。这一组合关系主要与它们之间的相对位置有关。在“石油危机”后,西欧的石油消费量略有减少,而能源消费结构中石油所占的比重下降较多。未来的趋势是:由于其他能源利用的扩大,石油的消费量将继续下降。但在本世纪末以前,石油仍将是西欧最主要的能源。在西欧各国之间,由于能源资源与石油消费水平的差异,将表现出不同的变化趋势。

河岸(溪旁)的植被有助于调控沉积物及化学元素向江河的流失。滨海平原农田水域的研究表明,河岸林生态系统是良好的营养库,并能减少周围农田生态系统的养分流失。河岸林生态系统土壤和植被的吸收与运转,截获了农田流向河道的养分,如果定期采伐树木,那末河岸生态系统就能有效地起到短期和长期截获与贮存养分的作用,从而确保了养分的净吸收。

South Africa is China's largest trading partner and investment destination in Africa, especially in infrastructure construction. Study of the spatial distribution of South Africa's population is of great significance to the cooperation of the two countries. Based on the census data from 1996 to 2011, this paper describes the spatial pattern and evolving trend of the diverse population of South Africa with time series and cross section data between 1996 and 2011 at county level, based on population density analysis, spatial autocorrelation analysis, population gravity center model, shift-share analysis, and unbalanced index. Using the software platform of ArcGIS and OpenGeoDa, conclusions are made as follows. (1) Population density of South Africa has "high on east and low on west" features, and also has multicore clustering characteristics in metropolitan areas and port cities. (2) Population density varies significantly in different regions. Metropolitan areas and coastal port cities have high population densities, while central and western regions have low population densities. (3) In terms of trend in population change, population distribution in South Africa became more and more imbalanced from 1996 to 2011. The gravity center of population moves to the northwest of South Africa since 1996. (4) Shift-share analysis shows population growth rate have undergone "high-low-high" stages for the last 15 years. At provincial level, Gauteng andWestern Cape have been always the places with dense populations.

A milestone in the Year of Biodiversity is that the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization to the Convention on Biological Diversity(CBD)was adopted in the 10th Conference of Parties(COP 10)held in Nagoya,Japan,Oct 18- 29,2010.Traditional knowledge(TK)is a key issue in the Protocol’s text and its negotiating period.This paper aimed to protect TK by defining its concepts and categories and promoting benefit-sharing with TK’s holders.Based on the analysis for the TK concepts of relevant international organizations and conventions, in particularly on the author’s current years’research work on TK in the ethnic areas of China,this paper proposes the categories and the classification system for the TK associated with biological resources,i.e. (i)the knowledge for traditional use of agricultural bio-species and genetic resources;(ii)the knowledge for traditional use of medicinal bio-species；(iii)traditional technical innovations for bio-resource use and traditional practices for farming and living styles;(iv)traditional cultures such as customary laws and community protocols that are related to conservation and sustainable use of bio-resources;and(v) traditional geographically biological indicators.Furthermore,this paper introduced the provisions for access and benefit-sharing of TK and proposed to share fairly and equitably the benefits produced from use of TK with indigenous people,local communities and other kinds of holders such as a country for the ancient documented TK.In addition,aimed to the existing problems for traditional knowledge protection,the national strategy for TK protection was introduced and measures for TK inheritance,development,utilization and protection measures were put forward,which are significant for TK’s popularization and beneficial to local communities of the ethnic groups in China.

With Pukou District of Nanjing as an example, the article introduces SLEUTH cellular automaton model and adopts the Landsat TM/ETM+ remote sensing data in five study periods(the years of 1988, 1995, 2000, 2004 and 2008)to simulate the general situation of urban expansion of the study area with or without the planned cross-river channels.And the influence of the planned cross-river channels on the urban growth of riverside city is analyzed from the perspective of quantity increase of construction land as well as spatial growth.The research shows that:1) SLEUTH model, after adjusted and tested, could well simulate the quantity growth of construction land as well as its characteristics of spatial distribution in the study area, therefore, it could be fairly applicable to the research of urban expansion of the study area; 2) the construction of planning cross-river channel has a significant impact on accelerating the growth of riverside city, but its driving effect will gradually decline year by year.The newly increased construction land in the study area will rise by 48.05% and 62.33% in 2020 and 2030, and the contribution rate of planned cross-river channel is 20.67% and 17.50%, with a decreasing driven effect year by year, which is particularly significant in the street of Jiangpu, Dingshan and Yanjiang in "Pukou New Town".

Crop growth in Hedong rain fed agricultural region of Gansu Province mainly rely on the natural rain. Spring and summer drought is the main factor affecting the growth of maize. The monthly meteorological data of 13 meteorological stations in Hedong region from 1957 to 2012 were acquired. To investigate the temporal and spatial distribution of spring and summer drought in Hedong maize planting areas, we used SPEI index to reveal the trend, cycle, spatial change of drought and its relation with circulation in recent 56 years. The results show that: Both the spring and summer season in Hedong maize planting areas become dryer in recent 56 years, and the situation was aggravating since the mid 1990s. The variation of drought underwent three phases. Both the spring and summer season were slightly arid before the 1980s. Summer droughts were more severe than spring drought from 1980s to 1990s. After 2000s, spring droughts were more severe than summer drought. The drought cycles of spring and summer are 20 years and 14 years respectively. The periodicities of drought were mainly affected by the sunspot. There was a significant difference in the spatial distribution of drought frequencies before and after SPEI mutation. Low drought frequency area transformed into high frequency area after the abrupt change of SPEI, and the draught prone areas expanded. The main circulation factor influencing spring and summer drought in this area was ENSO events, especially on summer drought. The significant increase of ENSO events were the main reason of more serious drought in Hedong region in recent 20 years. When ENSO warm events occur, it tends to be drought in spring and summer in this area; when ENSO cold events occur, it turns from dry to wet in spring and summer in this area.

China has been experiencing unprecedented urbanization process. In 2011, China's urban population reached 691 million with an urbanization rate of 51.27%. Urbanization level is expected to increase to 70% in China in 2030, reflecting the projection that nearly 300 million people would migrate from rural areas to urban areas over this period. At the same time, the natural growth rate of China's population is declining due to the combined effect of economic growth, improvement in education quality, and modern social consciousness. As a result, Chinese government has loosened its "one-child policy" gradually by allowing childbearing couples to have a second child if either of them is from a one-child family. An accurate prediction of the future spatial pattern of population and its evolution is critical for a variety of key policy-making processes in China, such as industrial development, ecological conservation, industrial upgrading and transfer, and environmental protection. In this paper, a top-down method was developed to project the spatial distribution of China's future population with considerations of both natural population growth at provincial level and the population migration between provinces from 2010 to 2050. The results suggested that the overall spatial pattern of Chinese population is unlikely to change significantly over the next four decades. Shanghai, Beijing, Tianjin and Jiangsu will remain the top 4 provinces in terms of population density in China, and Xinjiang, Qinghai and Tibet continue to have the lowest density of population. China's population is projected to continue to concentrate in eastern coastal provinces. Population densities of Shanghai, Beijing, Zhejiang will peak in 2030, while that of Guangdong will keep increasing until 2035. Due to the large amount of moving-out labors and gradually declining fertility rates, population densities for Central and Northeast China will decrease from 292 persons per km² in 2010 to 253 persons per km² in 2050, exhibiting a downward trend. The majority of the western provinces, including Shaanxi, Chongqing, Guizhou, Yunnan, Sichuan, Gansu, Ningxia, Qinghai, Xinjiang, Tibet, Guangxi and Inner Mongolia are likely to remain sparsely populated, with an averaged population density no more than 100 persons per km².

It is of significance to study the effect of land use change on ec osystem service values.This paper aimed to provide decision support for sustain able use of resources and protection of eco-environment by assessing land use change and its consequent changes in ecosystem service values of Jilin Province .We obtained land use data by interpreting remote sensing images.Based on dyna mic data of land use in Jinlin,this paper analyzed changes in land use and ecos ystem service values using the ecosystem service value coefficients put forward by Costanza et al.In addition,coefficients of sensitivity were introduced to test the rationality of ecological value coefficients.Results show that from1 980to2000,area of rangeland,water bodies and wetlands decreased and oth er categories of land use increased.Due to comparatively small valuation coeffi cients(VC)of cultivated land and comparatively big VC of wetland and water bod ies,the increment in cultivated land could not offset the total decrement in regional ecosystem service values because of decrease in area of wetlands and wa ter bodies.Meanwhile,city sprawl has also led to loss of ecological values.T he total ecosystem service values of the study area reduced dramatically,from U SD12365.14×10 6 to USD10700.38×10 6 in period1980-2000.There was a13.46%net decline in annual va lue of ecosystem services in study area(i.e.USD1664.76×10 6 net decline in total ecosystem service values)and a0.72%decline per ye ar.In recent five years,the degradation of woodland,wetland and rangeland sl owed down because of enhancement of eco-environment protection.There was an 0.54%decline per year in ecosystem service values from1995to2000,w hile there was an0.78decline per year from1980to1995,which shows t hat the decline in ecosystem service values has been lessened in recent five ye ars.

Hydropower development and outward transmission in Tibet play a vital role in optimization of energy resource configuration and reduction of CO₂ emission in China. The low-carbon effects of hydropower development in Tibet were assessed, and fossil fuel consumption reduction and CO₂ reduction achieved by hydropower development in Tibet were analyzed based on net coal consumption rate, CO₂ emission coefficient and its dynamic change of fossil-fired power generation in different power grids. The results show that: 1) The fossil fuel consumption reduction and the CO₂ reduction achieved by hydropower development in Tibet have significant variations. During the period from 2006 to 2012, the fossil fuel consumption reduction and the CO₂ reduction achieved by hydropower development in Tibet were the most in 2011. 2) The fossil fuel consumption reductions achieved by hydropower development in Tibet were different significantly with different net coal consumption rates of fossil-fired power generation. The fossil fuel consumption reduction achieved by hydropower development according to net coal consumption rate of fossil-fired power generation in Central China power grid (CCPG) was the most, the fossil fuel consumption reduction according to net coal consumption rate of fossil-fired power generation in Northwest China power grid (NCPG) and Tibet power grid (TPG) took the second and the third place respectively, and the fossil fuel consumption reduction according to net coal consumption rate of fossil-fired power generation in national power grid (NPG) was the least. 3) According to different CO₂ emission levels of fossil-fired power generation, the CO₂ reductions achieved by hydropower development in Tibet were also different. Among them, the CO₂ reduction achieved by hydropower development according to CO₂ emission level of fossil-fired power generation in TPG was the most, the CO₂ reduction of hydropower development according to CO₂ emission level of fossil-fired power generation in NCPG and CCPG took the second and the third place respectively. 4) The fossil fuel consumption reduction potential and the CO₂ reduction potential achieved by hydropower development in Tibet were outstanding. According to net coal consumption rates of fossil-fired power generation in NCPG, CCPG, TPG and NPG, the fossil fuel consumption reductions achieved by hydropower development in Tibet in 2030 would be more than 75% of total fossil fuel consumption (1.379×10⁸ tec) of fossil-fired power generation in NCPG in 2012. Among the CO₂ reduction potentials according to different CO₂ emission levels, the CO₂ reduction achieved by hydropower development in Tibet according to CO₂ emission level of fossil-fired power generation in CCPG would be the least, but more than the carbon dioxide emissions of fossil fuel consumption in Argentina, Pakistan, Vietnam and other countries in 2013.

After the adoption of the policy of reform and opening-up to the outside world,many changes in politics,society and economy have taken place in the Yangtze River Delta region and have resulted in rapid expansion of urban area.Using multi-temporal remote sensing images,we analysed the spatial and temporal urban dynamic change pattern of the Yangtze River Delta region in the past two decades.The results showed that from the end of the 1980s to the year 2000,the main land use change pattern is the rapid decrease of cultivable land and forest area and the fast expansion of urban area.Urban land use in the Yangtze River Delta presents a concentrated expansion,typically from vegetation landscape to a mixed urban and rural landscape,i.e.,95% from farmland 1.8% from forest land and 1.5% from grassland.Using remote sensing image to categorize land use,monitor land use change,and calculate land use change transfer matrix is a promising method to show distributed spatial pattern of land use and land use dynamic change.There exist different constitutional proportions relating to land use dynamic changes between the first decade and the second decade.The urban sprawl speed is lower in the second decade than the first one.The land use dynamic change affects the eco-environmental change in this region.For example,the urban expansion pattern directly affects the local climate change and the air quality of this region.Analyzing the correlation between the spatial pattern of urbanization and eco-environment in this region,we found that the urban sprawl pattern is one of the direct factors affecting the spatial distribution of regional urban heat islands and spatial pervasion of urban air pollution.By comparing the relationship between the land use change pattern and eco-environment,we can provide sustained decision-making strategy for improving eco-environment,developing local economy,and promoting the social progress.