The mean annual discharge, sediment concentration and sediment delivery ratio in the period from 1970 to 1989 are evidently smaller than that in the period from 1954 to 1970. The relations between monthly mean discharge and sediment concentration are different comparing the two periods of time. These phenomena have been influenced by human activities in which the dam building has been the dominant factor since 1970. To discuss the dam effect on decrease of sediment yield a concept of efficient area of dams was advanced. The relation between the annual efficient area of dams and years was fitted. The results show that the varying trend of the relation curve is coincident with the variation of the sediment yield in the decade's distribution. Since 1990 the increase of the sediment yield has resulted in evident decrease of the efficient area of the dams in the Wudinghe River basin. It is necessary to build dam largely and rapidly for restraining the increase of sediment yield in the river basin. If we want the annual sediment yield in the river basin gradually decrease, the annual efficient area of dams must be gradually increased year by year.

Nabkha is a common kind of biological wind deposition geomorphy in arid and semi-humid desert, and sandy coast.The nabkha's form is a kind of dynamical balanced shape made by the interaction of regional plant, wind and sand in the specific developmental stage of nabkha. It can reflect eco-environmental characteristics and regularity of change in the region. In this paper, the change regularity and characteristics of nabkha's shape in different developmental stages have been discussed on the basis of statistical analysis on morphological data of nabkha surveyed in the basin of Hotan River, Xinjiang. Results indicate that there exist better correlations among length, width and altitude of all kinds of nabkhas, but there is difference in different developmental stages of the same typical nabkha and different typical nabkhas, and according to analysis on mathematical model of nabkha's morphological data, regional eco-environmental features and aeolian characteristics, the development of nabkha can be divided into the growing stage with all shape data covariation, the stabilizing stage with higher gradient, synergistic growth of length and width and plant being the main factor, and the declining stage with nabkha's length shortening and more complex relations among all morphological data. The long axis and short axis of all kinds of nabkhas are in synergic growth. The horizontal scale and height of nebkha show significant correlation. The geometric shape of nabkha is approximately semi-ellipsoid which has few difference in slope-length and slope-gradient between upward and leeward sides in the basin of Hotan River. At the growth stage, Tamarix nabkha mainly appears approximately conical, and at the mature and stable stage, it is approximately hemispherical. The shape of Phragmite nabkha is approximately semi-ellipsoid which has shorter and steeper upward slope and longer and lower gradient leeward slope. The shape of Alaghi nabkha presents approximately semi-ellipsoid which has longer and lower gradient upward slope and shorter and steeper leeward slope. The result can be a quantizing index for monitoring regional desertification or oasis enlarging.

Whether some basic principles exist or not that could guide those who are engaged in studying economic geography is a major concern. The author of the paper holds a positive attitude and tries to conclude them as follows. The first is that people would be faced with making location choices, which implies that economic geographers must design possible selected places to reflect the cost of location decision-making. The second is that making location choices is spatial optimizations and competitions for space, which shows basic behavioral criterion of economic actor. Why would people like to select locations? The third gives an answer,that is, there are differences in space, which come from both the nature and the social-economic system. And the impacts of the latter may strengthen or weaken difference from the former. Two principles followed are that economic factors have different sensitivities to distance, and that economic systems have the substituting functions to adjust inputs for distance and for others, which voice the key points about effects of distance. The spatial market principle and spatial critical point principle, the sixth and the seventh, are related to the analytic methods in economic geography. The eighth is that local or regional competitiveness depends on its advantages of production and service cost and location advantage. The last is the location policy principle, which shows why and how to formulate regional policies. The author deems that the conclusion of nine principles helps the teachers and students to get a better understanding of the key points in economic geography for the teachers and students. And it is also in favor of establishing common language and building common acknowledged theories in the area of academic research of economic geography. In addition, in the area of applied research of economic geography, it is beneficial for researchers to find and choose important and essential economic geography variables.

The world natural resources have been depleted both on quantity and types with the increase of population and economic development in recent decades and the regional ecological security problem is getting more and more serious. Central Asia is not only the neighboring region of China, but also has the similar climate characteristics, physical geographic settings and even the same ecological environmental problems of the arid zone of north easternpart of China. Both countries belong to ecological environment's fragile region in the world. In this paper, four different regions of Central Asia's per capita and regional total ecological footprint, ecological capacity, ecological deficit and ecological footprint pressure index (EFPI) were calculated and analyzed based on the concept and method of ecological footprint. And according to EFPI, the assessment on the ecological security of different regions in Central Asia was made. The analytical results showed that :1) the mean ecological deficit of Kirghizstan from 1992 to 2005 is 0.0900 ha/capita and mean EFPI is 0.9388, on the slightly unsafe ecological status.2) The long period mean ecological deficit and EFPI of Turkmenistan and Kazakstan are 0.3303 ha/capita, 0.8379 and 1.1327 ha/capita , 1.2320 respectively, with both regions on the relatively unsafe ecological status.3)The regional total ecological capacity of Ozbekstan decreased from 28807119 ha in 1992 to 28527138 ha in 2005,and total regional ecological footprint presented an increasing trend; the mean EFPI is 1.7540,on the unsafe ecological status. Based on the calculation results, Kirghizstan's ecological environment is relatively good compared with other regions in Central Asia, followed by Turkmenistan and Kazakstan, and the last one is Ozbekstan. In a word, all these four central Asia nations are in the unsafe ecological environment condition, only the unsafe degrees are different. This study results would have academic value for the comparative analysis of the ecological security or sustainable development assessment of other arid and semi-arid regions in China or in the world.

The hydrologic process is a very complicated nonlinear system, of which runoff is a very significant component.Single parameter is difficult to characterize the change in the daily runoff time series completely, while the multifractality method with singular spectrum analysis enables us to get more information about the nonlinear behavior of runoff. Based on long-term daily runoff records of Cuntan, Yichang and Datong stations, this article has studied the multifractal temporal scaling properties of the Yangtze River, and fitted the multifractal spectrum by the modified version of the multiplicative cascade model.The results revealed that (1) The discharge series of the Yangtze River is a similar multifractal, and the mulfiractality is caused by the long-term persistence.The long-term persistence of daily runoff may be related to the interactions between precipitation and underlying surface over various ranges of space-time scales. (2) The fits based on universal multifractal model describe well the scaling behavior of positive as well as negative moments in the 3 daily runoff records . The two parameters a and b obtained from the model can be used to calculate the width Δα of singularity spectrum, and the values of a, b and Δα can be regarded as 'fingerprints’ for each station, which can be served as an efficient test for the state-of-the-art precipitation-runoff models. (3) The comparison of the width Δα of singularity spectrum among these three stations revealed that there are spatial differences in the complexity of the daily runoff change on the Yangtze River. The complexity of runoff records on Datong is larger than those of the upper reaches of the Yangtze River, while there is no significant difference between Cuntan and Yichang. The factors contributed to the complexity include the drainage area, constitution of water quantity, the characteristics of precipitation and underlying sufrace, and so on.

The sensitivity analysis of primary factors affecting the forest Net Primary Productivity (NPP) is important to estimate NPP accurately. In this paper, the sensitivity of NPP to primary parameters of BEPS (boreal ecosystem productivity simulator) was explored using uncertainty and sensitivity matrix (USM) at Changbaishan Natural Reserve in southeast Jilin province, China. Three input parameters for BEPS (leaf area index, temperature and precipitation) were selected for single factor analysis. The analysis was based on an uncertainty and sensitivity matrix with two fixed parameters and the third one was given with a change of +/-5% (or 0.5 degree), +/-10% (or 1 degree) and +/-20% (or 2 degree) respectively. The result shows that in Changbaishan Natural Reserve, forest net primary productivity increases with the increase of LAI, drops with the rise of temperature, and has no obvious relationship with precipitation. The sensitivity analysis of different vegetation classes, including coniferous forest, broadleaf forest and mixed forest, was also done. We find the coniferous forest has a strong adaptability to environment and less effect on the environmental changes. This study was just performed at one of the parameters with pre-setting changes, while the other two parameters are fixed at true values. Definitely, any parameter will respond to the change of other parameter. Hence the net forest primary productivity will change with them. Therefore, in the future, we need to strengthen the research of changing more parameters than one simultaneously to study the sensitivity of NPP to input parameters.

In social and economic activities, people usually actualize their spatial activities on road networks. However, most research results were on the ideal condition that geographical space was a homogeneous one, and almost all spatial analysis methods are according to the metric of planar Euclidean distance, its drawback is quite obvious. This paper presents the principle and the constructing method of network Voronoi diagrams, and the application of ordinary Voronoi diagram and network Voronoi diagram to the delimitation of the market fields of 17 stores in Wuhan, Hubei Province, China. The main results are as follows: (1) The market fields in the inner city are quite small while the ones in the outer city are a little large. If the road density in a store trade region was low, its area would be small; conversely, provided the road density in a store trade region was high, its area would be quite large. (2) There is a more or less difference between the application results of the methods based on ordinary Voronoi diagram and network Voronoi diagram. If the road density of a region was high, the difference would be small; and vice versa, there was a great difference in a region with a low road density. This shows that the method of ordinary Voronoi diagram can be chosen as a substitute of network Voronoi diagram to define the market fields of a store system in case of a region with a high road density.

Methane is an important greenhouse gas with high warming potential, most of methane emit from various wetlands. Some studies on methane emission in wetlands were done, however, few studies were reported in China, especially on tidal marsh. Production of methane is the basis of methane emission, and is also the first step of methane emission influencing greatly the emission process.Hence, research on the fields is necessary. The Minjiang River Estuary wetland was one of the tidal wetlands, which is situated on the southeast seashore of China influenced by tide,the concentrations of soil water content, salinity and electron acceptors were changed, and the effects of variation of soil physiochemical properties on methane production were unknown. Phragmites australis was one of the main species in Minjiang River Estuary wetland, distributed on the intertidal belt, so our study took Phragmites australis marsh which is typical and representative as the study areas. The methane production potential from the Phragmites australis marsh soil of the Minjing River Estuary after the import of electron acceptors and salt was determined using an anaerobic incubation technique. The range of methane production potential in different soil layers was 0.0202-0.0871μg · g^-1 · d^-1, the average value was 0.0378 μg · g^-1 · d^-1, and the highest methane production potential occurred in the surface soil, differing significantly from other soil depths(P<0.05). Methane production potential was inhibited by electron receptors import. When the concentrations of three kinds of electron acceptors increased from 4 to 12 mmol/L, methane production potential all dropped gradually.The methane production potential after adding nitrate and ferric was significantly different from that of controlling soils(P<0.05), but there was no significant difference when adding sulfate. There was no significant difference when the different concentration levels of the three types 08 electron receptors were applied(P>0.05). The inhibited effect of the three electron receptors on methane production potential was nitrate>ferric>sulfate; and methane production potential was partly inhibited by salt. The methane production potential dropped when the concentration increased from 4 to 12 mmol/L. The difference was not significant between the methane production potential after adding salt and controlling soil, and also the three concentration levels salt import(P>0.05).

Supported by MSS images in the mid and late 1970s, TM images in the early 1990s and TM/ETM images in 2004, the spatial distribution data set of ecosystem types was acquired through analysis and distinguishment, then the dynamic changes of spatial pattern and structure of ecosystems in the Three-River Headwaters region were analyzed since the 1970s. The results showed that alpine grassland occupied the largest area in the Three-River Headwaters region, and the area of alpine grassland occupied 64.68% of the total land area and 99.58% of the total grassland area.Wetland, glacier and mountain permanent snow-cover were characteristic ecosystems in the Three-River Headwaters region, with marsh area occupying 26.09% of the total area of water and wetland ecosystem, and glacier and mountain permanent snow-cover area 9.02% of the total area of water and wetland ecosystem. As the characteristic ecosystems in the Three-River Headwaters region, wetland, glacier and mountain permanent snow-cover played important roles in providing stable water resource. During recent 30 years, the changes of ecosystem spatial pattern in the Three-River Headwaters region have been stable and rather slow, with an annual changing rate of farmland, forest, grassland, water and wetland, and hungriness ecosystem being less than 0.5% respectively, the least but stable in the Yangtze and Yellow river basins, even the whole country. The changes of grassland, water and wetland ecosystem have occupied a dominant position in the Three-River Headwaters region since the mid and late 1970s. The changes of grassland mainly occurred in the central and eastern parts of the region, dominated by reclamation of grassland and conversion of grassland into unused land such as bare land, sandy and salt land. And the changes of water and wetland ecosystem mainly occurred in the vast western and northern parts of the region, represented by conversion of water body into beach land and conversion of wetland into grassland.

Based on water, sediment and precipitation data from the upper Changjiang River and its tributaries, a study has been made of the temporal variation in suspended sediment concentration in relation with the variation in precipitation and human activities.The variations in suspended sediment concentrations in the main stream and tributaries are not synchronic, and some complicated variation can be seen.The variation in precipitation can only explain 15.86%~37.21% of the variation in suspended sediment concentration, and thus variation in precipitation is not the main cause for the variation in suspended concentration. Using the analysis of double-mass curve, the effect of human activities on the variation in suspended concentration has been studied. The suspended concentration of the lower Jinsha River increased ofter 1983.This can be explained by the large-scale mining and road and urban construction, which not only disposes huge quantities of soil and rock debris to the river, but also results in the reactivation and releasing of the previously deposited mass-wasting and debris flow materials. The double-mass curve for the Minjiang River shows three breaks, which may be explained by reservoir construction and deforestation and reforestation. The suspended sediment concentration of the Jialing River decreased after 1984 because marked sediment reduction effect has been achieved by soil and water conservation measures. The suspended sediment of the Wujiang River increased after 1967 and then decreased after 1983, the former can be related to the vegetation destruction that enhanced soil erosion and the latter to the construction of reservoirs that trapped sediment.Compared to the 4 tributaries, the suspended sediment of the main stream of the upper Changjiang River shows smaller variation in suspended sediment concentration. As the suspended sediment concentration of the lower Jinsha River increased after 1983 while that of the Jialing River decreased after 1984, they offset each other and thus the variation in the suspended sediment concentration of the Yichang station is much smaller.The results of a multiple regression analysis shows that the contribution percentages of the variation in suspended sediment of Pingshan, Gaochang, Beibei and Wulong stations are 28.5%, 12.6%, 44.2% and 14.7%, respectively.

An accessibility computing method based on grid partition and heuristic A ^* searching algorithms was put forward in the paper, which is used to research accessibility spatial distribution feature in the study area through computing each grid's accessibility. Traffic cost is an important element in accessibility computing. There are two approaches to stimulate grid traffic cost, one is approach of density of road network, and the other one is approach of relative spatial resistance for different land use status. The density of road network is anti-correlative with traffic cost. Land use has a close relationship with urban traffic, so grid relative traffic cost can be stimulated directly by integrating the two approaches, actual status of road and topological structure of road network was ignored. A computing formula of grid relative traffic cost was defined in the paper. The key point is how to compute traffic cost of grids path. Dijkstra algorithm makes sure to get the lowest traffic cost, but it must spend more searching space and time. Not only can A ^* algorithms improve searching efficiency, but also can add some heuristic searching information to make searching result more reasonable. The key of the searching process is the definition of heuristic evaluation function H, which is responsible for estimating traffic cost from intermediate grid to target grid. Usually, marching from one spot to another is constrained by two factors: distance and arrival angle. So Euclid distance and marching arrival angle are adopted to evaluate traffic cost. In application, in order to make computing result accorded with practice, more heuristic information can be imported into computing process. For verifying our research, a software package was developed with C# language under ArcEngine9 environment. A case study was implemented by using the package. Accessibility of business districts was selected as computing object in Guangzhou city. The computing result by using the method can provide a quantitative reference for urban planning of the city.

It is of great ecological significance to the characteristics of elemental migration and community composition in the process of secondary succession of the conifer and broad-leaved mixed forest.Taking the sample of Korean pine-deciduous mixed forest communities at various succession stages in Zuojia Nature Reserve, Jilin Province, this paper studied the characteristics of nutrient elemental migration through the litter and soil layer A and B and community composition of herbs, scrub of Corylus spp, Quercus mongolica forest, Quercus mongolica-Betula davurica forest and mixed forest communities, by means of field investigation and comparative analysis.The results showed that the habitat was altered from dry-hot to warm-humid, along with the succession from herb community to mixed forest community. Element migration also transited from organic matter aggregation in surface to a distinct down-movement of clays and nutrient elements. Environment changed from neutral to sub-acid.

Land use changes influence the distribution and structure of terrestrial ecosystems, and also change their carbon storage. Cultivated land, an important part of our country, affects not only the crop productivity, but also the spatial distribution pattern of vegetation carbon storage. According to the GLO-PEM model and by using the NOAA/AVHRR data acquired in 1988, this paper estimates the net primary productivity of the Huang-Huai-Hai Plain. Then the amounts of the vegetation carbon storage associated with the various land uses are estimated by subtracting the quantities of litter. The key findings show that there are differences in vegetation carbon storage among the various land uses and over space. The density of vegetation carbon storage in forest area is the biggest, and the smallest is the unused land. According to the decoded land use information from Landsat TM/ETM digital imagines, we traced the land conversions in the period between 1988 and 2000 and analyzed the changes between cultivated land and other land types and find it interesting that different land types can be transferred to each other. But the net change will be various. With the development of economy, built-up area gradually expanded, and the amount of cultivated land around the city were occupied. A total of 5.3 10⁷hm² of land were transferred to cultivated land in the Huang-Huai-Hai Plain. Based on the above data, we calculated the impacts of cultivated land conversions on the vegetation carbon storage. It is found out that that the vegetation carbon storage decreased by 0.25% due to the land conversions between cultivated land and other land uses. The cultivated land conversion to built-up area caused a decrease of 4.57 10³tC released to air. We overlapped the agro-ecological zones and the vegetation carbon storage, and calculated the total changes in every agro-ecological zone. The vegetation carbon storage of the Huang-Hai Plain decreased by 0.89 10³t. With the population increase, 59% of the cultivated land was transferred to residential area. This is the main reason for the substantial decrease in the vegetation carbon storage. The research results provide valuable information for the formulating of the carbon management policies at a regional extent.

The uncertainty problem in hydrological model is an important issue of scientific research at present, which covers three aspects of data, model structure and parameters.Parameter is one of the key roles in analyzing model uncertainty problem. The value of parameters depends on characteristics of a basin, but in fact it is difficult to obtain because there are few observation stations. In general, it needs to confirm parameters by several calibration methods including Genetic Algorithm, Simulated Annerling and Artificial Neural Network. So there exists parameter uncertainty problem. The generalized likelihood uncertainty estimation (GLUE) methodology is an effective approach to study uncertainty of parameters. In this paper, the uncertainty in Xinanjiang model is examined by employing GLUE. Based on the simulation results of daily data from Jiuzhou(1978~1987) and Lushi(1980~1988) basins, it is found that the phenomenon of "equifinality" exists among parameters groups for both of the basins. According to comparison result of scatter plots, parameters of Xinanjiang model can be classified into three groups: sensitivity parameters such as UM, EX; non-sensitivity parameters such as KC, CS and regional sensitivity parameters such as B, WM. The conclusion is favorable for understanding parameters of Xinanjiang model so as to provide valuable scientific information for simulating hydrological processes. Finally it puts forward the main contents on future uncertainties research in hydrological modeling.

It is of great importance to the study of the dynamic extension of a city and its peripheral towns for simulating, predicting, adjusting and controlling urban extension, and for rationally protecting the farmland and using land resources. The extension of Chengdu and its peripheral towns is studied here by using LANDSAT TM satellite images respectively acquired in 1987 and 2000. Firstly, The images are registered to the GIS data. Secondly, the Different Building Index(DBI) is formulated by LANDSAT TM7-TM4 on the basis of analyzing the remote sensing image mechanism of the cities and towns and their background, which reflects the situation of construction. The model of extracting Chengdu city and its peripheral towns from DBI image is formulated by the threshold method. The spatial data of Chengdu city and its peripheral towns for the two periods is extracted from the remote sensing images of the two periods by calculating DBI and applying the model. Thirdly, the sprawl data of Chengdu city and its peripheral towns are obtained by overlaying the spatial data of the two periods. Finally, the sprawl data of each analytical unit obtained by masking or overlaying the sprawl data with the administrative boundary, the third circular road and the highway around the city are analyzed. It is shown that the spatial data of the two periods can be effectively extracted by using DBI and the extraction model. The GIS technology is especially suitable for analyzing the sprawl of the city in each unit. The sprawl area in the highway around the city is about 11132 hm², which is 1.3 times of its original area. The sprawl area in the third circular road is about 6546 hm², which is 0.9 hm² of its original area, and mainly occurrs in the western, northwestern and southwestern parts, and most of which are external extensions. Between the third circular road and the highway around the city, the sprawl mainly occurs in the northwestern and southwestern parts,expanding mainly along the road. The sprawl pattern is mainly caused by the construction of high technology area and the spatial difference of investment and residential environment. In the five districts, Wuhou district is of the highest sprawl, which is 2.5 times of its original area. The sprawl area is over two times of its original area for each peripheral town, which is higher than the sprawl multiples of the city.

Soil and wheat samples in wheat-planted area in Beijing were collected for assessing the concentration and health risk of heavy metals.The results show that the average concentrations of As,Cd,Cr,Cu,Ni,Pb and Zn in the soils from wheat fields are 7.4, 0.165, 37.8, 20.3, 24.2, 14.3 and 70.1 mg/kg, respectively, which are lower than the baseline concentration of soil from Beijing. It shows that planting wheat did not definitely increase the concentrations of heavy metals in soil. The average concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in wheat are 0.032, 0.031, 0.967, 7.05, 0.293, 0.17 and 33.7 mg/kg, respectively. The concentrations of As, Cd, Cu, Ni, Pb and Zn are significantly less than the maximum levels of Food Hygiene Standards of China, and there is no significant difference between Cr concentration in wheat and the maximum Cr level of Food Hygiene Standards. Among the heavy metals, the accumulating ability of wheat for Zn is the best and that of As is the weakest.The average intake rates of As, Cd, Cr, Cu, Ni, Pb and Zn from wheat for people lived in Beijing are 0.005, 0.004, 0.136, 0.994, 0.041, 0.024 and 4.75 mg/(person day) and there is no significant risk caused by heavy metals intake for common residents in Beijing from staple and vegetables according to the average concentrations of metals and the average consumption.Among the districts of Shunyi, Fangshan, Daxing and Tongzhou, the largest wheat planted areas in Beijing, the average intake rates of Cr, Cu, Ni and Pb in wheat from Shunyi District are higher than those from the other three districts, while the average heavy metal intake rate of wheat from Fangshan is the lowest.

Changjiang Estuary, as a typical transitional zone between land and ocean, receives large quantity of organic materials from the Yangtze River and the ocean. In addition, the input of local materials such as detritus of macrophytes, photoplankton and benthic organisms makes it more complicated to trace the source and fate of organic matter in the estuarine and coastal tidal flat. The objective of this study is to trace the potential source of organic matter and the contribution of local environment to the organic materials by investigating the stable carbon isotopes in the organic constituents from the southern tidal flats of Changjiang Estuary. According to the features of physical geographical environment and the discrepancy in the effects of human activities in the study area, 9 typical sampling stations were selected along the southern Changjiang estuarine and coastal line. By measuring the stable carbon isotopes of organic matter in the winter (February 2006) and summer (August 2006) seasons of low and relatively high discharge, we analyzed the probable sources of organic matter from suspended particles and surface sediment. It is found that the ratios of stable carbon isotope in SPOM were respectively -25.8 ~-23.4‰ and -25.1‰~-22.9‰ in February and August, with the character of more negative in February. The spatial change of carbon isotopes displayed the trend of more positive in salt water than in freshwater areas, suggesting the mixture of marine and riverine organic matter. Due to the seasonal change of water discharge and marine phytoplankton blooming, terrigenous inputs exceeded marine inputs in winter and the reverse results have been found in summer. The ratios of stable carbon isotope in surface sediment ranged from -25.0 to -20.4 and -24.7 to -19.5 respectively in February and August. There was no obvious seasonal difference observed in isotopic compositions and the spatial change was similar to SPOM, suggesting the OM in sediment coming from the deposition of suspended particles. However, the autochthonous materials had also certain influence on the stable carbon isotopic compositions in organic matter. The input of sewage and tributary water impacted the carbon isotope in SPOM while the buried marsh macrophytes and benthic microalgaes contributed to the sedimentary organic matter.

In order to analyze the spatial structure and multi-scale characteristics of runoff time series in the Yarlung Tsangpo Zanggo River basin, the monthly runoff data at 6 meteorological stations in the study area from 1956 to 2000 are investigated. The periodic oscillation of runoff variation and the points of abrupt change at different time scales are investigated by using wavelet method in this study. At the same time, the main periods of each time series are identified by estimating wavelet variance, which is helpful to determine the spatial distributions of periodicity. Application of the Morlet wavelet function for the runoff time series has shown that the seasonal and annual trends of runoff change in the last 44 years were consistent at the scale of 15 years, and the abrupt change occurred mostly in 1957, 1967, 1976, 1983 and 1992. There are more points of abrupt and more numbers of alternation between low flow and ample flow at the smaller scales. There is an obvious periodic oscillation of 15 and 2 years for the first main periods for the seasonal and annual runoff variation, and 15, 6 and 2~3 years for the second main periods. The spatial distributions of periodicity for autumn and annual runoff time series are similar to some degree with those of winter and summer runoff, respectively. Both seasonal and annual runoff at any scales in the Yarlung Zangbo River basin will increase in the near future except the spring runoff in the Lhasa River basin at the scale of 2~3 years. The characteristics of runoff time series such as long-term trends, points of abrupt and periodic oscillation are consistent well with those of precipitation time series in the study area. It has been shown that the runoff recharge is mainly from precipitation in the Yarlung Zangbo River basin.

Aeolian landform, mainly distributed in northern China, has important impacts on regional ecological security and socioeconomic development. Although great successes were obtained in aeolian landform research in the past decades, timely monitoring of aeolian landform still need improvement because of its inconstant characteristics.In order to investigate recent situation of sandy deserts in China, an aeolian landform dataset was built by extracting landform information from Landsat 7 ETM imageries which were acquired in 2000. In the present study, we focused on aeolian landform in northern China, which is the main aeolian landform region of China, and analyzed characteristics of different sand dune types quantitatively. The results showed that: 1)Aeolian landform is distributed mainly in eight provinces. They are Xinjiang Uygur Autonomous Region, Inner Mongolia Autonomous Region, Qinghai Province, Ningxia Hui Autonomous Region, Gansu Province, Shaanxi Province, Jilin Province and Heilongjiang Province, among them Xinjiang and Inner Mongolia have the largest area and the richest diversity of aeolian landform. 2)As for the sand dune morphology diversity, sandy deserts in arid regions are much richer than in sandy lands of semi-arid regions. Among all landform types, some types are generally distributed in all aeolian regions, while some morphologic types are only limited in specific areas, resulting from actions of specific wind velocity, wind direction, vegetation coverage. 3)In consideration of dune activity, floating dunes are prevalent in deserts except the Gurbantuggut Desert and the Ulan Buh Desert which are mainly covered by inactive and semi-fixed dunes. In contrast with deserts, sandy lands are dominant by inactive dunes and semi-fixed dunes. This analysis summarized the recent situation of aeolian landform in northern China, and the dataset is important in aeolian landform periodical monitoring and morphologic evolution research.

Flow routing algorithm, which is often used to calculate the terrain parameters such as catchment area, specific catchment area, topographic wetness index and so on, is a key point in distributed hydrologic models, soil erosion modeling and other geoscience fields. The results obtained by the flow routing algorithms have distinct effects on hydrological and soil erosion modeling process. So evaluating flow routing algorithms has become a focus in these fields. In this paper, five flow routing algorithms, which are known as D8 (Deterministic eight-node), Rho8(Random eight-node ), Dinf(D-infinite), MFD ( Multiple flow direction algorithm), and DEMON ( Digital Elevation Model Networks), are selected to compare and analyze quantitatively on two Digital Elevation Model (DEM ) with 5m, 10m and 25m horizontal resolution respectively. Coefficient of relative difference, cumulative frequency distributions and XY scatter plot of the Total Catchment Area (TCA) are designed to evaluate the similarities within the selected flow path algorithms. Also the effect of DEM resolution on TCA, obtained from the selected five algorithms, is fully discussed. The results of the paper are summarized as follows: 1) differences between catchment area values estimated by the selected five flow routing algorithms were the greatest along side slopes area, and the differences decreased where the terrain became more convergent or along the channel; 2) the difference exists in any DEM with various resolutions, but is more sensitive to the high resolution DEM; and 3) multiple flow direction (MFD) algorithm is more suitable to estimate catchment area in complex terrain area than single flow direction (SFD) algorithm does that. So if the condition permits or accurate results are needed, high resolution DEM and fine MFD should be used effectively. This study also points out that the choice of flow routing algorithm has potentially important consequences for the calculation of upslope contributing areas, sediment transport capacity, topographic wetness, and several other topographic indices.

Vegetables have been reported as an important route of human exposure to heavy metals. This study aims to evaluate the health risks associated with ingesting heavy metals through vegetables for the general population of four districts (Shangba, Xiaba, Suoyikeng and Hewu) which were contaminated by mine exploiting and acid mine drainage irrigating in Dabao Mountain, Guangdong province, China. Soil samples (36), irrigative water (32) and vegetable samples (120) were collected from the 4 districts and heavy metals analyzed by atomic absorption spectrometry (AAS). The mean concentrations of Pb, Zn, Cd and Cu of the soils in Shangba village were 843.7, 2112.0, 2.66 and 586.3 mg/kg, respectively, and were 3.8, 10.6, 8.9 and 11.7 times compared to the tolerant limit level in China. The vegetable concentrations in Shangba village were 4.0, 1.1 and 5.6 times of the tolerant limit level of vegetables in China. While the mean concentrations of Pb and Cd in the other three districts were also higher than the tolerant limit level of vegetables in China. The heavy metal concentrations of soil and irrigation water and vegetables in the 4 districts were in the order: Shangba>Xiaba>Suoyikeng>Hewu. The average daily intakes (DI) of Pb and Cd in Shangba were 0.28 and 0.097 mg/d, which were 1.40 and 1.35 times of the provisional tolerable daily intake (PTDI) established by FAO/WHO. While the DIs of Zn and Cu in Shangba were below the PTDI. The DIs of heavy metals in the other three districts were also below the PTDI. The target hazard quotients (THQs) can be used to evaluate the health risks with heavy metals by vegetable concentrations consumed in inhabitants. The THQ of heavy metals of vegetables in Hewu and Suoyikeng were below 1, while the Pb and Cd in Shangba were more than 1, indicating that Pb and Cd were the key heavy metals which affected health risk of the inhabitants in this polluted area. It also showed that the inhabitants who lived near the contaminated river faced the adverse health risk. It indicated that health risk was caused mainly by AMD irrigating. Shangba villagers had higher health risk because they irrigated heavily contaminated water from Hengshi river, while Hewu villagers had less health risk by using contaminated water for irrigation. The THQ of Cd of Shangba village through vegetables was similar to that of Taiwan through oyster, while the THQ of Zn and Cu were lower than that. The THQ of heavy metals in Hewu was similar to those of uncontaminated areas.

Urban agriculture is a brand-new concept to innovate agriculture from the perspective of urban-rural harmonized development, which thus encourages planners and practitioners to understand the agricultural development in a broader urban-rural interactive system. The purpose of this paper is to compare the experiences of urban agriculture worldwide so as to stimulate and benefit China's urban agricultural development.By reviewing the facets of the developmental context, organizational form, production characteristics, marketing and agro-logistics, main function and policy building capacity, experiences in America, Britain and Germany in Europe, Japan, Korea and Singapore in Asia, Latin America and Africa are summarized. According but not limited to this, we argue that urban agriculture lays a promising and practical way for the project of China New Countryside & Agriculture and further contribute to coordinating the urban-rural development. In terms of the urbanization pace and nowadays situation, we may, however, need to discriminate the foci of urban agriculture between the city region area and the food-supplying area. The function of urban agriculture should be adjusted in the inner, middle and ex-urban areas. Enterprises and agricultural associations will be the major ones organizing urban agriculture, which requires specialization in the industrial chain. Agro-logistics is the weakest but in an urgent situation for the urban agricultural development in China. Policy capacity needs to be built on the agenda including urban planning, land tenure, property right, managing organization and technology innovation.

Islands play an important role in marine economic development,oceanic right ascription,and national defense. So,the study of the origin classification of islands is of not only theoretic significance,but is of also important applied value.Traditionally, islands are divided into continental island, oceanic island(volcanic island, coral island) and alluvial island in the ocean. This kind of classification can no longer adapt to match the new progress in the Earth Science today. According to plate tectonic theory and oceanic landforms system,the paper explains the origin of islands,and a new classification system of ocean island is proposed. We divide islands into geotectonic-geomorphic system island(continental terrace island,island of island arc,island of oceanic basin,mid-oceanic ridge island)and exoenetic force-geomorphic system island(sand island,coral island). At the same time,traditional classification is revised,and islands are divided into continental island,oceanic island(volcanic island and coral island),sand island and tectonic melange complex island. Classification Tectonic or deposition Type of islands (example) Endogenic system Continental terrace Coastal continental island( Newfoundland Is.)Swell symon continental I.(Taiwan Is.)Continental volcanic I.(Weizhou Is.) Island arc & edge oceanic basin Island arc continental island (Sumatera Is.)Island arc volcanic island(Kraktau volcano Is.)Subducting accretion island(Mentawai Is. Andaman Is.) Ocean basin & micro continental block Aseismic ridges volcanic island(Hawaii Is. Line Is.)Microplate islands(Greenland Is.)Oceanic volcanic island(Loyalty Is.) Mid-oceanic ridge Mid-oceanic ridge volcanic island (Iceland Is. Easter Is.)Structure fault island (Revillagigedo Is.) Exogenetic force-geomorphic system island Mud-sand deposition Estuary sand island (Chongming Is.)barrer island (Caofeidian Is. )erosion sand island(Dongsha Is. ) Biology deposition Coral island(Maldives Is.)

Remote sensing of urban heat islands (UHIs) has traditionally used the Normalized Difference Vegetation Index (NDVI) as the indicator of vegetation abundance to estimate the relationship land surface temperature (LST) and vegetation. This study investigates the applicability of Normalized Difference Moisture Index (NDMI) as an alternative indicator. This paper compares the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Moisture Index (NDMI) as indicators of surface urban heat island effects in Landsat imagery by investigating the relationships between the Land Surface Temperature (LST), NDMI, and the NDVI. Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) data were used to estimate the LST through the single window algorithm from three different months for the Zhujiang Delta area. Maps of NDVI and NDMI for three different data were generated from band 3, band 4 and band 5 of TM/ETM+ imageries, respectively. The relationships between the LST, NDMI, and the NDVI were analyzed supported by Geographic Information System (GIS). Our analysis indicates that there is stronger linear relationship between LST and NDMI for all three months, whereas the relationship between LST and NDVI is much weaker and varies by different months. With the change of seasons from summer to autumn, the linear correlation relationship between LST and NDMI was gradually lowered. This result suggests that NDMI provides a complementary metric to the traditionally applied NDVI for analyzing LST quantitatively over the three months for surface urban heat island studies using thermal infrared remote sensing in an urbanized environment.

Urbanization can be referred to as a process by which both human activities and productive factors concentrated from rural areas urban areas. As a result,modern cities act as the central places for human-being,not only in settlements and material consumptions,but also in social productions and environmental pollutions.Therefore,the changing patterns of agglomeration both in demography(which can be named as the demographic-urbanization)and in economy(which can be titled as the economic-urbanization)should be the two essential criteria for measuring national or regional urbanization,rather than the only one in demography.The findings,based upon the modern urbanization movement of 12 countries,including China,are salutary. First,development speed of economic-urbanization in all the countries is faster than that of demographic-urbanization. Second, but more important,as the role of secondary industry in modern urbanization process is going to be weakened,the influences of tertiary industry on modern urbanization is getting greater and greater. By contrary,the structural change oriented to the development of the secondary industry rather than that of the tertiary could be the major reason for a widening gap between economic- and demographic-urbanization in China.

Industrial location is a result of the interactions between economic, social and physical factors. Since the 1990s, factors affecting industrial spatial distribution in China have changed a lot, that is, the role of traditional factors like natural resources and transportation is decreasing while that of a number of new factors is increasing, such as inflow of foreign direct investment (FDI), agglomeration economy and development of innovation networks. As such, manufacturing activities have experienced turbulent spatial changes in recent years. The color-TV industry, as a major contributor to employment, productivity and output growth in the Chinese electronics industry, is a typical sector with rapid spatial changes in the last two decades. The main purpose of this paper is to explore the factors affecting recent spatial changes of the color-TV industry in China, and to identify its changing dynamics at different stages. Following a brief review on industrial location theory, this paper first summarizes the changing characteristics of the spatial distribution of China's color-TV industry from 1971 to 2005, by using the index of concentration. Then it analyzes major factors affecting the spatial distribution of the industry in three different development stages identified in the first step. The paper finds that, in recent transition from the central planning economy to a market economy and from a closed economy to one integrated more and more into the global economy, major factors affecting the industry's location have changed from government policy and intervention to corporate strategies to cope with intensified market competition and to inflow of foreign direct investment. China has a diverse, complex and rapidly changing economy. The paper offers a case study to understanding recent spatial changes of manufacturing activities in China, which is an area worthy of further study in the China's context.

Poyang Lake, which lies to the east of Mount Lushan in Jiangxi, is the biggest fresh water lake in China. It is also one of the abandoned lakes of the Yangtze River. As it is in the eastern monsoon area, it has a line vision in winter and a vast expanse in summer. Large areas of sandy hills appear around the Poyang Lake and the riverside of the Yangtze Rriver in the Hukou-Pengze section. They are well sorted and always come to 40 to 140 m high, looking like a desert in East China. Lots of scientists have done research in these sandy hills since the mid-20th century. They started with the formation and evolution of these sandy hills, and some of them analyzed the ancient climate change by the magnetic properties of sand samples. Shaling sandy hill in Xingzi which lies on the west shore of Poyang Lake is one of those sandy hills. After field investigation and collection of 26 sandy sediment samples in March 2005, we used sifter and laser granularity to measure their grain size. We also use ¹⁴C dating and thermoluminescence dating for three samples. Based on the field investigation of the landform and physiognomy, we classified these sandy sediments in Xingzi into seven different kinds and four periods of aeolian sandy hills. Those four aeolian sandy hills periods are 95 kaB. P. Old Red Dune, 46 kaB. P. Red Dune, 27kaB. P.~15kaB. P. Yellow Dune and 250 years Modern Dune. The other three kinds of sediments are secondary deposit on valley bottom, wind-erosion residual deposit on the lake shore and loose aeolian sediments on the Yellow Dune surface. As the wind power is the main driver of sand, the grain size of these aeolian sediments can show the wind power for the time when they deposited. We compared the grain size of the sand samples and come to the conclusion that wind power in these four periods can be arranged by Yellow Dune, Modern Dune, Red Dune, and Old Red Dune in a descending order. By comparson of the sediment series with the deep-sea oxygen isotope curve change, the Old Red Dune period of Poyang Lake is in the late Wurm glaciation (MIS5b), Red Dune period is in the middle Wurm glaciation (MIS3), Yellow Dune is in the last glacial maximum (MIS2), and Modern Dune is in the Little Ice Age. This result accords with the research result of sandy hills of this area by other scientists and can be compared with the global change in stade since the last interglacial stage and show the change of winter monsoon in Poyang Lake area.

Braess' network can be regarded as a significant metaphor of human geographical phenomena. By means of this simple model, we can reveal many important geographical principles. Based on the problem of traffic assignment in Braess' network, an integrated analytical process is propounded in this paper for efficiently exploring complex geographical systems. For simplicity, only the linear Braess' network without the third expressway is taken into consideration. The question is as follows: how the traffic flow is assigned between the two routes which have odd symmetric structure.Six methods are exerted to solve this problem, including Lagrange multiplier method (LMM), linear dynamical analysis, numerical simulation, numerical computation, Markov chain, and entropy-maximizing method. In the first place, Lagrange multiplier method is employed to give a preliminary solution. Secondly, a pair of linear dynamic equations is constructed for making deep analysis.The dynamic equations are utilized to make numerical computation and simulation. Further, Markov chain is used to make a prediction analysis.All the five kinds of analysis reach the same conclusion by different routes: the traffic flow should be averagely allocated in the two roads.Finally, the method of entropy-maximizing is employed to bring to light the theoretical foundation of average assignment of traffic flow in the Braess’ network.The entropy-maximization of geographical systems suggests the most equity for individuals and efficiency on the whole.All the six methods can be integrated to solve a problem from multifarious views of angles.If the conclusions drawn by different approaches are consistent with each other, the question is clear.However, in practice, some conclusions are not very clear, or even a conclusion based on one method may come into conflict with another one based on a different method.In this instance , the analytical process of multi-views of angles will help us solve the problem more efficiently and rapidly.

This study identifies the national benchmark industrial clusters, including both manufacturing and non-manufacturing clusters, using the 2002 national input-output table of China. A set of 22 industrial clusters are derived through combining an algorithm for defining a strength-of-linkage measure for all pairs of input-output sectors with application of a standard clustering algorithm. The national benchmark industrial clusters can be used as cluster templates in subsequent regional analysis. In this study, the template clusters are used to analyze the manufacturing sector of Beijing, and particular attention is focused on the electronic and telecommunication equipment cluster of Beijing. We find that there are three relatively large and highly specialized manufacturing clusters in Beijing, which are electronic and telecommunication equipment cluster, motor vehicles and equipment cluster, and electronic component and device cluster. For the electronic and telecommunication equipment cluster, Beijing is highly specialized in telecommunication equipment production and other electronic and telecommunication equipment production sectors. The spatial analysis shows that the electronic and telecommunication equipment cluster of Beijing is highly concentrated in the suburban area, mostly in Chaoyang, Haidian and Daxing districts.

This paper pays attention to the time-space evolution of FDI in Sichuan Province from 1991 to 2005. Based on the panel data of enterprises' numbers of all kinds of foreign investment in Sichuan Province in 1991, 1996, 2000 and 2005, the research shows that the industries in which the foreign enterprises invested are gradually expanding in this period, such as electricity, transportation, warehousing and telecommunications industry, wholesale and retail trade, real estate, tourism, mining industry in 2000, and remained unchanged from 2000 to 2005. However, investment focuses on the manufacturing industry. As to the spatial structure, the general spatial distribution is convergent notably from 1991 to 2005. But there are micro-scale changes in different periods of time. In the early 1990s, the 6 inner districts of Chengdu are the main ones in which the foreign capital invested, in addition to the suburban counties of Chengdu, Deyang and Mianyang are not prior areas, and other areas like Nanchong, Guangyuan at Leshan are the main ones. But in the mid-1990s, the foreign capital invested to key areas shows a spatial distribution pattern oriented to the Baoji-Chengdu,Chengdu-Chongqing and Chengdu-Kunming railways. And then, foreign entrepreneurs give first priority to Chengdu, Mianyang, Deyang and Leshan in the end of the 1990s. In the early 21^st century, there are only three prior areas including Chengdu, Deyang, and Mianyang. And there is a notable trend that industries in foreign capital invested enterprises agglomerate in inner districts of Chengdu including manufacturing, construction,agriculture,and all of the other tertiary industries except tourism. Besides, lots of FDI enterprises of manufacturing, agriculture, whole-sale and retail, real estate gather in the suburban districts of Chengdu, particularly, the amount of manufacturing enterprises increases steadily. But anyway, Mianyang, Deyang and Leshan are the important areas FDI entrepreneurs pay attention to, especially manufacturing and whole-sale and retail in Mianyang, manufacturing in Deyang, tourism in Leshan, but less FDI in other areas in any industry. The striking convergence of "Chengdu-oriented" of FDI in this period shows a polarization effect in the process of economic development in Sichuan Province. As a growth pole, Chengdu gets more favorable and effective policy supports from the higher authorization of Sichuan Province in competing with Chongqing since 1997, therefore, lots of fund has been invested in infrastructure construction, such as highways. On the other hand, Chengdu is the most developed area both in economic and social services. Besides, there are lots of excellent managers, R&D personnel and skilled hands, and a great potential market. All of the above are attractive to all kinds of FDI enterprises. In addition, the FDI invested enterprises demonstrate their development to the following ones and give them hopeful actuation effect.