Urban planners usually faced the problem of how to visualize the regional structure of urban with a quantitative method when the relationships among cities are complicated. Representing the regional structure of urban system with points (cities), lines (segmentation), and polygons (describing the influence area of cities), this article constitutes an analytical approach for identifying the spatial structure of cities in a region. A three-step procedure was proposed. First, cities with advantageous scales, good transportation conditions, and social and economic impacts in the region are chosen as critical nodes in the urban system, which are also considered to have potential for further development. Second, with a multi-scale analysis method, the spatial relation of the cities represented by such indices as traffic distance, time and cost, regional disparity, hours and the people, goods and capita are explored, whereby the cities are depicted as points on a Euclidean space, the distances of which reflecting the intensity of spatial interactions between cities. Accordingly, the concentration and departure of cities can be interpreted from the redefined locations. Third, the spheres of influence of the cities are examined, and the overall spatial pattern of the region, such as core, cluster and belt structures, connection and expanding directions, is clarified. The above method is applied to cities in the Xijiang Economic Region in Guangxi Province, China. The changes of urban structures over three periods are revealed, namely, when intra-city transportation mostly relied on low-hierarchy road and railway (before the 1990s), when express highways became the dominant (in the 2000s), and when a comprehensive transportation system consisting of highway, high-speed train and waterway transportation is put to use (under construction right now). It is found that, with the development of transportation system, connections among cities varied dramatically. For example, the city of Wuzhou was fairly isolated in the 1990s due to lack of railway connection with other cities, but in the 2000s, the distance was shortened by express highways and this trend will be further enhanced in the future. As a result, a triangle core and a belt structure will form in the region. The example demonstrated that the proposed approach is an effective tool for analyzing and predicting the development of regional spatial structures.
Tourists’ spatial behavior is one of the most important research fields of human geography. The existing studies have focused on the tourists’ spatial behavior of single urban destinations and scenic spots, few about tourists’ spatial behavior in the whole metropolitan area. This paper analyses the domestic tourists’ spatial behavior patterns of the Zhujiang River Delta metropolitan area, which belongs to one of the most developed areas of tourism in China. Though it is difficult to acquire practical data on tourists’ spatial behavior, tourist route is a good choice due to its convenience and completeness. Therefore, based on the national top 100 travel agencies’ itineraries of the main domestic tourist source markets of the Zhujiang River Delta metropolitan area from 2009 to 2011, the paper describes a detailed study of the tourists’ spatial behavior patterns and the urban destination types of the Zhujiang River Delta metropolitan area. Firstly, it is found that base-camp pattern and full loop pattern are the main spatial behavior patterns as a whole. Different tourist markets show different spatial behavior patterns. Tourists from Guangdong Province mainly choose single destination pattern and Hong Kong-Macao loop pattern, while tourists from the remaining markets mostly use other travel modes, such as base-camp pattern, en-route pattern, regional tour pattern and full loop pattern. Secondly, there is a big difference in the occurrence frequency of each city in itineraries, and it presents a three-level hierarchical relationship. In view of tourism destinations, Hong Kong and Macao are the most popular destinations with tourists which have the maximum occurrence frequency in tourists’ routes, up to 792 and 634 respectively. The secondary destinations selected by tourists of the Zhujiang River Delta metropolitan area are concentrated on Guangzhou, Shenzhen and Zhuhai. The occurrence frequency of these cities has reached more than 300. The rest of 6 cities are regarded as the third destinations because their occurrence frequency is less than 100. The type of different cities in itineraries is different between the Great and the Small Zhujiang River Delta metropolitan area, as well as among the different markets. According to this, the spatial behavior pattern figure of tourists from each market is obtained. Finally, a comparison about the number of itineraries, spatial behavior patterns, along with cities’ occurrence frequency and their types is made between the Great and the Small Zhujiang River Delta metropolitan areas. We thus conclude that Hong Kong, Macao together with the Zhujiang River Delta region have gradually become a closely connected overall in tourism development, however, there still need time to realize tourism integration for this three places.
In the context of globalization, the localization and delocalization among economic activities have been alternately affecting the spatial pattern of regional manufacturing industry, and lead to a wide range of social impact on the industrialized regions. The delocalization among economic activities not only is the spatial transference of production activities, it also is the process of functional integration brought by the departure and recombination of firms supply chain in different spatial scales, besides, it affects the forward and backward linkage, social capital and employment of localization industry at the same time. Nowadays, the research on firms delocalization mainly centralized in Europe and America, however, related research in China is too poor to be adapted to realities of China's regional economic and social development. In the last few years, sorts of foreign trade and processing firms in costal area of China have been captured by global traders or brands, and as a result, it produces the phenomenon of delocalization passively which leads to a complicated and profound influence on the evolution and upgrading of a local production network. Therefore, to research into the delocalization of foreign trade and processing firms in costal area of China plays a significant role in theory and reality. On the basis of European and American research reviews, the article thinks that in the context of global production networks, the tension force of network power and the stickiness of social capital are the main impetuses of firms delocalization. The interaction between the two forces above results in two different extents of dependence on the network power, namely in equal and in unequal, then lead to different forms of firms delocalization. Different forms of delocalization make different influences on firm economic performance and local economic agglomeration, and different forms also produce differences between local production networks. Finally, the article reflects on the delocalization of China's costal foreign trade processing industry and preliminary interprets its transformation and upgrading. It presents that in the context that the unequal dependence existing in the global network power can not be changed easily and properly, the firms in China’s costal foreign trade processing industries face the same questions: how they can take the positive and flexible measures to deal with the situation that the firms are used and controlled by the multinational corporations; how firms can finish the effective structure upgrading by using global connections to pass and absorb the knowledge in the global links and so on.
This article established the Inbound Tourist urban network that is linked by the model of tourist economic interrelationships employing GIS. Then the spatiotemporal evolution characteristics of Top1, Top5, Top10 networks in 1997 and 2010 were studied. The conclusions can be drawn as follows: 1) The network size is shrinking, but the maximum runoff and average runoff significantly grow, and the maximum runoff has occurred between Guangzhou and Shenzhen. 2) The agglomeration effect in a few core cities is more prominent. The structure of China inbound tourism is at the stage of core polarization, showing an overall “L” shaped distribution which means “the agglomeration effect of tourism in the eastern China is strong, but that in central and western China is weak”. Beijing, Shanghai, Guangzhou were the first class node cities, whose agglomeration effect significantly increased, Xi’an and Guilin were declined, while Shenzhen and Tianjin raised in 1997 and 2010. Agglomeration effect of cities in the eastern China was more obvious, while it declined in central and western China. The in-degree of cities in the western China was significantly higher than that in central China, but this advantage was reducing. That in the central China grew, but the economic interrelationship did not significant grow, still obviously lower than that in cities of the eastern and western China; 3) The in-degree and the strength of economic interrelationship were not proportional, Beijing’s in-degree was the highest, but its economic interrelationship was ranked only fourth, behind Guangzhou, Shenzhen and Shanghai. The first reason is the cities’ spatial distribution density, and the other is that the inbound tourism level of the two regions is very high, coupled with its relatively close distance. This also resulted in Zhuhai and Wuxi’s in-degrees were not high, but the economic interrelationships were very close; 4) From the bidirectional flow within the region and between regions, it is found that within the eastern area, the economic interrelationships are the highest and the most important relationship all over the country. The centers of the eastern China are Shanghai, Guangzhou, Beijing and Shenzhen. The centers of the western China are Xi’an, Chengdu, Chongqing and Guilin, whose relation with cities in the western China is very close, but that with other areas is not close. The centers of the central area are Changsha and Wuhan, whose relation with cities in the western is not close, but that with other areas is very close; 5) According to the network structure we can divide China inbound tourist urban into three systems: Beijing system, Shanghai system and Guangzhou system, which displays the patterns of “three centers, several cores”. Three centers are the first class node cities, Beijing, Shanghai and Guangzhou. Several cores are the second node and third node cities. The several cores of Beijing system are Tianjin, Xi’an, Qingdao and Dalian, the several cores of Shanghai system are Suzhou, Nanjing, Hangzhou, Changsha and Wuhan, and the several cores of Guangzhou system are Shenzhen, Zhuhai, Xiamen, Fuzhou, Chengdu, Chongqing and Guilin.
The short-term forecasts on economic and environmental indicators of Shenyang Economic Zone in 2009-2015 were made by choosing ARMA model. Then, the coupling relationship between economy and environment was simulated using coupling coordinate model. The ARMA model is one of the most popular time series models currently and requires a large sum of data with a minimum of 50 samples. In accordance with the principles and modeling steps of time series analysis, this article compared the pros and cons among models by model order determination, established the optimal ARMA forecasting model of economic development and environmental transformation respectively. It was found that, the predicted error of ARMA model was smaller and the effect was better. The economic indicators of the study area kept growing. The environmental indicators also gave a good trend with the positive indicators growing and the negative ones decreasing in various degrees. However, the coupling degree between economy and environment represented a declining tendency from 2010 which was mainly owing to the intensified environmental pressure from fast economic growth. The result told that there was still contradiction between economic development and environmental degradation and the contradiction kept circulating from ease to sharp and backward constantly. This research provided practical value for the management and adjustment of the contradiction between economy and environment in Shenyang Economic Zone. The coordinated development degree was directly affected by the scale of economic development and level of environmental construction. Thus, in order to improve the sustainability of economic development in Shenyang Economic Zone in the future, the environmental construction was as crucial as economic development. More projects from economic perspective should be taken as the adjustment of economic structure, reduction of energy consumption and increase of economic revenue. A series of positive measures should also be taken for the improvement of environment, such as improving resources utilization rate, strengthening cleaner production and promoting environment-friendly industry.
China is undergoing rapid advance of industrialization and urbanization. A large number of input in new construction land provide a strong support for the sustained rapid growth of investment in the whole society, and the continuous growth of investment has become an important driving force to spur economic growth. The moderate input in land factor is the basis to guarantee urbanization and economic development. The over-reliance on land for development will inevitably lead to a decline in the amount of arable land, not only endangering food security and the achievement of guard-line objectives for 1.2×103 km2 of arable land, but also having a major impact on the terrestrial carbon cycle and ecological system changes, which involves compensation, resettlement of landless peasants and other social issues. Accordingly, the accurate control on the contribution of construction land expansion to economic growth can help the management understand the land value in a scientific way as well as correct and abandon the wrong ideas to exaggerate economic value of the land. Based on the statistical data and C-D production function, the economic contribution rate of construction land of Anhui Province from 1997 to 2011 was quantitatively measured with the method of least squares regression, and its Logistic curve was explored. The results showed the findings in the following. 1) In the study period, the elastic coefficients of input factors, i.e., capital, labor and construction land, against the total output value of secondary and tertiary industries were 0.469,0.801 and 0.369 respectively. 2) The economic contribution rates of input factors, i.e., capital, labor, construction land and scientific progress, were 52.31%,22.9%,20.74% and 4.05% respectively. 3) The Logistic curve of construction land expansion fitted with economic growth occurs when the total output value of secondary and tertiary industries was 274.4 billion yuan(RMB) in 2002. From 1997 to 2002, the economic contribution rate of construction land increased rapidly. From 2002 to 2011, the rising speed of economic contribution rate of construction land slowed down and tended to be steady. 4) The economic contribution rate of scientific progress tended to increase steadily but in a relatively low value. These results can not only provide a reference for the directional transition of economic development in Anhui Province from land and other factors to technological innovation as well as similar researches at the provincial scale, but also lay a scientific basis for the development of differentiated adjusted land policy and the protection of arable land resources in different stages.
With the rapid development of China’s economy, China's total carbon emissions in 2011 have exceeded American’s and claimed the top spot in the world. The study on the influence factors of China's carbon emissions has been a hot international issue for a long time. Since China is currently in a critical period of national economic transformation development, it is particularly important to handle the relationship between carbon emissions reduction and economic development. The studies about the relationship between carbon emissions and economic growth have been performed from different perspectives. And some influence factors of carbon emissions have been proposed including the factors to increase carbon emissions, to reduce carbon emissions, which are regional and temporary factors, or long-term "robust" influence factors. Based on the theory of environmental economics, we employ the model of the extreme bounds analysis (EBA) and expand the Kaya identity; using the panel data of 30 provincial regions, and empirically analyzes the factors which have "robust" effects on per capita carbon emissions in provincial regions. And thus a general rule has been revealed between China’s regional environmental pollution and economic growth. That is, the six factors, local financial spending, industrial structure, energy efficiency, energy consumption structure, energy prices and passenger capacity, have anti-interference, robust, and significant impacts on per capita carbon emissions. Therefore, when developing economic, China should be fully aware of the impact of carbon emissions in order to achieve sustainable development. Based on these results, we propose some suggestions on which governments make policy of environmental protection and economic development. The policy implications of this study contain four aspects: 1) to adjust the industrial structure and limit the development of high-carbon industries; 2) to optimize energy consumption structure, to develop new energy, and to renewable energy; 3) to develop circular economy, to exploit clean technology, and to improve energy efficiency; and 4) to advocate a low carbon life, to promote low-carbon lifestyle. China is in the stage of acceleration of industrialization, urbanization, facing large-scale infrastructure construction, therefore energy demand of China shows a rapid growth. The driving factors of carbon emissions involves in economic development, industrial structure, energy consumption structure, and many other aspects, thus reducing carbon emissions will be a difficult, complex systems engineering. In the high-emission model of economic development, there exist a dilemma between emission reduction and economic development. How to explore the market laws of economic development and carbon emissions, establish associated carbon emissions market access mechanism and market transaction mechanism, this will provide a powerful impetus to low-carbon technologies and low-carbon economy. In the long term, this is conducive to promoting the sustainable development of China's economy.
The protection of arable land use plays an important role in the food security and it is of great importance to protect arable land resources. In the process of arable land use, driving forces that affect the changes in arable land area is rather complicated. With Qinzhou City as a case study, in order to provide a guidance for making reasonable policy in protecting arable land, this article is to research the driving forces from 2001 to 2010 that affect the arable land changes and reveal this mechanism, adopting the principle component analysis in terms of economy, population, agriculture and land. The study indicates that the arable land area in Qinzhou City decreases annually with an average of 460 ha. The main reasons are construction land use and disaster destroy as well as abandoned land. Economy and social developments as well as agriculture development that affect arable land changes in Qinzhou City are also the major driving forces of arable land changes. Meanwhile, economy and social development inevitably occupy a certain amount of arable land, but it is difficult to make up arable land with the same quality and quantity, which results in the decrease of arable land. The increasing population will boost the process of urbanization, where residences and infrastructures will occupy large amount of arable land. Agriculture that affects arable land changes mainly reflects on the industry adjustment, in which farmers readjust the agricultural structure automatically according to the benefits and it leads to the decreasing quality and quantity of a certain amount of arable land. Measures such as reducing construction land use and developing land use as well as raising land use efficiency can be taken to curb the trend of decreasing arable land in Qingzhou City. Effective plans such as land reclamation and using the used land as well as saving land use can be made to control land decreasing to protect arable land to a greater extent.
Because of its sensitivity, vulnerability, tourism is affected by meteorological disasters even more obvious.Currently, academic research on disasters warning information mainly concentrates on tourism disasters or meteorological disasters, but rarely on tourism meteorological disasters and warning system. Because distinguished from tourism disasters and meteorological disasters, tourism meteorological disasters have unique characteristics, therefore, to build tourism meteorological disasters is necessary.Huangshan Scenic Area is a famous tourist scenic spot at home and abroad, which features world natural heritage, cultural heritage and Geological Park. However, affected by the mountain climate, Huangshan Scenic Area is frequently stricken by tourism meteorological disasters, and geological disasters caused by this damaged the tourism resources and facilities, which influenced the tourism activities and even threaten the tourists personal and property safety. Therefore, based on the analysis of the impact of tourism meteorological disasters and combined with the characteristics of tourism meteorological disasters in Huangshan scenic area, this paper constructs tourism meteorological disasters prevention system. The system is mainly composed of tourism meteorological disaster monitoring system, early warning system and professional defense system. Monitoring system is to monitor temperature, relative humidity, visibility, atmospheric electric field, precipitation, lightning location information; Early warning system consists of lightning warning, storm warning, snow warning, flash floods and drought and low temperature warning; Professional defense system includes flash floods and geological disasters special defense, snow and icy roads special defense, droughts meteorological special defense, lightning special defense system.Taking lightning monitoring and early warning system as an example, the paper introduced the ideas of the construction, process of early warning and technology system in detail so as to provide scientific basis and reference for prevention of meteorological disasters in mountain tourism scenic spot.
Basing on statistical data over years, focusing on the relationship between economy urbanization and population urbanization, using softwares of EXCEL,SPSS and MAPGIS, this article makes a series of quantitative analyses on temporal and spatial series of population urbanization and economy urbanization of Dongting Lake Area since the 2001, in which the ratio of urban population to the total population serves as the index of population urbanization while the ratio of added value of secondary and tertiary industry to GDP is taken as the index of economy urbanization. As for contrastive analyses of time series, although urbanization of Dongting Lake Area has accelerated obviously since 2001, comparing with Hubei Province, Hunan Province and the whole China, economy urbanization of Dongting Lake Area still cannot drive population urbanization effectively. As a result, the lagging situation of population urbanization to economy urbanization of Dongting Lake Area has sharply aggravated since 2007. As for contrastive analyses of spatial series, both levels of economy urbanization and population urbanization of Dongting Lake area present concentric ribbon structures in which core region and peripheral region show a low level while marginal region reveals a high level. However, proceeding of population urbanization of marginal region is the fastest in Dongting Lake Area, and economy urbanization has being expanded from marginal region to core region. On the premise of ensuring food safety and ecological safety, for the sake of sound development of urbanization of Dongting Lake Area, eliminating resistances to population urbanization of Dongting Lake Area and increasing influence of economy urbanization on population urbanization are two key points. Besides, speeding assembling population and industries to marginal region is the crux of both promoting the interaction between population urbanization and economy urbanization, and increasing economic benefits of urbanization; Advancing the proceedings of agriculture industrialization and modernization of core region and peripheral region and promoting transformation of agricultural labor and transference of rural population are the keys to maintain social and ecological benefits of urbanization.
Barchan dunes are the most common and more in-depth researched aeolian landform, which have been learnt for a long time. This study briefly reviews the shapes and migration, formation conditions and process, flow field and erosion, grain size and structure, distribution and interaction of barchan dunes, and analyzes its study trends. Although a lot of important progress has been made in the study of barchan dune, there are still many problems needs to be solved. Firstly, shapes and migration are the most obvious characters of the barchan dune and have been researched since 1940. However, in the same region where the shapes of barchan dune are varied, the reasons are worth studying. Meanwhile, the researches in barchan dunes migration were concentrated on long period of time interval, while the short time interval studies, such as season and sand storm event, are critical in the projects of windbreak and sand-fixation, but have been concerned little. Secondly, in the formation condition and process, whether EST can stand for sand availability or not and which parameters can instead of it are still needed to answer. Meantime, experiments of the formation process are few, which are very important to prove the conceptual model. Thirdly, in the flow field of barchans dunes, how to measure shear force and the turbulent are very important aspects to study since how sand movement and deposition in the turbulent condition are the microscopic factors to explain the evolution. Moreover, studies of barchans dune structures are limited, so we can use new technologies, such as GPR(Ground Penetrating Radar) in the future. At last, distribution and interaction of barchan dunes are hot fields, where many studies have been done. However, they are still to be advanced and qualitative, and lots of problems are needed to solve. For instance, process, mass change and control condition of interaction, formation and development mechanism of barchans dune distribution.
This article presents an urban heat island retrieval and analysis method with HJ-1B satellite imagery. The study area is Beijing, one of the largest cities in the world, which has experienced a rapid urban expansion over the last two decades. Accelerated urbanization has created serious impacts on its thermal environment. Retrieval and quantitative analysis of UHI patterns in Beijing is significant to understand the worsening urban climate problem in the area. More than 200 HJ-1B images of the study area were acquired and analyzed. Then 48 least-clouded scenes were selected to generate LST maps. The digital number (DN) values of the HJ-1B TIR band were converted from their recorded DN to spectral radiance. In order to perform the extraction, temperature images are created by masking out all areas of clouds and open water. To eliminate atmospheric interference on HJ-1B images, atmospheric correction of the red and near infrared reflectance band of HJ-1 image was carried out using ENVI FLAASH atmospheric correction module. The wavelength of the TIR band of HJ-1B is similar to the thermal band of TM5, and the spectral response curves of the two TIR bands matched well. Because HJ-1B has only one suitable thermal band to retrieval LST, so we adopted single-channel algorithm to retrieve LST from TIR band of the HJ-1B satellite. Land surface emissivity (ε) can effectively transmit thermal energy across the surface into the atmosphere, which was obtained through the NDVI thresholds method. A 2.5-dimensional Gaussian surface approximation was modeled to quantitatively describe the location, shape and size of the heat island, and to describe the urban heat environment and its seasonal variation. The algorithmic procedure for UHI analysis was performed in IDL (Interactive Data Language). The input data of UHI extraction were the HJ-1B LST imagery, as described above. The average suburban LST plus a threshold value (1℃) were regarded as potential heat island pixels. It was found that the daytime UHI demonstrated distinctive seasonal variation, with the maximum during summer and the minimum during winter. A series of 2.5-D model were created to analyze the UHI and its seasonal variation. Through monitoring and analyzing the UHI effect, the results illustrated that the spread of the UHI in Beijing extended for 33.92 km in longitude direction, 40.92 km in latitude direction and 1 090.14 km2 in footprint area in summer, respectively. The urban area surface temperature was lower than the rural area temperature in winter, which has become an urban cooling island. On the basis of the accurately retrieval and analysis of Beijing UHI with HJ-1B satellite imagery, it was concluded that the HJ-1B TIR image is an ideal source for UHI study.
In order to explore the runoff change characteristics in and out of the Dongting Lake Basin, using the annual runoff time series data, time series analysis was performed for nine stream flow gauging stations located at the main rivers of three outlets and Four Rivers (Xiang River, Zi River, Yuan River and Li River) in the Dongting Lake. The concentration degree and concentration period, Mann-Kendall trend test method, variation coefficient method and the runoff anomaly percentage were performed to analysis the annual runoff series of the main control hydrological station in Dongting Lake Area. The results showed that: ① The runoff concentration period of Dongting Lake Area mainly concentrated in June-July of each year, and the maximum runoff time is the end of June and early July. The flood occurred mainly in mid to late July. Runoff period synthetic vector directions are ranged from 103.2° to 190.2°, which can reflect the maximum runoff of the rivers in and out of the lake. The concentration period was in consistent with the actual runoff during the year distribution statistics. ② There is great variation of yearly runoff, with variation coefficient ranging from 0.194 to 0.761. It tells that the runoff stability is poorer. The ratios of extreme values are all above 0.6, and river runoff attenuation is more obvious. ③ Judging from the alternation regularity of runoff, frequency of enormously wet and dry year of Four Rivers Basin is lower than that of normal hydrological year. Namely, the frequency of normal hydrological year is relatively low in Four Rivers Basin. Frequency of enormously wet and dry year of Ouchikou is relatively high, accounted for 32.79% and 57.38% respectively. The interannual variation of runoff is relatively severe, which is not conducive to the rational use of water resources. It also implies that Dongting Lake Area is more frequent to encounter drought and flood disasters. Above conclusions show that the flood of the Dongting Lake is the emergence of flood the three outlets and Four Rivers Basin. But the flood is also controlled by the flood from the upper and middle reaches of Changjiang River. The long-term trend changes of stream runoff are controlled by the variation of climate changes, and impact caused by human activities and water conservancy project construction.
The sediment core SC07 was collected in the subaqueous delta at the Changjiang River estuary. Radioisotopes of 239+240Pu and 137Cs were analyzed focusing on discussing the distribution characteristics of activity profile, then the difference between 239+240Pu and 137Cs profiles were obtained. Results displayed that, there were the same cumulative peaks of 1963 and 1958 both in 239+240Pu activity profile and in 137Cs profile. The 239+240Pu activity profile showed a good agreement with the 137Cs profile (R2=0.765), that is to say, they can convey the same information about sedimentation processes. The start layer of 239+240Pu activity was corresponding to 1948 while 137Cs was corresponding to 1954, which showed the more measurement sensitivity of 239+240Pu. 137Cs/239+240Pu activity ratio was quite different after moratorium on nuclear testing, which really did good to dating for the sediments. Moreover, the 137Cs/239+240Pu activity ratio played an important role in distinguishing nuclide source in the environment. Meanwhile, it has been seen that 137Cs/239+240Pu activity ratio of the sediments core was lower than the global average, indicating that 239+240Pu activity concentrations were partly from close-in fallout. 239+240Pu activity in the sediment core was between 0.072-0.716 mBq/g and 137Cs was between 0.390-16.210 mBq/g. 239+240Pu atmospheric fallout mainly concentrated in the 63-111 cm, while the 239+240Pu activity between 0-45 cm decreased obviously. There were one peak (71 cm) and two sub-peaks (63 cm and 99 cm) in the vertical profiles of 239+240Pu. It needs to be mentioned that the peak at 71 cm was corresponding to the year 1963. The cumulative sub-peak at 63 cm may be caused by China's nuclear test that happed during the 1970s-1980s. Also, the cumulative peak (73 cm) in the vertical profiles of 137Cs was corresponding to the year 1963, which was nearly the same with vertical profiles of 239+240Pu. Because of the extremely complicated dynamic action of Changjiang River estuary area, the existence of cumulative peak of 1986 the vertical profiles of 137Cs was still needs further research. In a word, it has been suggested that the radionuclide 137Cs, 239+240Pu and the activity ratio were useful tools in studying the material source, evolution of the delta, as well as the deposition rate.
HJ-CCD images being a data source, this paper calculated and analyzed the c change characteristics and spatial distribution about the vegetation in south Jiangxi regions in 2008-2011 by using the dimidiate pixel model based on NDVI, and DEM terrain elevation data were adopted to extract geomorphologic factors, and analyze the relationship between the elevation, slope, aspect and vegetation cover and vegetation degradation. The results show that it has a strong positive correlation between vegetation cover and elevation in the red soil region, the correlation coefficient is respectively 0.946 1 and 0.954 5 in 2008 and 2011.Vegetation degradation is mainly concentrated in the high vegetation coverage area, from the geomorphologic distribution of degradation area of view, it accounted for 88.84% of the total degraded area between 100 m and 300 m elevation range, 88.41% of the total degradation area between 1° and 5°slope range, the degradation area distribution from 306° to 360° slope range accounted for 30.73% of the total degradation area, it shows vegetation degradation is mainly concentrated in the region of low slope and low elevation, vegetation degradation is more serious in shady slop. From the geomorphologic distribution of vegetation degradation degree of view, the regions which the elevation range is from 50 m to 150 m, the slope is of less than 13° or more than 27° are the most violent regions of vegetation degradation, the degradation degree of shady slop is stronger than sunny slop. This study quantifies the relationship between vegetation cover and topography factors, provides a scientific basis for environmental management and monitoring in the red soil region, and has some practical value.
Landslide disaster restricts the sustainable development of human beings which would cause deaths and injuries, property damage and living environment ruins seriously. The regions should be divided into deferent types on the base of disaster risk when making macroeconomic policy of regional geological disaster. Thus, it is very necessary to make susceptibility assessment on zoning prone and risk of geological disasters in these regions firstly. When different assessment models are employed, the results are different. Furthermore, land types according to result of the susceptibility would results in difference in economy. Thus, it was more important to employ suitable model whose susceptibility assessment results were objective and realistic to the fact; however, there were few reports in this field in China yet. This study made assessments on the susceptibility of landslide disaster and evaluated the results. The employed susceptibility assessment models were information value, logistic regression and artificial neural network model. The relative relief, slope, aspect, river system, distance to fault, vegetation cover, formation lithology and road were chosen as factors. The results were showed as following. Firstly, the accuracy of classification influenced the social economic cost. Cohen’s Kappa factor method, precision evaluation method proposed by Sridevie Jadi and ROC curve method as the evaluation methods were used to evaluate the assessment results obtained from above models. The Kappa coefficients were 0.72, 0.69 and 0.55 by artificial neural network model, logistic regression method and information value model, respectively. The empirical probity (namely accuracy of prediction results) proposed by Sridevie Jadi of above 3 models was 87.48%, 74.26% and 69.54%, respectively. The AUC values were 0.805, 0.724 and 0.684, respectively. These evaluations proved that the assessment result obtained by artificial neural network model was more realistic to the fact. As a result, artificial neural network model performed the highest level of accuracy in the 3 models. Secondly, there could be one zone and 3 areas according to the landslide assessment results in Ningqiang County. They were: the zone of two sides of Mianxian County-Yang pingguan-Jin shanshi fault, volcanic area of Da′an-Miaoba-Gongjiahe-Daijiaba, shale, siltstone and slate area of Tiesuoguan-Hujiaba, phyllite, slate and sandstone area of Anlehe-Guangping, respectively. The area of high-susceptibility area was 1 300.85 km2 which accounted for 39.96% of the county area. Landslide in this area was well developed which was affected by Jinshansi-Yangpingguan-Mianxian fault obviously. The area of medium and low susceptibility was 1 227.34 km2 and 727.02 km2 which accounted for 37.7% and 22.33% respectively.
The cosmogenic exposure dating method that measures trace cosmogenic nuclide concentrations present in terrestrial surface rocks developed in the late 1980s. This method has become a widely used tool to address scientific questions in the fields of geomorphology, glaciology, palaeoclimatology, palaeoseismology, soil science, volcanology and geohazard research. Until now, three types of uncertainty affect the precision and accuracy of cosmogenic isotope dates; these include: analytical uncertainties including systematic errors, production rate uncertainties and sampling uncertainties. The cosmogenic nuclide concentration on the surface of rocks is a function of exposure time and erosion rate. However, it is usually hypothesized that the sample erosion rate is zero when dating the age using cosmogenic exposure dating method due to poorly constrained rock surface erosion rates. Recent research suggests that the assumption of “zero erosion” may underestimate true exposure age and the effect will increase with increasing sample age. In order to explore the impact of different erosion rates to the different exposure ages sample, we gathered 56 rock cosmogenic 10Be datum from different areas in the literature of 2009-2012. We analyzed the effects of zero erosion between 0.5, 1 and 2 mm/ka for the 1×104 a, 10×104 a and 50×104 a scale samples respectively. The erosion rates datum stem from mircro-weathering measurements and maximum erosion rates of the oldest sample using the cosmogenic exposure dating method in different areas. The results suggest, that the age for 1×104 a is underestimated approximately by 0.5%, 1% and 2% for erosion rates of 0.5, 1 and 2 mm/ka, respectively. For the age of 10×104 a, the underestimate is approximately should be 5%, 7% and 20%, and for 50×104 a approximately 40%, 70% and even more than 100%, respectively. The results are consistent with previous research results which suggest that our results are reliable. At the same time the result means that the erosion rates of surface rock significantly affect the accuracy of cosmogenic exposure dating method, and in particular for the older exposure age samples. Thus, future studies should pay attention to this issue.
Horqin Sandy Land is one of the key regions for desertification prevention and control in China. However, there is lack of exact boundary of Horqin Sandy Land at present. Subsequently, the control and recovery process of environment in this region is affected. Based on both the existing literatures and the formation history and earlier distribution of the Horqin Sandy Land, the core region of the area was first determined in the present study. Then, 26 intersections for the boundary of the core region from 16 directions were taken as the samples using the ecology sampling method. Remote sensing and GIS methods such as linear spectral mixing model and tasseled cap transformation were adopted to process the Landsat-5 TM images in the study area. Three components after tasseled cap transformation (i.e. brightness, greenness and wettness) were used to identify the sample points in the southern nine directions. Based on multiple replication tests, optimal thresholds were selected by obtaining the demarcation characteristics of each intersection sample and the exact boundary of Horqin Sandy Land was delineated accordingly. The linear spectral mixing model was applied in the northern directions because the sandy land and saline-alkali soil were distributed crossly. Combined with the optimal thresholds, the northern part boundary was delineated accordingly. However, this method was inapplicable to two directions and the thematic map of land use types was used to explore the demarcations. Subsequently, field investigation, high resolution images provided by Google Earth and the permanent geomorphology features were combined to confirm each direction of the final boundary of Horqin Sandy Land. According to the verification, the boundary was adjusted slightly. The results showed that the area of Horqin Sandy Land was 52 300 ± 360 km2 with the verification accuracy greater than 94%. The errors were caused mainly by the set of threshold values, precision of spectral unmixing results and the resolution of images. The achievements in the present provide the reference to eco-regionalization and environment monitor and ecological restoration in the definite confines in Horqin Sandy Land.
