With the acceleration of China's urbanization process, the improvement of urbanization level effects on various aspects of China's economy and society. This article focuses on urbanization level and spatial distribution of China's manufacturing industry. Based on statistical data of 2001-2011 and panel regression, it finds that the level of urbanization is an important factor affecting the spatial distribution of China's manufacturing industry, and they have an inversed U-shaped relationship. Using the share of the provinces and autonomous regions' manufacturing output accounting for the country's total manufacturing output to reflect the spatial distribution of China's manufacturing industry, it shows that when the level of urbanization is lower than 36.26%, the share of the manufacturing sector is getting larger along with the improvement of urbanization level. While when it is over 36.26%, the improvement of urbanization level will no longer push up the share of the manufacturing sector, but lead to its decline. Furthermore, labor-intensive, capital-intensive and technology-intensive manufacturing have certain differences in the spatial distribution, the degree of change and share, and the correlation between urbanization level and spatial distribution of manufacturing industry. The inflection points for labor-intensive and capital-intensive manufacturing are 26.91% and 29.16%, both lower than 48.54%, the inflection points for technology-intensive manufacturing. And it confirms the basic rule that labor-intensive and capital-intensive manufacturing industry transform and upgrade to technology-intensive manufacturing industry. In addition, labor wage is positively related to the spatial distribution of China's manufacturing industry. And transportation infrastructure level and location also have an impact on the spatial distribution of China's manufacturing industry.
Cities and towns have also been a rapid development as the organizational form of the advanced productive force, and gradually become the dominant force in the society and life. Urbanization has a profound impact on the change of community economy and the distribution and flow of population. This article analyzed the development conditions of the west provinces by the panel data from 2000 to 2010, and analyzed the relationship between urbanization, population and economy (GDP). It revealed the change and relationships of urbanization, economy and population of twelve provinces in West China during the periods of"Ten Five-Year Plan"and "Eleventh Five-Year Plan". The results showed that during 2000 to 2010, the 10-year average actual level of western region urbanization was 39.0%, far below the 10-year average actual level of national urbanization of 47.2%. The average annual GDP growth rate of the western region was 12.34%, higher than the national average growth rate of 10.48%. The country's contribution degrees of the increment of GDP of Sichuan, Inner Mongolia, Guangxi, Shaanxi, and Chongqing were higher than other province in west china. During "Eleventh Five-Year Plan", the highest level of urbanization was Inner Mongolia in western region, higher than the national average; the lowest level of urbanization was Tibet; after 2008, the urbanization level of Chongqing was higher than the national average, but those of other province in west China were below the national average. There was a positive correlation between the level of urbanization and regional economies. The economy was more active, the level of urbanization was higher. The population had a positive and negative influence correlation with the level of urbanization. Excluding of the GDP impact, there was the negatively correlation between population and urbanization of Chongqing, Sichuan, and Inner Mongolia. The level of economy and urbanization has been greatly improved in the twelve western provinces during periods of "Fifteen Five-Year Plan" and "Eleventh Five-Year Plan". China's macroeconomic policies have the guidance and macro-control functions on the level of urbanization.
There is some lacking of measurement of spatial market power and topological analysis in current academic researches. This article measured the spatial market power of China Everbright bank based on a commercial bank model, and gave the topology diagram according to the measured data. The change pattern can be deducted from three topology diagrams from 1999 to 2009. It is found that the topology of China Everbright bank is obeyed to poisson distribution according to the degree distribution testing. More interesting finding exists in the analog calculations of setting network order in eight un-operated provincial locations for China Everbright bank. The analog result keeps consistent mostly with the reality of market developments of China Everbright bank. The new path setting of eight provincial locations at a later stage follows the topology optimization process, though not intentionally. Our study method can give some reference to a corporation which has regional operation network in knowing its topology and rational use of its existing space advantages.
Tourism development quality is an important strategic issue of tourism development, and it is also the key to accelerate healthy and sustainable development of tourism industry in China. For a long time, tourism development quality level is not high due to one-sided pursuit of development speed and scale for tourism industry in China. It is urgent to study this scientific proposition in order to ensure the coordinated development between tourism quality and tourism quantity. Based on the connotation of tourism development quality, this article proposes that the evaluation index system of tourism development quality, which is composed of 5 categories of indexes (quality of tourism products, quality of tourism service, quality of tourism facilities, quality of tourism market and quality of tourism environment) and 31 detailed indexes. In order to measure the coordination between tourism development quality and quantity, this article also establishes the coordinated development degree model. According to provincial cross section data in 2010, the index of tourism development quality was calculated, and coordination of tourism development quality and quantity was measured, then each provincial tourism development situation was analyzed. The major conclusions of this article are as follows. Firstly, Chinese overall level of tourism development quality is rather low, and spatial difference is obvious. Provincial tourism development quality reduces from the Eastern China to Central China, and from Central China to Western China. The tourism quality of Chinese provinces can be divided into four types, which are high quality type, high-intermediate quality type, intermediate-low quality type and low quality type. Secondly, from the aspect of correlation between tourism development quality and other economic indicators, tourism economic development level could not reflect the quality of tourism development, and there is also no corresponding relationship between tourism economic scale and tourism development quality. One-sided pursuit of quantity indicators such as tourism development scale is not recommended. These tourism economic indicators should be downplayed in the future, and multi-dimensional indicators such as tourist satisfaction index, tourism environment quality index, level of convenience for people and the degree of standardization should be attached more importance. In addition, from the aspect of coordination between tourism quality and quantity, the overall level of Chinese tourism development coordination is on the low side. According to it, 31 provinces in China can be divided into four types, which are good coordination, moderate coordination, reluctant coordination and maladjustment. Finally, this article focused on the tourism development speed. The result shows that tourism development speeds in good coordinate development provinces are commonly at low level. Based on locally weighted regression and smoothly scatterplots, this article finds that tourism development speed presents a significant pullback trend on the whole with the improvement of coordinated development degree, and the possible factors of the pullback trend are discussed.
Central China, which consists of Shanxi, Henan, Anhui, Jiangxi, Hubei and Hunan provinces, is an important base for main food supply in China. After analyzing scale advantage, efficiency advantage, comprehensive comparative advantage and concentration ratio of grain production in Central China, this article further discusses countermeasures for the construction of grain production base in this region. First, it is found that, since 1978, rice and wheat in Central China have a stable comprative advantage while the corn and soybean do not. The comparative advantage index of rice production is above 1.10 per year and wheat production shows a steady rise, going from 1.00 in 1978 to 1.16 in 2012. The comparative advantage index of corn production is below 0.80 and soybean production presents a downward trend, going from 0.90 in 1978 to 0.80 in 2012. Second, seen from the horizontal perspective, the structure of comparative advantage of the four grain crops changes slightly. In 1978, the sequence of scale advantage is rice, soybean, wheat and corn, the sequence of efficiency advantage wheat, rice, corn and soybean, and the sequence of comparative advantage rice, wheat, soybean and corn. In 2012, the sequence of scale advantage is rice, wheat, soybean and corn, the sequence of efficiency advantage wheat, rice, soybean and corn, and the sequence of comparative advantage wheat, rice, soybean and corn. Third, the concentration ratios of grain production in eastern, western and northeast regions of China fluctuate whereas the concentration ratios of grain production in the central region keeps rising steadily. The concentration ratio of grain, rice, wheat and corn rose from 28.65%, 38.13%, 28.83% and 16.16% in 1978 to 30.08%, 39.87%, 42.40% and 17.16% in 2012 respectively. The statistics in 2012 shows that the concentration ratio of grain, rice, wheat ranked first among the four regions. Fourth, the analysis shows that grain production in the central region plays an increasing role in China. Therefore, from the perspective of grain safety in China, importance should be attached to grain production in Central China so as to remain firm in the status of the central region as a base for main food supply. And various measures should be taken to promote the stability and growth of grain production in Central China.
The relation between the service space and urban function space is one of the important study topics in geography. Based on the land utilization data of 1995, 2003, 2008, the remote sensing images of Changchun City in 2011 and related statistical yearbooks, combination of GIS and SPSS statistical tools, this article discussed the relations between service space and urban function space during the transition period of Changchun. The results show that: 1) The gravity center of service plot presented volatile clearly, which was located in the southeast from 1995 to 2003, whereas it was located in the northeast during 2003-2008 and in the southwest during 2008-2011. Its extend mode was given priority to quick push outward, while the internal filling was complementary. 2) The service space presented overall diffusion, local concentration, and the expansion intensity was increasing. Suburbanization had appeared by it. On the basis of the previous research, this article attentively analyzed the diversity change characteristics of service plot and its extension mode in different stages, the conclusions demonstrated that: a. the service land parcel changes others distinctly from 2008 to 2011; b. it extended exteriorly in 1995-2003, and simultaneously expanded externally and filled internally in 2003-2008; c. it had layers of distribution and the gradient of the nature in 2008-2011. 3) The service space and industry space Changchun have no coordination. The industry space expansion of Changchun guided the service space expansion on the outer extension of urban function, while the industry space integrated the service space on the inner inversion of urban function. The service space and living space belonged to mixing state as a whole, but the stripping trend had highlighted. Obviously the single center structure of service space had been shown a delay trend to the traffic space expanding outside. 4) The natural environment, economic development level, government plant policy, urban planning and traffic factors jointly impact on the spatio-temporal different characteristics formation of the service space and urban function space in Changchun City.
As an important property of city, city functions in different periods differ in forms, intensity and spatial characteristics from the preindustrial age to the postindustrial age. City function experienced from a single and simple function to various, messy and homogeneous functions and then to the diversified different and complementary networked evolution process. This article tries to open a new view angle of city linkage research based on the evolution of city function by constructing an analytical structure of city functional network. The city functional network in the postindustrial period consists of three components of function elements, linkage channel and role carrier. On the basis of diverse, different and complementary city function and through the tangible or intangible linkage channel and taking the entity or virtual spatial flow as the role carrier, forms spatial network structure of city functional network was formed. Based on the evolution process of city function and the concept and connotation of city function network, the article took the evolution of city function network in the Zhujiang River Delta as an example, and reconstructed the history and space features of city linkage in the region and finally constructed a new analytical perspective of city function network on city linkage researches.
Urban spatial morphology evolution can reflect the regional urbanization in the concise and effective way. It comes into effect to achieve the regularity of spatial morphology evolution by identifying landscape change characteristics dynamically with landscape expansion index. In accordance with current problem in landscape expansion index calculation, this article proposes a method that analyzes the characteristics of urban spatial form change by improved calculating landscape expansion index. Firstly, 3 topological relationships (contain, intersect and not-touch) are applied to representing 3 landscape growth pattern which are infill, edge-expansion and outlying accordingly. Secondly, by judging the new patches of urban topological relationship, each landscape expansion index is calculated depending on the definition. And then based on the results of calculation, this article analyzed the morphology of urban spatial pattern evolution in Suzhou-Wuxi-Changzhou (SXC) region in each period during 1985-2008. From the aspect of the total trend of landscape expansion pattern in SXC region, the edge-expansion was the leading expansion trend which was belong to compact growth. Seen from the other aspect, there were differences in the location of the urban morphological growth. In the urban district or the administration center of each town, the morphological growth could be summarized as compact growth in edge-expansion way. And both of the urban sprawl or the compact growth could be found in the rest of the area. The results illustrated that by using the method of the landscape expansion index the morphology of spatial pattern evolution can be analyzed dynamically. Furthermore, box-counting dimension, as one of the most popular fractal methods, was applied to calculating the urban fractal dimension. The results shown that box-counting dimension of the urban in SXC region increased through the years. During 1985 to 2008 the dimension value is range from 1.22 to 1.504 in the low growth rate which means that the spatial morphology of urban was always between the concentration status and the equilibrium status. On the other hand, the results of landscape expansion index showed that patches of outlying pattern increased from 1995 which gave some disturbances to the leading compact growth pattern. This spread pattern caused spatial heterogeneity among the urban and towns. The growth poles of the new construction land brought about the change to the space structure. Urban expansion in outlying pattern would enhance the randomness of spatial morphology and instability to the spatial structure. These results could explain the result of box-counting which fractal method could not explain well. Therefore, landscape expansion index can provide spatial process interpretation for fractal dimension which is the result of spatial morphology as supplementary. Furthermore, the decision maker can comprehend the trend of spatial morphology evolution during the urban expansion by calculating landscape expansion index so that urban sprawl can be controlled by macro policy in the reasonable way.
The combustion of fossil fuels, followed by changes in land use, is an important source of carbon dioxide production. More than 80% of carbon emissions come from urban areas, but studies often ignore the relationship between human settlement, the environment and the carbon cycle. Not sufficient attention was devoted to studying the role of urban systems in global climate change and in the carbon cycle, particularly carbon- accounting inventory at the city level. This study explores the land use change that led to changes in carbon emission intensity in Harbin City from 2004 to 2012. It used land use and energy consumption data to better understand the effects of carbon emissions in Harbin. In this article, we measured the major land use types and carbon emissions (and absorptions) for the 9 years, and then gave an analysis of the situation of the carbon emission per unit, and discussed the effects of different land use change on carbon emissions. Finally, we estimated carbon emission for the year of 2020, providing references on low-carbon development in Harbin. The results showed that: 1) carbon emission was 361.451×104t in 2004, and reached 1875.658×104t in 2011; 2) construction was the main type carbon emission area, accounting for 96.987% of the total annual carbon emission; woodland was major carbon sink areas, accounting 99.907% of the carbon sinks, and the total absorption was about 1523.030×104 t of carbon per year; 3) the carbon emission intensity in Harbin increased from 0.681 t/hm2 in 2004 to 3.534 t/hm2 in 2012; 4) land use for construction showed a rapid growth in carbon emission before the year of 2008, and after that showed a slow and uneven growth; 5) the estimated carbon emission in 2020 will be 3558.264×104 t for construction land; while the total carbon emissions will be 2055.839×104, compared to the year of 2012 will increase 180.181 ×104 t, with an annual average growth rate of 1.153%. With continued urbanization and industrialization, carbon emission shows an increasing trend in Harbin, and it has a definite impact on the ecological environment. We suggest the following for controlling carbon emission. First is to improve the carbon heating situation in winter. Harbin has a long and cold winter, with a heating period up to six months. The heating energy structure is still dominated by coal, and the use of clean fuels is much lower. Worse, industrial development and heating using coal are increasing, so to optimize energy supply and improve energy efficiency, and Harbin should strengthen development and use of low-carbon technologies. Second is to develop a‘carbon sinks'model in Harbin to look for a suitable mode of forest resource management, and constantly to enrich Harbin's carbon sink economic resources. Last is to promote the idea of establish a low-carbon life-style.
Settlements are places of habitation, production and the living places for people. This article selected Korqin Left Wing Middle Banner as the study area, which was a typical farming-pastoral ecotone in the northern China. We selected elevation, slope, and aspect as factors that affected the distribution of rural settlements, and these factors were divided into 9, 6 and 8 grades, respectively. We conducted research about the distribution of rural settlements on different elevation, slope, aspect, and analyzed the impacts of rural settlements on land use pattern in ecotone between agriculture and animal husbandry. The results showed that: 1) Rural settlements mainly distributed in the areas that is from 0 m to 200 m above sea level, or where the slope is less than 6°, or shady slope. These are because the higher the altitude, the poorer living conditions are, which make it is difficult to build house and road. Moreover, the elevation also affects the precipitation and temperature that are critical for farming and grazing. Generally speaking, slope is a very impotent factor influencing the distribution of rural settlements. However, due to the study area is flat, we cannot find an obviously change trend of settlements density on different slope gradients. Affected by freeze-thaw action, settlements density on the shady slope is greater than that on the sunny slope. 2) Rural residential has a direct impact on land use pattern, the greater the rural settlement density, the greater proportion of agriculture land and the less proportion of grassland, and vice versa. The total area of cultivated land that located within 2 000 m away from the settlements is 2 701.90 km2, representing 74.4% of the total arable land; the grassland mainly distributed in the areas that farther away more than 1 500 m, The total grassland that within 1 500 m from the settlements only 35.1% of the total grassland, about 1 391.83 km2. In addition, according to the proportion of arable land and grassland within each town, the study area can be divided into agricultural region (cultivated land proportion > 50%), pastoral region (grassland proportion > 50%), agricultural and pastoral region (cultivated land proportion < 50% and grassland proportion < 50%). In agricultural region and pastoral region, the distribution of farmland and grassland around residential areas followed the same pattern: the farther away from the settlements, the less proportion of cultivated land and the higher proportion of the grassland. However, the situation is the opposite in pastoral region: the farther away from the settlements, the higher proportion of cultivated land, and the proportion of grassland away from residential areas within 2.5 km remain unchanged on the whole.
Waterlogging is a common natural disaster which may delay sowing time of crops. The identification of the waterlogging before sowing crop is conducive for constructing prevention facilities and reducing losses. Land surface soil moisture is the most direct data for monitoring farmland waterlogging. Soil moisture product from satellite remote sensing data with near real-time and large coverage characteristics is very suitable for detecting soil moisture variation regionally. In this article, the 1978-2010 microwave remote sensing merged soil moisture product developed by Europe Space Agency, the SMOS MIRAS 2013 L3 10-day soil moisture product and monthly precipitation data from meteorological stations are used to discriminate the extent and severity of spring waterlogging in Northeast China based on Soil Moisture Departure Index (SMDI) and Soil Moisture Anomaly Index (SMA). Take the mean soil moisture of 30-year as the reference value, the soil moisture in late April, early May and mid May of 2013 is compared with the reference value of soil moisture, and the waterlogging event can be inferred by the fixed domain value. After the extent and severity of waterlogging are identified, we analyze the relationship between the waterlogging event and monthly precipitation, also the relationship of the severity of waterlogging of one place with its elevation. Through these analysis, some results are summarized as below: 1) Heilongjiang Province in Northeast China has the largest area affected by the 2013 waterlogging event and the waterlogging affected area is about approximately 110 000 km2, accounting for about a quarter of its total area; 2) Comparing monthly precipitation data with the degree of waterlogging, it is found that heavy rainfall (including snow) in winter and spring is the main reason for spring-waterlogging; 3) The severity of the spring waterlogging negatively correlates with elevation, and the waterlogging area are distributed below the 500 m elevation.
A soil water characteristic curve (SWCC) defines the relationship between soil water potential and soil water moisture. SWCC is one of the main tools used to model soil water and solute transport. Soil water characteristic curves were directly affected by different soil physical and chemical properties in saline-sodic soil. In this experiment soil water characteristics were studied for the two soil types (saline meadow soil and alkaline- sodic soil). Soil water potentials were simulated and soil water characteristic curves were drawn by Levenberg- Marquardt and global optimization calculating method. The results showed that change on soil moisture of saline meadow soil is obvious under different water potential, soil moisture in 0-40 cm soil layer is significantly higher in saline meadow soil than alkaline-sodic soil under the same soil water potential. For saline meadow soil, the total porosity was bigger than 50%,porosity of macro capillary (equivalent pore: 0.1-0.1 mm) can exceed 70% of total porosity. Total porosity was lower in alkaline-sodic soil, which hold the highest amount of micro pores (equivalent pore:＜0.1mm). Soil water-holding ability seriously low for alkaline-sodic soil. The modeling results showed a good agreement with the observed data, and captured the generally trend of the observed data. The calculated correlation between the simulated and observed data was above 0.9, decision coefficients were over 0.86, indicating the good match between modeled and observed results. The results from this research can provide basic parameters for soil water and salt movement simulation in saline-sodic soil area.
With the deepening of the disaster research worldwide as well as China's rapid economic development in the past three decades, people both within China and around the world have paid more and more attention to the awareness of disaster prevention and reduction. The risk assessment is one of the most important and basic study areas and has thus become increasingly important and urgent for China. The risk assessment is not only for the risk analysis, which has become an important part of disaster prediction, damage assessment, and disaster reduction decision. The risk assessment has also a great significance for the disaster risk during the development, utilization of resources, disaster defense, and governance and reducing disaster plan. In addition, this type of assessment could provide the scientific basis for the rapid assessment and decision making when suffering disasters. Flood is one of the most devastating events among the disasters. It is well-acknowledged that flood risk assessment is the first step in the management of flood risk. As a kind of non-engineering flood control measures, this type of assessment aims to obtain the flood disaster status both timely and accurately. In order to reduce the harm caused by the rainstorm flood disaster as much as possible, and to understand the occurrence and development of the rainstorm flood disaster from the scientific sense, the assessments of regional flood risk has become one of the hottest issues in the current academic research. Firstly, this article elaborated the basic concept of the rainstorm flood disaster. Second, we investigated the current literature status both domestically and internationally on three aspects including the formation mechanism of flood risk assessment, risk assessment and regionalization of flood, and flood risk assessment method. We further pointed out the existing research problems on the establishment of the evaluation index system, the determination of the weight of the assessment index system, the evaluation method and model, and the driving mechanism of risk change. Finally, this paper carried on the predictions on the development trend of flood risk assessment from several aspects including the data processing, the temporal and spatial dimensions, and the method of risk evaluation. We believe that this study could become one of the most important handy references to help researchers and it may guide future studies in the investigation of flood risk assessment.
Based on the daily real-time, historical observation data and NCEP/NCAR reanalysis data, the characteristics of abnormal precipitation event and possible mechanism in South China during April 2012 were analyzed by the climatic statistics and climate event diagnostic methods. Results showed that the cumulative precipitation amounts were observed evidently more than normal in most South China during April 2012, with the regional averaged precipitation amount ranking as the maximum value for the same period since the year of 2001. Moreover, the abnormal precipitation event caused rainstorm and flooding disasters in parts of South China. Taking above precipitation event as a case study from monthly time scale, key factors affecting the variation of precipitation in the pre-summer flood season of South China were explored. The author analyzed systematically the possible formation mechanism for the abnormal precipitation event in South China from the perspective of atmospheric circulation system anomaly and moisture transport. The major findings are as follows: Firstly, The abnormal rainfall over South China during April 2012 was a direct result of contemporary atmospheric circulation anomalies. The favorable atmospheric circulation pattern with positive anomaly of geopotential height over the Ural mountain area and negative anomaly of geopotential height over most China and Mongolia, meanwhile, the South China Sea and northwest Pacific region controlled by abnormal anticyclonic circulation in the lower troposphere, benefited the cold air moving to South China and converging with the southly warm-wet air on South China. Thus the coordinated atmospheric circulation anomalies in higher latitude and lower latitude area provided favorable circulation backgrounds for the occurrence of abnormal precipitation event during April 2012. Meanwhile, most of South China was controlled by the atmospheric upward motions over the study period, with concomitantly divergence in upper-troposphere and convergence in lower- troposphere, thus vertical circulation system gave rise to the anomaly of precipitation in South China. Moreover, the stronger southwestly moisture was transported from Bay of Bangal, the West Pacific and South China Sea to South China, which was the center of convergence of moisture flux transport during April 2012, especially in the central and eastern parts of South China. The abnormal southwestly water vapor transporting from ocean to South China provided material conditions for the occurrence of abnormal precipitation event. All above mentioned have caused the abnormal precipitation event in South China during April 2012．
To understand the main controlling factors of the soil salinity in the Huanghe River Delta, multi-layer soil samples, phreatic water samples and typical vadose column were collected in this study. Spatial distributions of the content of Cl- were analyzed by using traditional statistics and geostatistical method. Results show that: 1) ranges of the content of Cl- at the soil depths of 0-20 cm, 30-50 cm and 50-100 cm were 0.08-35.23, 0.04-15.22 and 0.07-11.67 g/kg, respectively. Random variations at these three soil depths were 50.0%, 24.0% and 60.4% respectively. The content of Cl- at 30-50 cm depth was mainly affected by structural factors or non-human factors (e.g., vegetation, climate and topography). The content of Cl- at other soil depths was influenced by both random factors (e.g., management practices) and structural factors. The spatial pattern of the content of Cl- at each soil depth showed a substantial plaque-strip-plaque shape, which indicates the continuity and direction to some extent. It is also noted that the content of Cl- in soils positively correlated with that in phreatic water. 2) the groundwater level (0.50-2.50 m) was relatively shallow in the study area, while the groundwater level was generally less than 1.0 m in the coastal inshore. Due to the fact that the embedded depth of the groundwater did not change much, the spatial variation of groundwater level was significantly weaker than that of the content of Cl- in phreatic water. In that case, with respect to the key factor of the content of Clin phreatic water, difference of soil salinity caused by embedded depth of groundwater can be ignored to some extent. Under the condition of little changes in groundwater depth, similar the lithology and structure of the vadose zone, and roughly similar phreatic aquifer permeability, water in the phreatic zone was easy to transport to the vadose zone due to the plant transpiration and the water potential gradient in the unsaturated zone. Therefore, the pattern of the content of Cl- in phreatic water driven was similar to that of Cl- in soils; and 3) the average value of the content of Cl- in surface soils was smallest for the higher fluvial highlands (0.09) and flood land highlands (0.26 g/kg). However, the average value of the content of Cl- in surface soils was as high as 4.34 g/kg for coastal lowland. Through the redistribution of water, gas and heat, Topography controlled the direction of the migration of Cl- in the unsaturated zone and enrichment region. As a result, the content of Cl- in soils varied with the topography. Hydro-geology condition was the internal factor that determines salt migration and enrichment between the groundwater and the vadose zone. In addition, topography was the external factor that plays a key role of controlling in the Huanghe River Delta.
Taking Chaoyang City, Liaoning Province as the study area, with RS and GIS, based on RUSLE model, utilizing a series of data such as digital elevation model (DEM), rainfall, soil and RS images, the research of characteristics of spatial-temporal differentiation of soil erosion of Chaoyang City from 2001 to 2010 is conducted. Through the analysis of the time change of soil erosion modulus, time change of soil erosion intensity and spatial distribution of soil erosion intensity, the results of this research are summed up as follows: 1) The value of soil erosion modulus of this study area was generally in decline in 10 years. From 2004 to 2009 years, the overall situation was relatively good. Among them the average lowest value (254.02 t·km-2 ·a-1) was in 2009 due to the drought, however the average highest value (576.74 t·km-2 ·a-1) was in 2010 on account of torrential rain. And this is a special phenomenon, in contrast to the variety trend. 2) The area which is slightly eroded is rising. However, these indexes bounced back in 2010. From the spatial distribution of soil erosion, soil erosion modulus is on the high side place in the mountains. 3) Chaoyang County in north-west of the study area, is the most heavily eroded region. The average value of soil erosion modulus in that county (747.33 t·km-2 ·a-1) ranks the first. Besides, according to the standard, the rates of area which is intensively eroded or more serious are respectively 29.2%, 32.67%, 34.57% and 31.41%. In Lingyuan City, the rates of area which is intensively eroded or more serious are respectively 21.22%, 23.32%, 24.98%, and 29.04%. Similarly, soil erosion intensity in 2010 showed different degree of rebound in the study area. These above findings show that although 10-year period corresponding measures on soil and water conservation were taken in Chaoyang City, but there are still some areas (especially in Chaoyang County) for the prevention of soil erosion have not given adequate attention, especially in natural disaster prevention, and water and soil conservation measures may not be implemented. Protection of valuable land resources in the study area is still long way to go, it need to assess the situation of local governments at all levels to take various measures so as to prevent the occurrence of soil erosion.
In order to measure the contents of Cadmium (Cd), 98 topsoil samples were collected from the same points of the Zhujiang River Delta in the years of 2001 and 2007, respectively. Based on 98 soil samples, the spatial and temporal distribution of soil Cadmium concentrations was explored, in which risk management strategies were discussed. The results showed that the extent of soil Cadmium was highly enriched, the mean concentrations of soil Cadmium in the two periods was 0.28 mg/kg, which was 5 times more than its soil background values of Guangdong Province (0.06 mg/kg); Both mean values for multiple comparisons showed that the Cadmium mean change reached a significant level. The coefficients of variation of soil Cadmium were 0.83 and 0.72, respectively, which indicated that the Cadmium sources were mainly from anthropogenic activity. Based on the model of Soil heavy metal accumulation rate of two periods,the annual regional soil Cadmium accumulation rates from 2001 to 2007 were 0.016 mg/kg, while from 2007 to 2012 the average annual regional soil Cadmium accumulation rate was 0.014 mg/kg. The temporal and spatial distribution trend of soil Cadmium is predicted, using two models, namely time-space mode and space-time mode. In the case of less time-series data, time-space mode is more robust predictions. Soil in most of area will be contaminated by Cadmium in 2020. Therefore, there are three strategies in future risk management: 1) to take preventive strategies in non-polluting area; 2) to take control strategies in the contaminated area; 3) to take repair strategies in heavily polluted area.
The North Branch, separated by the Chongming Island, was once the main channel in the estuary of the Changjiang River. The human reclamation and the south migration of the main channel led to the narrowing and shallowing of the North Branch. Yuantuojiao Point is the intersecting point of the North Branch of the Changjiang River with the South Yellow Sea coastal line. The specific geographic location and the complexity of regional morphological dynamics developed a typical silt-mud tidal flat. Heavy metals contents of the tidal- flat sediments recorded rich information of the coastal environmental changes near the Yuantuojiao Point. In this study, the heavy metals sources and pollution evolution were discussed according to the heavy metals contents within the tidal-flat sediments at the Yuantuojiao Point. A drilling core of 218 cm was collected on the salt marsh at the Yuantuojiao Point. The grain size and 7 heavy metals (Co, Cr, Cu, Mn, Ni, V, Zn) of the YY core were measured. The chronology of this core was built by using the 137Cs dating. The correlation analysis, enrichment coefficient, human contribution rate, geo-accumulation index, and potential ecological risk coefficient of the heavy metals from the YY core were calculated. The results show the contents of heavy metals were lower after 1960, but were higher before 1960. The average content of V was significantly higher than the background and the content of Co is higher than the background for more than 100%. The average content of 7 heavy metals was most obviously higher than the background value at the depths of 132 cm of the YY core. The content of 7 heavy metals had a good relationship with grain size, indicating of the obvious"grain size control effect", and the heavy metals might have more coherent sources. The human contribution rates of 7 heavy metals from the sediments further proved that Cr was completely influenced by natural sources, the other 6 heavy metals contents were co-affected by the natural and artificial sources, but the natural source was still the main one. According to the environmental quality standard, the sediments are of no pollution for most heavy metals, but the sediments of the depths of 132 cm in the YY core were of free to moderate pollution for Co, Cu, V and Zn. The potential ecological risk level of 7 heavy metals was mild. However, the potential ecological risk coefficient and geo-accumulation index was higher before 1960 than that of after 1960. It is worthy to note that geo-accumulation index and potential ecological risk coefficient of 5 heavy metals (Co, Cr, Mn, V, and Zn) of the YY core show an increasing tendency after 1997. The accelerated accumulation of heavy metals at the Yuantuojiao Point should be paid attention. And the emission of heavy metals with larger toxicity coefficient should be reduced.
