This paper introduces the background and outlines of the theory of dualnuclei structure model and explains the connotation and three important preconditions for establishing this model. In the dualnuclei structure model, the strength of economy in central cities of a region must be most prosperous in this region, and the central city should have the same economic strength and scale as the seaport，and the two cities （the central city and the seaport）should have close social and economic relationship within the region. Recently, the model of dualnuclei structure of Wuhan and Shanghai was put forward and this paper deals with a conclusion by investigating in Shanghai that it is impossible for the two cities,Wuhan and Shanghai,to form dualnuclei structure at present according to the three preconditions of the model of dualnuclei structure. There are three reasons. Firstly, as a central city, Wuhan has little economic influence on Shanghai. Secondly, there is a definite difference in economic strength and city's scale between Wuhan and Shanghai. And the most important reason is that Wuhan has not built up close social and economical relationship with Shanghai and there is no functional supplement between The authors point out that it is necessary that the economical relationship of Wuhan and Shanghai should be strengthened, and we have to examing further in this field in order to form the model of dualnuclei structure of Wuhan and Shanghai. It is suggested that the economical cooperation of the two cities can be urged by technology diffusion. Then Wuhan and Shanghai can get further development and the dualnuclei structure model of the two cities can be formed and developed gradually by regional cooperation.

The ecological footprint (EF) conception has gained much attention over the last a few years. But no research has carried out with respect to calculations of EF time series in China. The theory of ecological footprint was introduced in this paper and applied to Jiangusu Province as a case study. The EF for Jiangsu Province during the period from 1990 to 2003 was calculated. The results showed that the per capital deficit of EF and total EF in Jiangsu Province was distinctive and tended to increase from time to time. At the same time sustainability in Jiangsu Province was dropped in the period of ten years. The reasons causing ecological deficit in Jiangsu Province was analyzed.

The Taihu Watershed belongs to the eastcoastal developed area in China. In 2000 the level of urbanization was 66.17%, near twice of the average urbanization level in China. Since the opendoor policy the region has been proceeding with rapid industrialization, from the countryside industry develop to the foreign investment industry. The affluent job opportunities in these new factories have attracted a huge immigratory population from all over the country. Hence immigration becomes an important element affecting regional development plan. With the data provided by the fifth population census this paper analyzed the regional composition and urbanrural composition of immigration, calculated the number of immigra tion and its distribution by cities (counties) in the Taihu Watershed. The immigration contributed to around two percent of the level of urbanization due to its unbalanced distribution between the rural and urban areas. For the total city population, immigration occupied about 18% on average. The proportion of immigration was significantly linearly correlated with city population size in cities with over 500 000 population, and the proportion was significantly correlated with GDP in cities with less 500 000 population. The results should be useful for the prediction of urban population size of the cities and for the prediction of regional urbanization level in the Taihu Watershed, and could provide references for other cities or regions with the similar social and economic situation.

In the period of 1990~2000, urbanization grew faster in the eastern and southern provinces and rather slower in the western and northern provinces in China according to Census data in 1990 and 2000. Thus the regional disparity of urbanization among provinces has transformed from the former NorthernSouthern pattern to the current EasternWestern. The regional disparities of urbanization in China is comprehensively caused by the different natural and environmental background, population growth, economic development among the provinces and the regional development policies of the central government. Among of those, the regional disparities of economic development and the promotion efficacies to urbanization growth are of critical importance. Further, a factor analysis between the urbanization levels and their 12 selected natural and economic statistical indices is conducted at the provincial level in 1990 and 2000. The results show that, firstly, the urbanization level of a province is positively related with its industrialization level or economic development level and negatively with its population density and per capita agricultural output while the impact of the former factor is more intensive and significant; secondly, with the proceeding of industrialization and economic development, the promotion effect of industrialization on urbanization growth become weaker and that of comprehensive economic development become much stronger.

Since early 1990's, the economic development in the Yangtze River Delta region has been in a very high speed. Recently, with the speedup of economic unification a new upsurge in economic development has emerged in this region, which will bring strong impact on its land resources, particularly on cultivated land resources. Facing this new situation and from the point view of land administration, some tactics to meet this situation must be adopted. In detail, under the prerequisite of making a better relation between economic development and protection of land resources, the services in supplying land resources for industrialization and urbanization as well as improving people's living condition should be more actively and initiatively enhanced. At the same time, the ideas to protect land resources, especially cultivated land resources should be more firmly and strongly kept in mind. In addition, the relation between the creation of the low valley for commercial costs and the preventon against losing of stateowned landed properties should be properly treated. Moreover, the land market should be more formally managed. Furthermore, the system of land inviting bids and auction has also to be improved, and the innovated way of land storage for future use should be more actively explored. Finally, more attention should be paid on the livelihood safeguard for the farmers who has lost or will lose all or part of their farmland in the course of land condemnation.

According to the fractal theory, the appropriate methods are used to compute the fractal dimensions of bankline and spatial distribution of island with aid of GIS and RS in five different years i e,1969,1985,1994,1997 and 2002. The parameters to compute the fractal dimensions used in this study include grid and areaperimeter. The software used in the study mainly includes Arc/Info, ArcView andSPLUS. According to the result and analysis, some meaningful conclusions are drawn as follows:First, there exits fractal characteristics, and the change of fractal dimensions shows the stability degree of banklines of the Yangtze River and islands located in the Yangtze River; Second, there exits some correlation between the fractal dimension and the number of islands. But the quantitative relation determined because of nonenough samples.Third, the length of bankline of the Yangtze River is not certain.Fourth, some things about bankline, including development and management of bankline and bracer engineering of the Yangtze River bank impact the stability degree of banklines to a some extent.

Based on the condition of ecological environmental survey in Anhui Province, the status of natural resources is analysed with the countermeasure proposed for the rational utilization. Cultivated land is the main type of land use, the main problem of safe utilization is the decreasing quantity and quality of cultivated land. The way to resolve the problem is to realize the equilibrium of overall cultivated land. The problem of forest resource is that the age structure of stand group, the variety of forest and trees are unreasonable，the function of ecoservice is low，the accumulation amount is not rich，the forest productivity is low. The measure of perfecting forest ecosystem and realizing forest ecosafety is to adjust forest structure, raise planting index . The water resource is not welldistributed in region,inefficiently used and partly polluted. The problem of water ecosafety can be resolved by implementing the project of diversion water of the Changjiang River to Huaihe Drainage Basin，improving water conservancy facilities，enhancing the efficiency of exploiting water and the capacity of dispose of sewage.

By using land use/cover change(LUCC) detailed survey data, the authors analyzed comprehensively the course of LUCC in Hengyang City during the period from 1994 to 2001. The spatialtemporal features of LUCC in the past seven years were revealed . The findings are as following: (1) Since 1994, the total amount of cultivated land and unused land reduced, but the others increased in various degrees. In general, agricultural land and unused land were transformed into constructed land while cultivated land was used as garden plot and water area and unused land became woodland. (2) There were obvious differences in LUCC before and after 1997. Great changes occurred before 1997 but much fewer after 1997. There were also some differences in LUCC among different counties of Hengyang City. The greatest change was observed in Qidong County and Downtown, and the smallest change in Hengnan County and Nanyue District. (3) The main reasons, influencing the distinct temporal and spatial differences were population increase, policy control and economy driving. It is mainly the policy factor which causes the temporal difference of land change of Hengyang City before and after 1997, and it is the terrain and relief factor and economic factor that cause the spatial difference of land use and land change in Hengyang City.

Through the multiple variable regression analysis, it was found that there was a linear correlation (r=0.93 ) between mean population densities and various land use indexes for 151 cities and counties, with population densities less than 1 000 person per square kilometers, in Sichuan Province and a logarithmic correlation of r=0.96 between them. Based on the established quantitative population density - land use model, the spatialization of population census data in Sichuan in 1999 was carried out. And actual township's population data in Luojiang County was used to verify the precision of spatialization. The result showed that the correlation ratio between actual township's total population and the total population calculated by spatialization equaled 0.91 and mean error percentage was 16.5%.

Soil erosion is a severe problem in sloping land of hilly red area. Based on 137Cs tracing technique and by some soil erosion estimating models, the soil erosion rate on the representative sloping lands of Fengcheng City, Jiangxi Province was studied. The results showed that the reference inventory of 137Cs in the study area without soil erosion or man disturbing is 1 992.45±145.63 Bq/m2 . The annual soil erosion occurring on different parts of slope is evidentily different, with its rate increasing in the order form top of slope, middle of slope and to bottom of slope. Under different land use types, the average soil erosion rates are also different, which decreases in the order from, cultivated sloping land, multislope of conversion from farmland for 30 a and 1 a, slope of conversion from farmland for 30 a and barren slope. This result is benefitial for making relative land use, water and soil conservation policy for the ongoing national reducing cultivated land to forestland and grassland project in the study area.

Based on the farm household′s questionnaire in Shangrao County of Jiangxi Province, the paper analyzed the mechanism of farm households′ behavior of WSCI. Factors, influencing mostly farm household's behavior of WSCI are: regional economic development, partfarm behavior of farm households, agricultural land area and quantities of family agricultural labor. In order to analyze the relativity between farm household′s behavior of WSCI and these parameters, a linear regression model was established by the software SPSS. Farm household′s behavior of WSCI was mostly influenced by partfarm behavior, income structure and agricultural land area of farm households. Partfarm households, who had more income from nonagriculture, invested less in water and soil conservation. And farm households with more agricultural land area also paid less attention in investing water and soil conservation. At last, some pieces of advice were given to prompt farm household′s behavior on WSCI.

The authors take Jiangxi Province as an example to test the response of soil and water losses on regional agricultural market liberalization. Based on the analysis of study area, the paper establishes a model including the driving factors of soil and water losses. This paper analyzes the contribution of regional agricultural market liberalization from 1988~2000 to the decreasing of soil and water losses. The research result shows that, accompanied with local agricultural market liberalization increasing 15.2% from 1988 to 2000, the area of soil and water losses decreases 61.447 1×104 hm2, which is 18.36% of total area of soil and water losses in 2000. If local agricultural market liberalization increases 1%, the area of water and soil losses will decrease 4.043×104 hm2. So regional agricultural market liberalization benefits from the decreasing of soil and water losses. Finally, ameliorative measures for the soilwater losses are given.

In this article , the interaction among biosystem, soilsystem and watersystem in the whole ecologicsystem of lowland lake field are described. And in the mean time, the soil characters, potential resource dominance about lowland lake field are analysed. Lower water and soil temperature, bad aerate penetrability and worse structure cause soil presenting strong reducibility. Containing large amount of toxic reducing substance, the soil went against growth of crops such as rice. The amount of microorganism lower than normal soil observably, organism in the soil mineralization is very slowly, the nitrogen supplying is weakness too, lack of phosphorus and zinc fearfully. The biocharacter of aquatic economical plant nelubo nucifera possesses dominance of upgrowth spiracle which assuring the need of respiration and metabolization for the plant in the water, in the mean while, improving aerate penetrability and estate of reduceoxidation, enhancing activity of the soil microorganism accerlerating mineralization of the organism. In terms of ecosystem advantages in lowland, cropsystem, soilsystem and watersoil system was compared and analysised,with the results of crop biomass: Nelumbo nucifera﹥Zizania caduciflora﹥Trapa bispinosa﹥Oryza sativa,and crop yields: Nelumbo nucifera﹥Zizania caduciflora ﹥Trapa bispinosa﹥Oryza sativa.Dominant in crop system was optimized,and the key nutrient elements were regulated (N:P:K 16:16:16).According to the characyeristics of watersoil system, biological coexistence model was constructed, and the measures to make fall use of resource advantages in lowland lake as well as the developmental model were put forword. These would help improve the whole level of the ecosystem′s integrative developmental benefit in lowland lake.

Wuli Lake is one of the most seriously polluted areas of Tai Lake. For the remediation purpose, upper layer sediments, column sediments, interstitial water and lake water from 4 different locations in Wuli Lake were sampled, and the concentrations of heavy metals and nutrients in the samples were tested. The results indicated that heavy metals pollution level was slight compared with the Environmental Quality Standard for Soils（GB15618-1995）, when calculated with Igeo method. The heavy metals ranked in descending order of concentration was Cu>Cd>Pb>Hg>As>Cr. The concentrations of heavy metals in upper layer（0～5 cm） were lower than those in the second（5～10 cm） and third（10～20 cm） layer, which demonstrated as dominant contaminated deposit layers. The phenomenon was correspondent with the deposit characteristics of sediments. The concentrations of TN, TP and OM in upper sediments were high and an obvious correlation between these parameters could be found with the correlation coefficients were between 0.757 6 and 0.862 2. The concentrations of nutrients in sediments and interstitial water were much higher than those in water lake, which highlighted eutrophication as the most important endogenetic water pollution sources in Wuli Lake.

The Le′an River is one of a number of rivers flowing into Poyang Lake. The Dexing Mineral Factory which located near the Le′an River is one of the largest mineral factories in our country and is the main pollutant source of heavy metals in the Le′an River and Poyang Lake . A survey on the contents of heavy metals in water,sediments and aquatic plants was conducted to evaluate the contamination of heavy metals. The heavy metals such as Cu、Zn、Pb、Cd and their compounds were determined.The results indicated that the water in the investigated areas was not contaminated by heavy metals，and the water quality meets to the first evaluation criterion of surface water. But the content of heavy metals of Cu、Pb、Zn in sediments and soils are relatively high.And different plants have different selective enrichment of heavy metals .The enrichment coefficient was correlated to the background of heavy metals in soils,the higher concentration of heavy metals in soils,the more enriched of heavy metals in aquatic plants.

Xiangxi River is the longest tributary in Hubei region of the Three Gorges Reservoir. The health condition of the river may influence water quality of the reservoir. So, it is meaningful to study how to manage the Xiangxi River ecosystem. While, being a new field in river ecology, river ecosystem management is undergoing development, and how to conduct the research deserves exploration. In this article, the authors introduce firstly the state of the art of relative research in brief. Then, based on the fact that Xiangxi River was mainly affected by constructions of hydropower stations, unreasonable exploitation of land in the watershed, and industrial pollution, etc，we suggest that guaranteeing quantity and quality of water should be the principles, and maintaining healthy river ecosystem and fulfilling its all services should be the objectives of all management research and measures. Following the idea, four research aspects for Xiangxi River ecosystem management can be carried out, including ① ecological planning of land use of Xiangxi River Watershed; ② management of hydropower stations on the Xiangxi River; ③ pollution control of Xiangxi River Watershed; ④ monitoring and evaluation of ecosystem health and services of Xiangxi River.

The water resource is one of the most important basic aspects in supporting social economy development in karst areas. The scientific foundation will be offered for disclosing the law and the controlling mechanism of the formation and evolvement of water resource in karst areas for building the system theory of evaluation, exploitation and protection of the water resource, and for exploring the sustainable utilization models of the water resources. Based on the analysis of the typical kind of ecological system and its evolvement characteristics in karst mountain area and the characteristics of karst water resource, the changes of ecosystem in last 20 years in West Hunan,and the effects of ecological system on karst water resources are discussed in detail. It is considered that the worsening of ecological system is an important factor in the lack of water resource in karst mountain area, and the ecological environment change results in the change in quantity and quality of karst water through the effect on the recharge, runoff and drainage of karst water.

Effective acquisition and realtime extraction of data has always been a difficult problem in the study of regional ecological security and geographical processes．Based on the analysis of spectrum information of TM imageries for Zhongxian County，three main factors were extracted from remote sensing imageries：land cover，the extent of water and soil erosion and vegetation cover. The security indicator system of ecological and environmental system in mountainous area on county scale was analyzed．Then spatial analysis of these indicators was carried out by GIS．Technology and methodology were developed in the acquisition and extraction of security indicators of ecological and environmental system in mountainous area on middlescale county．This paper presented the temporal and spatial differences of some ecological security indicators in Zhongxian County and provided a new method for the evaluation of ecological and environmental degradation and ecological and environment recovery in mountainous areas．

With the Yangtze River being dammed, the Three Gorges Reservoir Area starts to impound water for the first time. It is well known that the construction of the Three Gorges Project attracts the attention of the world. On the basis of the sufficient social investigation and the correlative theories of regional economy and environmental administration, this paper discusses conditions of the environmental safety and security in the Three Gorges Reservoir Area, thoroughly analyzes the defects of current law enforcement mechanisms (including law observation, law enforcement, law application and law supervision), and puts forward suggestions on the construction and perfection of law enforcement mechanisms of environmental safety and security protection. The suggestions are as follows: We could offer environment protection education and technique assistance to the main body that abides by law. In order to improve the observance of the law, we could consummate the public participation mechanisms to get the support from the public. We could establish scientific, effective and unified Reservoir Area's law enforcement mechanisms of environmental safety, make clear the responsibility of the Reservoir Area's administrative law enforcement main body, set up the overt exposition mechanism of the administrative law enforcement, perfect the service mechanism of law enforcement main body, and build the green information internet. We could popularize the environmental group lawsuit, extend the defendant range of the environmental group lawsuit, and reform the advance payment way of the environment litigation cost.

The middle reaches of the Yangtze River is the central area of the Yangtze River industrial belts and an important area to form a connecting link between the east and the west of China. However, since 1990’s, the frequency of flood disasters and the economic loss caused by floods has increased continuously. Although flood disaster is closely related with physical factors, such as weather, geomorphology etc., unreasonable land use by human has increased the occurring possibility and intensity of flood disaster. By analyzing the relationship between land use and flood water level, the capacity of regulating flood of lake and river, and the economic loss, it is found that the unreasonable land exploitation and utilization of the flooddiversion and floodstorage areas, the building of sluices to reclaim land from lakes, and the exploitation of islets in the river are the key factors of land use in the middle reaches of Yangtze River to aggravate flood disasters. Therefore, some land use policies，such as compiling land use planning in areas fragile to flood disaster, carrying out the policy of “conversing agricultural polders to lake, emigrants for town construction”, developing “antiflood agriculture”, constructing flooddiversion and floodstorage areas, and improving land use efficiency, etc, are proposed for mitigating flood disasters. Furthermore, the possibility implement these policies and some problems to be resolved in the process of their implementation are analyzed.

It is necessary for agricultural development to mitigate huge agricultural flood disaster risk in the plain of the middle reaches of the Yangtze River. By studying on agricultural land system and risk characteristics of the Chinese farmers' management in this article, it was concluded that there were defects of micromanagement and no actuating mechanism of property in China's agricultural system. Farmers had no way and no ability to mitigate huge flood disasters, and they actually were to be evaded managers under exocircumstances of agricultural risk share. Government must be leader to mitigate and share agricultural flood disaster risk. On this ground, this article has put forward policies of agricultural flood disaster risk management: (1) to strengthen agricultural ecological environment construction, and to preserve land and water in superior and middle reaches of the Yangtze River, and to recovery ecological marsh system; (2) to develop agriculture mitigated flood disaster, and to achieve excelling of regional agricultural structure; (3) to apply active financial policies to increase agricultural investment; (4) to amplify farms' capability to mitigate natural disasters by agricultural policy's insurance shared risk of agricultural flood disasters in the plain of the middle reaches of the Yangtze River.