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    15 December 2015, Volume 30 Issue 12 Previous Issue    Next Issue
    Theoretical Discussion
    Analysis of the Definition, Classification and Ecological Function of Wasteland
    GONG Li-yan, CHENG Lei-lei, LU Qi
    2015, 30 (12):  1969-1981.  doi: 10.11849/zrzyxb.2015.12.001
    Abstract ( )   HTML ( )   PDF (718KB) ( )   Save

    About one-third of land in the world is approximately the basic conditions of waste-land. Wasteland is very wide and has a pivotal position on earth. Meanwhile, it bears very important ecological functions. In recent years, Chinese government and academia paid much attention to the wasteland. Protection and development of wasteland had become an important research topic. Although China has had a lot of provisions on wasteland, and scholars have carried out relevant research on wasteland from different aspects, the definitions and classifi-cations of wasteland are not unified. This hinders the protection and development of wasteland to a certain extent. Firstly, this paper reviews existing definitions of wasteland and clarifies the relationship between wasteland and other related concepts, and then redefines the concept of wasteland: generally wasteland refers to unutilized, idle or abandoned land except for agricultural land and construction land. In the narrow sense wasteland refers only barren state of land, but with appropriate use it could be suitable for agriculture, forest, herd and energy corps. Secondly, this paper systematically analyzes the classification of wastelands in the United States and India, and on the basis of existing land classification system in China, it proposes to add the category of “ecological land”, which plays the main ecological functions, provides ecological services and ecological products of woodland, grassland, wasteland, water and beaches directly or indirectly. At the same time it proposes to divide wasteland into three types: wilderness, unused and abandoned land. Thirdly, this article first recognizes that waste-land has various ecological functions, such as sand-fixation, soil conservation, carbon sequestra-tion and oxygen release, water conservation, biodiversity conservation, etc., which has impor-tant implications for the development and protection of the ecological land and wasteland. Finally, this paper proposes four suggestions on the development and protection of wasteland in China in the future: pay attention to the value of wasteland, establish the property right system of wasteland, prepare the natural resources balance sheet, protect and develop wasteland by categories.

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    Natural Resources and Economic Growth: Based on the Threshold Effect of Financial Development
    LIU Yao-bin, HUANG Meng-yuan, BAI Cai-quan
    2015, 30 (12):  1982-1993.  doi: 10.11849/zrzyxb.2015.12.002
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    “Resource curse” is a classic hypothesis in economics, but the impact of financial development on “resource curse” is always ignored. This paper reveals that financial development threshold exists in the “resource curse” through theoretical level, using Hansen threshold model based on the panel data of China 's 31 provinces over the period of 1996-2012. There is evidence that inter provincial “resource curse” does exist in China; a threshold of financial development exists in economic growth, namely the development of the financial sector before and after the threshold 1.6352 has significant different impact on economic growth; household consumption and government expenditure have impact on the financial industry significantly; physical capital investment is still the important factor that affects China 's economic growth. Therefore, stimulating local consumption, increasing government expendi-ture and investing in physical capital can improve the development level of regional financial industry, when the financial development is over the threshold, natural resource can effectively promote economic growth through the optimal configuration of the financial sector, so that can effectively alleviate the “resource curse” phenomenon, and promote economic growth.
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    Resource Economics
    Study on Marine Ecological Compensation and Macroeconomic Effect Based on CGE Model: A Case Study of Shandong Province
    CHEN Dong-jing
    2015, 30 (12):  1994-2004.  doi: 10.11849/zrzyxb.2015.12.003
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    Based on CGE model which contains marine natural resources and marine infor-mation, Shandong Province is taken as an example to study the impact of marine ecological compensation, GDP, residents income, enterprise income, government income and residents welfare under different scenarios by using basic data from SAM. Firstly, the result shows that marine ecological compensation can be increased by increasing four exogenous variables, which are transfer payments rate from enterprise, transfer payments rate from residents, value-added tax rate, and transfer payments rate from government. The increase of transfer payments rate from enterprise has the most effect on marine ecological compensation, followed by the increase of transfer payments rate from residents, then the increase of value-added tax rate, and the increase of transfer payments rate from government has the less effect. For example, if four exogenous variables increase by 10% respectively, marine ecological compensation can increase 1.824%, 1.417%, 1.083% and 0.097% respectively. Secondly, the result shows that although increasing value-added tax rate can significantly enhance marine ecological compen-sation, it will cause an obvious negative macroeconomic effect that it leads GDP, enterprise income and residents’ welfare level to drop significantly. Thirdly, the result shows that the increase of transfer payments rate from residents, transfer payments rate from enterprise, and transfer payments rate from government each has less negative effect on macroeconomic than that of value-added tax rate. Finally, the result shows that the marine ecological compensation multipliers of marine natural resources supply, labor supply and economic capital supply are all positive (0.571× 108, 0.002× 108 and 0.002× 108 yuan, respectively), which means increasing the three types of primary production factors will all cause the enhancement of marine ecological compensation during the production.
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    Coal Resources Exploitation 's External Costs and Payable Taxes Comparative Analysis: A Case from Xinjiang
    SHI Le-le, ZHAO Jun
    2015, 30 (12):  2005-2017.  doi: 10.11849/zrzyxb.2015.12.004
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    External costs of coal resources exploitation include user cost and environment cost. The paper used user cost approach to estimate the user cost of coal resource exploitation in Xinjiang from 2003 to 2012, and compared it with payable resource taxes. It adopted market value method and restoration expenditure method to estimate the ecological environment cost of coal resources exploitation of Xinjiang in 2012, and compared it with the payable ecological and environmental fee. It was found that the levy of coal resource tax from the amount couldn 't effectively compensate for the coal resource depletion in Xinjiang. It appeared significant intergenerational externalities. However, using ad valorem tax approach was able to effectively compensate it. The compensation rate of coal exploitation ecological environment costs was 29.6%, which couldn 't effectively compensate for the loss of value of ecological environment for coal exploitation. The study found that the existing standard of coal resources tax in Xinjiang couldn 't completely solve the problem of externalities of coal exploitation. Moreover, in the situation of “instead of fee with tax”, coal resource tax rate set at 6% was slightly lower. Finally, it was suggested that local governments should set the reasonable coal resources tax rate at different reform stages. China should establish ecological compensation mechanism as soon as possible, be timely for environmental tax reform, and improve the accounting system of coal resources price.
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    Resource Evaluation
    Temporal and Spatial Variation of the Potential Agricultural Productivity of China under Global Climate Change
    ZHONG Zhang-qi, WANG Zheng, XIA Hai-bin, SUN Yi, YUE Qun
    2015, 30 (12):  2018-2032.  doi: 10.11849/zrzyxb.2015.12.005
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    Potential agricultural productivity has an important and far-reaching impact on re-gional agricultural development and agriculture industrialization investment and distribution. However, previous researches paid more attention to exploring the potential agricultural productivity in some regions of China, but the temporal and spatial variation of regional potential agricultural productivity in China have yet to receive the attention they deserve. Furthermore, more importantly, the study regarding the impact of climate change on the potential agricultural productivity and the spatial pattern of Chinese agricultural development are relatively small in China. Therefore, in allusion to the problems mentioned above, based on the GIS method, this paper analyzes the temporal and spatial characteristics of regional potential agricultural productivity of China since 1980s, and discusses the impact of climate change on potential agricultural productivity and food production in China between 2041 and 2060. Results mainly show that the regional potential agricultural productivity in southeastern China is higher than that of other parts of China between 1961 and 2012, and the lowest potential agricultural productivity is found in northwestern China. However, the averaged potential agricultural productivity is less than 7500 kg/hm; 2 in west regions of the HU-line in China. At the same time, spatial distribution of the averaged potential agricultural productivity in China between 1961 and 2012 clearly presents the characteristics of latitude zonality. In addition, by comparing two periods of 1961-1980 and 1981-2012, the decline of the potential agricultural productivity is mainly found in areas east of the HU-line, and the largest declines are found in Sichuan Basin and in the middle of North China Plain, falling by more than 4%. Notably, however, the biggest contributing factor leading to reduce of potential agricultural productivity in these regions is the availability coefficient of water. Moreover, the middle and lower reaches of the Yangtze River and the south of North China Plain are characterized by increasing potential agricultural productivity. Finally, the simulated results suggest that the decline in the potential agricultural productivity of China between 2041 and 2060 can be mainly found in the area south of the Yangtze River and in the middle of Qinghai under the context of global climate change, where Sichuan Basin, southern and central Hubei would be the most declined regions in potential agricultural productivity, which means that future climate change may have a significant negative effect on food production in these regions.
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    Variation of Coastline Resources Utilization in Chinafrom 1990 to 2013
    LIU Bai-qiao, MENG Wei-qing, ZHAO Jian-hua, HU Bei-bei, LIU Li-dong, ZHANG Feng-shou
    2015, 30 (12):  2033-2044.  doi: 10.11849/zrzyxb.2015.12.006
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    The coastlines of China were extracted using remote sensing and GIS techniques based on remote sensing images of Landsat TM, ETM+ and HJ-1A between the year of 1990 and 2013. Then the spatial-temporal changes of the length and utilization intensity of coastlines were analyzed. For the purpose of sustainable use of coastline, two evaluation indices that are utilization intensity and resources’ vulnerability were put forwarded. The results show that: 1) the length coastline of China increased 1045.54 km during the research period. A large number of natural coastlines were changed into artificial coastlines, so the length of artificial coastlines increased by 4398.14 km. The proportion of artificial coastlines in China reached 56.29% in 2013. 2) The intensity of coastlines utilization was increasing in the past two decades. The proportion of developed and utilized area within one kilometer to coastline has reached 80%. The length of heavily used coastline is 3118.05 km, accounting for 16.43% of the total length. The heavily used coastline in Hebei, Tianjin, Shandong, Shanghai, Jiangsu and Zhejiang respectively takes more than 50%, and the unutilized coastline takes less than 30% of the length in each province. While the unutilized coastline in Hainan, Fujian and Guangxi all take more than 60% of the length. 3) The coastlines with low vulnerability mainly distribute in Fujian, Guangdong, Hainan and Shandong. Highly vulnerable coastlines account for more than 15% in northern coastal areas except Shandong Province.
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    Spatial Pattern and Club Convergence Analysis of Urban Expansion in Beijing-Tianjin-Hebei Urban Agglomeration
    ZENG Xin-man, LIU Hui, LIU Wei-dong
    2015, 30 (12):  2045-2056.  doi: 10.11849/zrzyxb.2015.12.007
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    As the urbanization in our country has entered into a new rapid stage, urban agglomeration has become an important form of urbanization. Taking urban agglomeration as the subject, to research the spatial and internal differentiation characteristics of urban land expansion is the key to improve the quality of urbanization and achieve the coordinated and sustainable development of urban agglomeration. Based on four interpreted Landsat TM/ETM+ images (obtained in 1990, 2000, 2005, and 2010, respectively) and urban expansion index, we apply spatial analysis and econometric models to study the spatial pattern, regional differentiation and space club convergence of urban expansion in Beijing-Tianjin-Hebei Urban Agglomeration during 1990-2010 from the perspective of spatial effect. Firstly, the interpreta-tion of remote sensing images and the analysis of urban land-use changes show that from 1990 to 2010, urban land area increased about 4133 km2 in the urban agglomeration and the average annual expansion speed in 1990-2000, 2000-2005 and 2005-2010 was about 124, 172 and 407 km2, presenting an accelerating tendency. Then the spatial variation of urban land expansion is explored by spatial buffer analysis. The result shows that urban lands expand rapidly around the central area and along the highway, presenting circular and axial modes of expansion. Moreover, the urbanization intensity index is employed to describe the spatial differentia of urban expansion, which is calculated and classified into five categories. The maps show that urban expansion presents obvious spatial concentration and differentiation. In addition, significant spatial autocorrelation has also been found by using Moran��s I. Finally, the new concept of the spatial club convergence model is introduced into land expansion study. The spatial panel data analysis found space club convergence in L-L, L-H and H-H regions, and the convergence in L-L and L-H regions being significant (P< 0.001). Nevertheless, the H-L region has not converged. It concludes that setting new core cities among slowly development area will have a positive effect on neighbors. This analysis can be used in further studies on expansion mechanism of urban agglomeration, and provide the government with scientific reference on rational urban expansion and integrated planning of Beijing-Tianjin-Hebei Urban Agglomeration.
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    Temporal and Spatial Variation of Land Ecosystem Health Based on the Pressure-State-Response Model:A Case Study of Pinggu District, Beijing
    HE Xin, JIANG Guang-hui, ZHANG Rui-juan, MA Wen-qiu, ZHOU Tao
    2015, 30 (12):  2057-2068.  doi: 10.11849/zrzyxb.2015.12.008
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    Data resources and assessment frameworks are key requirements for ecosystem health assessment. High-precision land-use survey data ensuring the accuracy of results is introduced in this paper. In terms of assessment frameworks, the Pressure-State-Response (PSR) model can incorporate both the influence of human factors and the response of the environment. Under the PSR framework, a Vigor-Organization-Resilience-Service (VORE) assessment index system is developed to diagnose the regional land ecosystem health in Pinggu District of Beijing. The same-sized grids that present land ecosystem health on a diminutive scale was used as the assessment unit. Spatial distribution characteristics of land ecosystem health were analyzed using spatial autocorrelation. The conclusions are as follows: more than 70% of the total area had a health condition equal to or better than Level III. A slight decline in ecosystem health condition occurred between 1993 and 2011; the average value of ecosystem health condition was 0.59 in 1993 and 0.57 in 2011. In general, ecosystem health within Pinggu District was good. Urbanization and industrialization processes have led to the deterioration of land ecosystem health in the central urban area. In the central hilly areas, the nature reserves have helped to improve the local land ecosystem health condition. In addition, the increase in environmental management investment has improved land ecosystem health condition in the southern plains. There is still considerable spatial heterogeneity in land ecosystem health throughout the region. The paper concludes that the ecosystem health condition in the hilly and mountainous areas is superior to that in plain areas. Global Moran’s I was 0.49 in 1993, and increased to 0.61 in 2011. Greater spatial agglomeration resulted in an increase in the Global Moran’s I. In plain areas, Global Moran’s I for ecosystem health condition increased from 0.42 in 1993 to 0.46 in 2011. In hilly and mountainous areas, Global Moran’s I for ecosystem health condition increased from 0.41in 1993 to 0.46 in 2011. The results indicate that the ecosystem health condition in plain areas is declining, and that of hilly and mountainous areas has markedly improved. Human factors play a critical role in land ecosystem health. In plain areas, human influence leads to the replacement of natural and semi-natural landscapes with highly modified landscapes. Nevertheless, human factors have also made major contribution to the natural landscape in the hilly and mountainous areas near the Sizuolou region through the construction of a natural conservation area. As the emergency water sources and ecological conservation areas, Pinggu District should put emphasis on three key regions to improve its ecological condition. It is essential to maintain ecosystem health near Sizuolou region. Through the construction of ecological corridors, the “isolated island” effect of the reserves can be avoided. As for the hilly and mountainous areas where land ecosystem conditions become worse, the paper recommends to make full use of its resources advantage to coordinate the economic development and the ecological construction. The expansion of the central urban area in Pinggu District should be limited to alleviate the pressure of the land ecosystem. Ecological land consolidation in the central areas is necessary to achieve the goal of sustainable development.
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    Carbon Emission and Its Influence Mechanism of Rural Household Energy Use in the Coal Mining Area
    WU Wen-heng, ZHU Hong-ying, ZHANG Xin, ZHANG Jing-sa
    2015, 30 (12):  2069-2080.  doi: 10.11849/zrzyxb.2015.12.009
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    Studying the carbon emission of coal mining area helps better understand and draw up the related policies of rural carbon emission reduction. Taking Baishui County of Shaanxi Province as an example, carbon emission and its influence mechanism of rural household energy use in coal mining areas are quantitatively probed into by questionnaire survey and comparative analysis. The questionnaires, face to face in-depth interviews and case studies are conducted in Qixiu and Panjia villages, Xigu township in a coal mining area, and in Taixiang village of Yaohe township, Tangzhai village of Shoushui township, and Fuzhuo village of Leiya township which are non-coal mining area as well. Three hundred and twenty one valid question-naires were collected, among which 165 are from the former group and 156 are from the latter group. The data collected include population per household, crop production and yield, type and quantity of energy use, energy apparatus, household income, and so on. Case studies were conducted by weighing the consumption amount of crop straw, firewood and coal per house-hold per day or days. Annual energy supply and demand per household are calculated by the weight of crop straw, firewood and coal, and by the actual measured quantity of coal, electricity, biogas, etc. The results show that the carbon emission (1639.56 kg C/household) of rural household energy use in the coal mining area is less than that (1747.77 kg C/household) in the non-coal mining area. The former is mainly from coal, firewood and electricity, which con-tribute to more than 96% of the total energy used. What’s more, the proportion of carbon emission from coal is up to 61.72%. The latter is primarily from firewood, coal, crop residues and electricity, which is more decentralized and diversified. On the whole, the carbon emission of firewood takes the highest proportion (41.30%). In the meantime, the commercial energy consumption of household (1443.2 kgce/household) in the coal mining area is more than that (1014.47 kgce/household) in the non-coal mining area. Through the above, there is no indica-tion of increased carbon emission caused by commercialization of energy structure in the coal mining area. Further, it might be seen that the carbon emission is directly related to types and quantity of energy used, and emission coefficient as well. That is to say, the more usage of carbon emission energy, and the greater the emission coefficient, the larger the carbon emission is. As far as the influence mechanism of carbon emission is concerned, coal mining is the root cause and main inducement that lead to the differences of rural household energy use and carbon emission between coal mining area and non-coal mining area. At last, several measures are put forward, which include improving energy cookers and promoting thermal effect, increasing the consumption of biogas, and paying close attention to different emission effect between different regions.
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    Evaluation and Spatial Analysis of Tourism Resources Attraction in Beijing Based on the Internet Information
    ZHU He, LIU Jia-ming, TAO Hui, ZHANG Juan
    2015, 30 (12):  2081-2094.  doi: 10.11849/zrzyxb.2015.12.010
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    Traditional research methods of tourism attraction have some disadvantages, such as difficult data acquisition, poor market evaluation and different tourists’ experience. The development of internet brought us new approach. Taking Beijing as an example, this paper collected relevant information from internet, and classified tourism resources in Beijing according to the established classification system of urban tourism resources. Analytic hierarchy process (AHP) was used to establish a tourism resources attraction evaluation system, and the attraction of tourism resources in Beijing was evaluated. Then we analyzed the spatial pattern of tourism resources’ attraction by density estimation and spatial autocorrelation, and the following conclusions were found: 1) the total number of tourism resources in Beijing is 415, including 108 natural tourism resources, 203 humane tourism resources, 104 leisure tourism resources, and the average of tourism attraction of all resources is 0.32, among which humane tourism resources have taking the largest number and the highest tourism attractive index. 2) There is spatial agglomeration of the attraction of tourism resources in Beijing. The spatial agglomeration degree of leisure tourism resources is the largest, and that of humane tourism resources is the minimum. 3) The distribution of natural tourism resources is more uniform, with multiple density centers of tourism attraction, attractive hotspots mainly locating in the main city; humane tourism resources are concentrated in the main city, and forms the highest attractive density center, the primary and the secondary hot spots being alternatively distributed; leisure tourism resources are concentrated in the main city with the primary hotspots of attraction surrounded by the secondary ones, leaving cold spots in surrounding country areas, and their attractive density center is also in the main city. This paper put forward a evaluation system of tourism attraction based on internet information, which will be a new and convenient approach for tourism attraction research. It will be of some significance to the development of tourism resources.
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    Impact of Global Warming on Vegetation Activity in Ningxia Province from 1982 to 2013
    DU Ling-tong, SONG Nai-ping, WANG Lei, HOU Jing, HU Yue
    2015, 30 (12):  2095-2106.  doi: 10.11849/zrzyxb.2015.12.011
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    Global warming has been proved to be good for plant growth in middle and high latitudes regions in northern hemisphere. However, the responses of vegetation avtivity to climatic changes varies considerably in different ecosystems and regions. Being a typical arid and semi arid area in China, Ningxia Province is located at farming-pastoral ecotone in northern China and has complicated pattern of vegetation cover. Thus, studying on the impact about the vegetation activity in this etfect of global climate changes are of great significance and would help understand the responses of agro-pastoral ecosystem to global climatic changes in northern hemisphere. Based on vegetation health product (VHP) dataset during period of 1982-2013 derived from advanced very high resolution radiometer (AVHRR) on board of national oceanic and atmospheric administration (NOAA) satellites, this study combined methods of Mann-Kendall nonparametric test, rescaled range analysis and ensemble empirical mode decomposition to quantify the impacts of climate warming on vegetation activitives in the study region. The results show that weekly surface brightness temperature (BT) of Ningxia Province significantly increased from 1982 to 2013. An abrupt turning point of weekly temperature condition index (TCI), which is detected by Mann-Kendall nonparametric test, occurred in 1995 when the trend of climatic change shifted from fluctuation to persistent warming. The weekly normalized difference vegetation index (NDVI) increased 0.078/10 a (P<0.01), the speed of which was faster than that in the Three-North Shelter Forest. An abrupt turning point of the weekly vegetation condition index (VCI) was also detected which occurred in 1990. The vegetation activity in Ningxia was degrading before the turing point, while abruptly changed to restore after that. The correlation analysis indicated that there is no significant statistical correlation between VCI and TCI before 1995, which suggested that the climate warming had no obvious impact on vegetation activity in Ningxia Province. However, the significant negative correlation (P<0.01) between VCI and TCI during 1995-2013 suggested that the increase of land surface temperature enhanced the vegetation activity. The impact of climate warming on vegetation activity after 1993 are different in intensity in four seasons, the order from strongest to weakest being autumn, winter, spring and summer. Two main factors were responsible for the change of climate warming’s impact on vegetation activity in 1995: firstly, a abrupt climate change happened in 1995, when the trend of climate changed from fluctuation to continous warming in Ningxia Province; secondly, a series of irrigation projects and ecological restoration projects were implemented by the province goverment, which changed the regional vegetation distribution patterns in the middle and late 1990s. All these changed the main constrain factor of vegetation activity from water to heat.
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    Variation Characteristics of Water Requirement of Cotton in China during 1961-2012
    CHEN Chao, PANG Yan-mei, PAN Xue-biao, ZHANG Li-zhen
    2015, 30 (12):  2107-2119.  doi: 10.11849/zrzyxb.2015.12.012
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    Based on the observation data from 230 meteorology stations and cotton phenology data from 103 agrometeorological stations in the three major cotton producing regions of China, the water requirement of cotton throughout the whole growing period and in each growth stage during 1961-2012 were estimated by using crop coefficient and FAO Penman-Monteith equation. Further, the water deficit and water budget index in each growth stage of cotton were analyzed in the study area. The results showed that the average water requirement and water deficit in northwest region during 1961-2012 were greater than that in Huang-Huai-Hai and Yangtze River Valley regions. The average water requirement and water deficit from flowering to boll opening stage was the highest, followed by that from sowing to flowering stage, and that from boll opening to maturity stage was the least. The water requirement and water deficit during the whole growing period from 1961 to 2012 decreased in this region. The water requirement decreased in the period from flowering to boll opening stage, but it had no change from sowing to flowering stage and from boll opening to ripening stage. The water deficit of cotton decreased in the period from sowing to boll opening stage, but it had no change from boll opening to ripening stage. Comparing the water budget index of typical stations in different study regions, the effective precipitation during the whole growing period and the different growth stages all couldn’t meet the demand of cotton, and the most serious water shortages occurred in the northwest region. This research can provide the basic scientific support for better agriculture water use and reasonable irrigation in the cotton growing regions of China.
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    Resource Research Method
    An Improved Calculation Method of Grey Water Footprint
    WANG Dan-yang, LI Jing-bao, YE Ya-ya, TAN Fen-fang
    2015, 30 (12):  2120-2130.  doi: 10.11849/zrzyxb.2015.12.013
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    Presented by Hoekstra in 2002, grey water footprint is a method which describes the pollution status in quantitative way. Grey water footprint is defined as the fresh water volume needed to dilute the pollutant to the maximum concentration allowed by relevant water quality standards. Although this theory provides a new way to assess the condition of water environment pollution, it has several problems when taken in practical application. Firstly, the traditional grey water footprint computation does not consider the fact that the pollutant is usually diluted by different water bodies, so the result figured out only shows the total grey water footprint but fails to reflect the pollution severities of different water bodies; secondly, equating massive discharge of pollutant with large grey water footprint can lead to an incorrect computing result of grey water footprint. On account of these reasons, an improved computing method of grey water footprint is hereby presented. The improved method is a two-step ap-proach, which takes into consideration the fact that the same pollutant can be diluted by several water bodies, and attaches much importance to different demands on different pollutants by water quality standard, thus it can distinguish the two concepts of large grey water footprint and massive discharge of pollutant. The improved method firstly divides the whole quantity of discharged pollutant into several different water bodies and calculates the grey water footprint of each water body based on the “maximal counts” principle, and then sums up the grey water footprints of different water bodies to get the final grey water footprint. The concept of water environment load index is also introduced, and it is defined as the ratio between grey water footprint value of certain water body and volume of that water body. The improved method can not only describe the distribution of certain pollutant in different water bodies such as river, lake, sea, reservoir and underground water, etc. and demonstrate the combination structure of pollutants in certain water body, but also reflect the pollution severities of different water bodies, so it makes the result more accurate. After empirical analysis of Hunan province with the improved grey water footprint, the following results are obtained: during the years 1985-2013, the grey water footprint increased from 133.0 billion to 224.8 billion cubic meters with a steady annual growth rate of 1.89%, and the grey water footprint of surface water accounted for 70%, while the underground water for 30% approximately. The grey water footprint of surface water was determined by ammonia nitrogen in 1985-1991 and by phosphorus in 1992-2013, while the grey water footprint of underground water was always determined by phosphorus in 1985-2013. During the 29 years, the environment load index of surface water was always lower than that of underground water, and the difference between the two varied from 0.41 to 1.03 then to 0.76 demonstrating an inverted U shape. It means that the environment condition of surface water was better than that of underground water during the research time period, and the gap firstly increased and then decreased.
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    Calibration of Parameters in Soil Moisture Equation with EnKF
    LI Chao, HUI Jian-Zhong, TANG Qian-hong, YANG Fei-Yun
    2015, 30 (12):  2131-2140.  doi: 10.11849/zrzyxb.2015.12.014
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    Ensemble Kalman Filer (EnKF) is a flexible and effective sequential data assimilation method. Appling EnKF to solve the parameter optimization problem has several advantages. Firstly, it explicitly considers multiple sources of uncertainty, thus avoids the excessive adjustment of parameters due to the compensation for errors arising from other sources, which will generate sub-optimal parameters. Secondly, it processes the latest updated observations, eliminating the storage and processing all the historical data simultaneously. Thirdly, it characterizes and predicts related error statistics by Monte Carlo method, thus no closed solution approach is needed, making it easy to build with existing numerical models. In this study, by simulation of observed data, EnKF is evaluated in terms of the effectiveness and efficiency of calibrating soil hydraulic function parameters in one-dimensional Richards equa-tion. The results show that, optimal parameter estimates can be easier obtained for more sensitive parameters. The performance is influenced by neither the initial surmises nor the observation error settings. Contrary to intuition, the increase of assimilation frequency may cause instable estimation results.
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