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Table of Content

    20 May 2016, Volume 31 Issue 5 Previous Issue    Next Issue
    Experts' Forum
    The LID Pattern for Maintaining Virtuous Water Cyclein Urbanized Area: A Preliminary Study of Planning and Techniques for Sponge City
    LIU Chang-ming, ZHANG Yong-yong, WANG Zhong-gen, WANG Yue-ling, BAI Peng
    2016, 31 (5):  719-731.  doi: 10.11849/zrzyxb.20151294
    Abstract ( )   HTML ( )   PDF (12703KB) ( )   Save
    Sponge city is an important Low Impact Development (LID) pattern, and also is a key to solve the urban water issues in China. In this study, we focus on the three core tasks including urban flood control and drainage, non-point source pollution control and urban rainfall-flood utilization, and explore the key technology and methodology to support the implementation of sponge city from the perspective of virtuous-water-cycle (e.g., the numerical simulation and LID optimization techniques), and finally develop an urban rainfall-flood model (HIMS-URBAN). This model is applied in Changde City, which is one of the first batch of sponge city. The results demonstrate that: 1) runoff coefficient in Changde City ranges from 0.33 to 0.81 in current state, with an average of 0.64. 2) Based on the objective of controlling total annual runoff, several LID measures (e.g., infiltration, storage and retention), are employed to consume the runoff from each block. By optimization, the controlling objective can be achieved in 90% of urban blocks. The areas of sunken green space, permeable pavement and green roof are 496.75, 1 338.15 and 613.21 hm2, respectively, and the total area of LID measures accounts for from 3.9% to 31.4% of each block’s area. The reduction rate of pollution load SS is between 45.0% and 47.7%, with an average of 46.1%. By adopting the LID measures, the outputs of storm runoff and the pollution load in Changde urban area are remarkably reduced, and the control objective is almost achieved. This study provides great valuable results for construction of sponge city in Changde City, and also gives a good reference of theory and technology for urban planning and design.
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    The Status of Silk Road Economic Belt in the World Oil Supply Pattern and Its Evolution
    ZHAO Yuan, SHEN Lü-yun, HAO Li-sha
    2016, 31 (5):  732-742.  doi: 10.11849/zrzyxb.20150613
    Abstract ( )   HTML ( )   PDF (3926KB) ( )   Save
    Promoting energy cooperation is the core and the strategic breakthrough of constructing Silk Road Economic Belt. Since it lacks of systematic analysis of the reserves, production, consumption and trade of oil resources in the Silk Road Economic Belt, this paper adopts boxplot analysis method to discuss the ranks of the main oil-producing countries in the economic belt in the world oil supply and their changes. Combining with their changing statues in oil supply-demand balance, this paper makes suggestions regarding China’s oil cooperation with main oil-producing countries in the belt. Results suggest that: 1) As to either the proven reserves, productions, R/P or exports, the economic belt is on top of the world, and is the primary sources of world’s oil supply growth; even in the diversified trend of world’s proven oil reserves and R/P, the status of the economic belt is still strong and outstanding, and in further polarized trend of world’s oil production and export, the leading superiority of Saudi Arabia and Russia is more prominent. 2) Most oil supply countries in the belt are large and medium sized countries, and are highly clustered, forming a core area along Persian Gulf and the Golden Triangle of “Russia-Kazakhstan-Azerbaijan” surrounding Caspian Sea, especially the region surrounding Caspian Sea where the strong growth has narrowed the its gap with the Persian Gulf region; the cluster of oil super supplies plays regional advantages for oil exporting countries to share regional energy infrastructures, and for oil importing countries to have more cooperation choices. 3) There are obvious fluctuations of oil production and exports, which are mainly affected by the changes of regional situation, OPEC production regulation and the fluctuations of domestic demands in oil supplying countries. 4) In the future, China should continue to take Persian Gulf countries as the major partners, and diversify the origins of oil; region surrounding Caspian Sea is another big strategic cooperator of China, where the emphasis should be focused on the cooperative construction of oil transport infrastructure; China should gradually construct a Golden Cooperation Triangle consisting of Russia, Kazakhstan and Azerbaijan to hedge the risk in cooperation. 5) The cooperation between China and India also needs to be strengthened in order to enhance the regional power in barging, and improve the regional oil transportation safety.
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    Resource Ecology
    Water Costs of Afforestation and Natural-restoration in China
    LU Chen-xi, ZHANG Jun-ze, ZHAO Ting-yang, CAO Shi-xiong
    2016, 31 (5):  743-754.  doi: 10.11849/zrzyxb.20150557
    Abstract ( )   HTML ( )   PDF (3052KB) ( )   Save
    It’s well known that a healthy ecosystem has potentials in conservation of water and soil, prevention of wind erosion, refining regional water environment, regulating climatic, reducing pollution, increasing recreation and cultural protection, and other ecosystem services. However, ecological environment restoration and construction not only demands a huge amount of investment, but also takes up large quantities of water and soil resource. In order to properly figure out the costs of afforestation programs, for the first time, in this paper we used seven evapotranspiration models to calculate the water consumption of afforestation and natural vegetation and the water cost of afforestation since 1949. We found that the water consumption of afforestation was more than that of natural vegetation by 767×108 m3, and the accumulative opportunity cost of water was 536×108 yuan. To maintain the ecological balance, any ecological restoration, especially artificial restoration, and socio-economic activities should spare no efforts to pay attention on water cost. It is an essential issue encountered by restoration ecology to minimize the cost of restoration and improve the net value of ecosystem service by comparing cost-effectiveness of different measures.
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    Analysis on Dynamic of Carbon Storage in Tibet Attributable to Land Use and Land Cover Change
    ZHAO Zhong-he, XU Zeng-rang, CHENG Sheng-kui, LU Chun-xia, LIU Gao-huan
    2016, 31 (5):  755-766.  doi: 10.11849/zrzyxb.20150447
    Abstract ( )   HTML ( )   PDF (6454KB) ( )   Save
    There is a prominent impact of land use/cover change (LUCC) on dynamic of carbon storage and sequestration in ecosystem. The LUCC influence carbon storage via two ways, one is land conversion, the other is land modification. Studies have focused on the former, while the exploring of the latter is scarce. Located in hinterland of the Qinghai-Tibet Plateau, Tibet is typical ecologically fragile and sensitive area. Dynamic of carbon storage in Tibet and the contribution from land conversion and land modification was analyzed in the period from 2001 to 2010 in this paper. With the land cover data from MODIS MCD12Q1, the biomass density from the Carbon Dioxide Information Analysis Center (CDIAC), the soil organic carbon density from the Joint Research Centre (JRC), the carbon storages and sequestrations of Tibet in four carbon pools including aboveground biomass, belowground biomass, dead wood, soil carbon were calculated by using the InVEST (Integrated valuation of ecosystem services and tradeoffs) toolset. With quadrats data such as aboveground biomass and soil organic carbon collected through field survey and analyzed in-lab subsequently, the output of the model was calibrated. The main conclusions are: 1) The carbon storage increased 50 million tons from 2001 to 2010 in Tibet. Southeast Tibet and northwest Tibet experienced large changes in carbon storage with increasing in some areas and decreasing in others, while the middle and northern Tibet have relatively stable carbon storage. The carbon storage in farming areas reduced 39 million tons, and that in farming-pastoral area reduced 26 million tons, while that in pastoral area increased 114 million tons. Carbon storage in water conservation area and that in wind break and sand fixation area increased remarkably. Seen from the perspective of land cover type, carbon storage in grassland was continuously growing, and those in forest and sparse vegetation decreased slightly, while in shrub decreased remarkably. Carbon storage in grassland accounted for 57.1% and 62.1%, that in forest accounted for 11.8% and 11.1%, and in sparse vegetation accounted for 20.1% and 19.2%, while that in shrub accounted for 7.1% and 3.9% in total carbon storage of Tibet in 2001, 2010, respectively. 2) The land covers characterized with high carbon density increased in area, such as grassland and forest; those with low carbon density decreased in area, for instance shrub and sparse vegetation. The land conversion improved the capacity of carbon storage. Assuming the carbon density in each type of land cover being constant, the increased carbon storage caused by land conversion was 126 million tons, accounting for 269% of the carbon storage dynamic. 3) The land covers characterized with high carbon density, such as forest, decreased remarkably in carbon density, while those with low carbon density increased slightly in carbon density, such as sparse vegetation. Assuming that there is no land conversion, the decreased carbon storage caused by carbon density change was 79 million tons, accounting for -169% of the carbon storage dyna-mic.
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    Economic Valuation of Ecosystem Services Based on Choice Experiments: A Case Study of Wenjiang in Sichuan Province
    SHI Chun-na, YAO Shun-bo, CHEN Xiao-nan, XUE Cai-xia, GONG Zhi-wen
    2016, 31 (5):  767-778.  doi: 10.11849/zrzyxb.20150334
    Abstract ( )   HTML ( )   PDF (1718KB) ( )   Save
    Comprehensive economic valuation of the urban ecosystem service is important to urban ecosystem sustainable development. Taking Wenjiang in Sichuan Province as an example, this paper studied following aspects: firstly, basing on Choice Experiment method, the valuation indicators and the levels of different valuation indicators were selected and defined. The survey data were collected to show the local residents’ preferences for different indicators. Secondly, Mixed Logit model was used to calculate the total utility function of local residents’ willingness to pay for urban ecosystem service. And the implicit price and compen-sating surplus were calculated. Finally, the total economic valuation of Wenjiang’s urban eco-system service is figured. The empirical results show that: 1) The urban climate is the most concerned factor of Wenjiang’s local residents, then followed by water pollution, air quality, noise pollution and recreation. 2) The implicit prices of different ecosystem services are as follows: to achieve the 5-year goals, the marginal WTP of improving air quality, water quality, reducing noise polluting, improving local climate and increasing recreation are 399.45, 564.03, 295.25, 630.81 and 219.29 yuan per capita each year, respectively. 3) To achieve the 5-year goals, local residents’ compensating surplus is 113.59 yuan per capita each year. And the total economic valuation of Wenjing’s urban ecosystem service is 37.33 million yuan each year.
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    Study on the Compensation Standard of Returning Farmland to Forest in Xiannangou Watershed from the Perspective of Carbon Sink
    WANG Zheng-shu, WANG Ji-jun, LIU Jia
    2016, 31 (5):  779-788.  doi: 10.11849/zrzyxb.20150560
    Abstract ( )   HTML ( )   PDF (1437KB) ( )   Save
    Quantitatively formulating compensation standard is a core and difficulty to establish ecological compensation mechanism. In order to explore appropriate compensation standard for returning farmland to forest and provide reference for national and regional compensation policy formulation in the Loess Plateau, in the international background of the Clean Development Mechanism and logging ban policy, this paper builds a dynamic model of compensation standard for returning farmland to forest by combining value of carbon-sink with farmer’s opportunity cost. Through theoretical analysis and field measurements, combined with laboratory experiments, we made an empirical study of the representative watershed—Xiannangou Watershed on the Loess Plateau. The compensation cycle is determined to be 37 years according to the growth characteristics of the Robinia pseudoacacia forest in the Xiannangou Watershed. The compensation process and standard are divided into two stages. During the 1st-17th years of returning farmland to forest, when the farmer’s opportunity cost is greater than the value of carbon-sink, we should compensate for the actual economic loss of farmers. Executable standard of compensation is 1 997.26 yuan/(hm2·a) according to the oppor-tunity cost. During the 18-37th years of returning farmland to forest, the value of carbon-sink is greater than the farmer’s opportunity cost, which means that the industry substitution has completed. Executable standard of compensation is 3 692.35 yuan/(hm2·a) according to carbon sink model. In summary, the value of carbon-sink accounts for 89.50% of the total compen-sation in the compensation period. Artificial Robinia pseudoacacia forest will gradually generate shrubs and decline after the compensation period, therefore, the compensation standard should be calculated and perfected again in accordance with the change of forestland ecological community after the compensation period finished. Involving the value of carbon-sink into the compensation system can push farmers to manage and protect forestland consciously for improving the carbon sink production, which is beneficial to consolidate the achievements of the Grain for Green Program on the Loess Plateau.
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    Estimating the Values of Forest Ecosystems in Conserving Rare and Endangered Animals in Sichuan Province
    ZHAO Hai-feng, XU Ming
    2016, 31 (5):  789-799.  doi: 10.11849/zrzyxb.20150546
    Abstract ( )   HTML ( )   PDF (889KB) ( )   Save
    The value of ecosystems in conserving biodiversity, especially the rare and endangered animals (REAs), is an important component in the overall ecosystem values. However, directly estimating the values of ecosystem has been difficult and sometimes misleading. Thus, the current study used the costs of ex-situ conservation of the REAs to evaluate the value of forest ecosystems in protection the REAs in Sichuan Province to assist policy making in forest conservation and management. The approach is based on the alternative cost method, namely taking away the habitats provided by the forests, all the rare and endangered animals inhabited should be conserved by providing them with land, food, water, and other necessities. The costs of the ex-situ conservation represent the value of the forest ecosystems in protecting the REAs. According to the “basic” costs of individual animals in the Chengdu Zoo, we found that the total value of the forest ecosystems in protecting the REAs in Sichuan is 15.45×108 yuan in 2012.
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    The Interactive Mechanism of Urban Expansion and Economic Development in the Different Niche of Urban:A Case Study of Guangdong Province
    GUO Rui-min, QIAN Huai-sui, ZHANG Ling, LI Ming-xia
    2016, 31 (5):  800-811.  doi: 10.11849/zrzyxb.20150586
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    The process of urbanization tends to have phases. Urban expansions on different land use scales or in different regions have different phases, and their interactive mechanisms with economic development are significantly different. In this paper, 21 cities at prefecture level or above in Guangdong Province are taking as the study cases. According to the changes of their niche values in 1995-2010, the 21 cities are divided into four grades. Selecting the built-up area expansion as the indicator of urban expansion, the GDPs of the secondary and tertiary industries as the indicators of economic development, Kuznets curve, Logistic model, cointegration and Granger causality tests and decoupling theory are used to analyze the relationship between urban expansion and economic development. Four methods are combined to study the relationship between urban expansion and economic development in cities of different grades from different perspectives. The results show that the assumption of the relationship between urban expansion and economic development should be fully market-oriented, and various methods and multiple perspectives are necessary. Using the urban niche can properly distinguish the levels of the relationships between urban expansion and the economic development. The relationships between urban expansion and economic development in cities with different niches present different mechanisms. The relationships between urban expansion and economic development in most high niche cities meet Kuznets curve which can be fitted with a Logistic model, and there exists a long-term balance between urban expansion and economic development. Most high niche cities are in weak decoupling state. High niche cities occupy larger spaces and more resources, having higher levels of market, so the urban expansion has a closely relation to economic development. The relationships between urban expansion and economic development in most low niche cities do not meet Kuznets curve, however that in a few cities can be fitted with a Logistic model, and the long-term balance between urban expansion and economic development is not significant. Most low niche cities are in strong decoupling state. Low niche cities occupy small spaces and less resources, having lower levels of the market, so the relationship between urban expansion and economic development are not obvious although there is certain relationship. Currently, the sizes of most cities are close to the upper limit. High niche cities should take advantage of their management and techniques to constantly improve the resource efficiency and intensive level, so as to promote sustainable economic development. Low niche cities should gradually change the binary structure of urban and rural land and adjust the industrial structure to achieve sustainable economic development.
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    Resource Evaluation
    The Phosphorus Footprint and Its Environmental Analysis for Restaurant Food Waste:Taking Beijing as an Example
    ZHANG Dan, LUN Fei, CHENG Sheng-kui, GAO Li-wei, LIU Xiao-jie, CAO Xiao-chang, QIN Qi, LIU Yao, BAI Jun-fei, XU Shi-wei, YU Wen
    2016, 31 (5):  812-821.  doi: 10.11849/zrzyxb.20150500
    Abstract ( )   HTML ( )   PDF (2123KB) ( )   Save
    With the economic and society development, Chinese food demand has been increasing, while food waste also presents the same trend. However, food waste can not only influence national food security, but also bring in more serious problems, such as natural resource depletion, ecological degradation and environment pollution. Being the fundamental elements in human bodies, phosphorus (P) is a vital part of ecological nutrient cycle as well as urban metabolism. Besides, P can increase crop productions on one hand, and it causes P accumulation in soil and eutrophication of water body on the other. Thus, it is of high importance to research the P footprint on the restaurant food waste chain as well as their environmental pollution. We took the restaurant food waste in Beijing as an example to study the P footprint, and found out that: the amount of restaurant food waste in Beijing could reach 39.97×104 t/a, in which the content of P was 1.21×103 t/a; the P footprint of restaurant food in Beijingwas 40.56 g P/kg, i.e. when the food contains 1 kg of P was wasted, it would discharge 13.44 kg P into the environment; the total restaurant food waste in Beijing could reach 1.25×104 t/a and lead to 0.27×104 t/a of P discharged into the environment; for the whole restaurant food waste chain, the P flowing from food production (including crop products and livestock products) to the environment ranked the first. Therefore, consuming restaurant rationally and reducing food waste play important roles in food security and environment conservation.
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    Study on the Planting Industry Structure Adjustment and Its Impact on the Water Demand of Crops in Minqin Oasis
    ZHOU Jun-jü, SHI Pei-ji, LEI Li, CAO Jian-jun, WEI Wei, ZHANG Li-li
    2016, 31 (5):  822-832.  doi: 10.11849/zrzyxb.20150033
    Abstract ( )   HTML ( )   PDF (6532KB) ( )   Save
    Oasis agriculture is not only the leading industry, but also the main water-consumption industry in the Minqin Oasis. The large water consumption of farming is the chief cause of intensifying contradiction between water supply and water demand and continuous deterioration of ecological environment. The optimization of agricultural structure, especially the cropping structure, is the key of sustainable development of agriculture in the Minqin Oasis. In this paper, the impact of cropping structure adjustment on the water demand of crops in the Minqin Oasis in recent 33 years was analyzed by using the theory of virtual water and the water demand models. Three conclusions are drawn. Firstly, the planting industry structure has been experienced great changes. The areal ratio of food crops, economic crops and other crops to the total planting area was readjusted from 84∶12∶4 in 1978 to 25∶72∶3 in 2010. Due to the rapid decreasing of wheat area, the proportion of food crops decreased, while the proportion of cotton, oil crops, cucurbits, fruits and vegetables area increased during this period. Secondly, the water demand of crops increased from 2.15×108 m3 in 1978 to 2.49×108 m3 in 2010. The water demand ratio of food crops to economic crops changed from 88∶12 in 1978 to 31∶69 in 2010. Thirdly, the ecological water-saving effect of planting structures adjustment at different times in Minqin was different. From 1979 to 1998, there was no water-saving effect; during 1999-2008, planting structure adjustment showed obvious water-saving effect; during 2009-2010, there was no water-saving effect due to the increasing water demand caused by further adjustment of planting structure. The total proportion of five kinds of high water demand crops played a decisive role in the water-saving effect. These results would provide scientific basis for the cropping structure adjustment and the rational utilization of water and soil resources in the Minqin Oasis.
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    Effect of Land Use Change on Gully Erosion in Nemoer River Basin of Typical Black Soil Region of Northeast China
    WANG Wen-juan, DENG Rong-xin, ZHANG Shu-wen
    2016, 31 (5):  833-844.  doi: 10.11849/zrzyxb.20150497
    Abstract ( )   HTML ( )   PDF (6493KB) ( )   Save
    The black soil region of Northeast China is one of the most important grain-producing areas in China. However, increasingly severe gully erosion has destroyed much farmland and reduced grain production. In this paper, the typical black soil region of Northeast China which locates in the Nemoer River Basin was chosen as the study area. Based on Corona imagery in 1965 and SPOT 5 imagery in 2005, the distributions of gullies in 1965 and 2005 were obtained; based on relief maps in 1954, MSS imagery in 1975 and TM imagery in 1995 and 2005, the land use data were obtained in different years; then the effect of land use change on gully erosion was analyzed. The results revealed that the area of regions where gully density was greater than 250 m/km2 increased from 0 km2 in 1965 to 4 077.17 km2 in 2005, which accounted for 37.57% of the total eroded area. From northeast to southwest of the region, the increase of gully density changed from dramatic increase to slight increase. Gully erosion on the cultivated land was the most serious, and on the grassland and marsh was the secondary, while on the forest land was the most slight. The gully density increased the most during the interchange between cultivated land and grassland, which was 600.60 m/km2 and 456.08 m/km2, respectively. The gully density increased 346.91 m/km2 during the conversion of the forest to cultivated land. The increase proportion of cultivated land in different gully erosion zones was 29.21%-46.54%. However, the area of grassland and marsh decreased in different gully erosion zones that the proportions of decrease ranged between 27.10%-41.50% and 5.86%-12.50%, respectively.
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    Effects of Disturbance Intensity on Spatio-temporal Differentiation of Soil Particle Size in Reclamation Areas of Tidal Flat
    ZHANG Meng, PU Li-jie, WANG Xiao-han, WANG Qi-qi, YU Xue
    2016, 31 (5):  845-854.  doi: 10.11849/zrzyxb.20150629
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    Tidal flat is one of the important ecotones and ecosystems between land and sea, but tidal flat reclamation has been an important way to release the increasing pressure of land-use due to the economic development in coastal regions. We analyzed the spatio-temporal differentiation of particle size distribution (PSD) on tidal flat with different years of reclamation and different intensities of disturbance, and compared the effects from natural succession and human activities on the process of environment change in the reclaimed zones. The results demonstrated: 1) During 60 years of reclamation, with the growth of reclamation period the content of sand decreased while those of silt and clay increased under all levels disturbance, and the decreasing rate of sand could reach 0.72% per year after desalination. 2) With no disturbance, the soil PSD could reflect the physical process of tidal flat being reclaimed and separated from the sea water, while under the intense natural and artificial disturbances it would reflect the integrated effects of both factors. 3) Cultivated methods, time and soil erosion would all induced significant spatio-temporal differentiation of PSD. 4) The spatio-temporal differentiation of PSD in reclaimed zones could generally demonstrate the environmental characteristics of tidal plat, and had significance in developing land resources in reclaimed tidal flat. During the long-time reclamation of tidal flat, the key affect factors were different in different regions at different stages, which lead to many unreasonable phenomena of land use pattern and resources allocation, and caused dramatic changes and fluctuations in soil environment. The correlation between natural resources and human activities should be carefully assessed.
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    Spatial Variability of Soil Organic Matter and Appropriate Number of Samples on County Scale in Jianghan Plain
    YU Lei, WEI Dong, WANG Hui-xia, HUANG Qun, PENG Yan, XU Yuan-yuan
    2016, 31 (5):  855-863.  doi: 10.11849/zrzyxb.20150614
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    Soil organic matter (SOM) is a key index to estimate soil fertility and quality of cultivated land. Finding an appropriate number of samples on county scale is very important in saving costs while accurately expressing the spatial variability of SOM. In this research, Gong’an County, with an area of 2 258 km2, locating in the hinterland of Jianghan Plain (111°25′-111°48′E, 29°37′-30°19′N), was chosen as a typical case. A total of 4 045 soil samples were collected for analysis of SOM content. After the rejection of outliers, 3 950 sample sites were retained for further analysis. First, semi-variance function was used to explore the whole spatial variability. Then, a gradient template was defined to calculate the gradient vector, and the area was devided into seven parts based on the density of the pixels which had high gradient values. Moran’s I was used to describe the spatial variability of each part. In order to determine the appropriate number of samples, 100 points were randomly sampled and independent verification was used to validate the precision of Kriging interpolation result under different number of sample sites, i.e., 3 850, 2 695, 1 886, 1 320, 924, 647, 452 and 317. In order to improve the accuracy of sampling, a simple dichotomy method was employed to find the most appropriate number of samples. Geostatistical analysis suggested that the spatial variability of SOM distribution was moderate, and structural factors showed that SOM was affected by human activities in the research region. Six high spatially variated areas were found by gradient calculation on the basis of Kriging interpolation, and the local Moran’s I showed great anisotropy of SOM distribution and significant spatial variability in these regions, which suggested that more sampling sites are needed in these regions to obtain accurate spatial interpolation. Independent verification showed that the number of sampling points was positively correlated with the modeling accuracy and the reasonable number wasl was between 452 and 657 in this area. Finally, the appropriate sampling number was determined as 598 by dichotomy method. The results can provide guidance for monitoring and controling farmland quality in Jianghan Plain.
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    The Dynamic Changes of Grass Yield during the Growing Season in Tibetan Grasslands and the Sustainable Development Strategies
    WANG Tao, SHEN Wei-shou, LIN Nai-feng, OUYANG Yan
    2016, 31 (5):  864-874.  doi: 10.11849/zrzyxb.20150449
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    Using actual survey data of grassland yield in Tibet and NDVI data sets, grass yield estimation model in Tibet was established, and then the characteristics of spatial and temporal variation of grassland yield in the grass growing season of Tibet during the period of 1987 to 2010 were analyzed quantitatively. Research showed that: during the period from 1987 to 2010, the growth rate of grassland yield in Naqu was the largest, which was 54%. However, the grassland yield in Lasa showed a decrease of 4%. Spatially, the growth of grass yield showed a trend of increase from northwest to southeast. The areas of increased grassland yield mainly located in the north-central Tibet, while in southern region there were mostly areas of grassland yield reduction. The area of grassland with increased yield accounted for 76.04% of the total grassland area. The area of grassland with reduced yield was only 23.96% of the total grassland area. The area of grassland with increased yield was significantly larger than that of grassland with reduced yield during the period from 1996 to 2006 in Tibet. In order to improve the grassland ecosystem and the grassland yield in Tibet, this article proposed a sustainable development strategy for Tibet grassland resource from the aspects of grassland utilization, spatial pattern, pest control, and ecological compensation for returning farmland to grassland.
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    Resource Research Method
    Agricultural Productivity Estimation with MODIS-OLI Fusion Data
    NIU Zhong-en, YAN Hui-min, HUANG Mei, HU Yun-feng, CHEN Jing-qing
    2016, 31 (5):  875-885.  doi: 10.11849/zrzyxb.20150632
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    Large-scale and high-precision of agricultural productivity monitoring depends on remote sensing with high spatio-temporal resolution. Remote sensing data with high spatial resolution or temporal resolution acquired by single type of sensor cannot meet the need of clearly monitoring dynamic crop growth on farmland parcel scale. MODIS data with 250-1 000 m spatial resolutions and Landsat data with 30 m spatial resolution are generally used to monitor vegetation dynamics. To supply the gaps of low spatial resolution of MODIS data and long revisit period of Landsat data, this study used Landsat 8 OLI data with 30 m spatial resolution and MODIS data with 500 m spatial resolution and 8-day temporal resolution as data sources, and adopted data fusion technique to fuse high spatial resolution of OLI data and high temporal resolution of MODIS data. Using this technology, the time-series data with 30 m spatial resolution and 8-day temporal resolution were acquired. We took Yongning County in Ningxia as the study area, and used VPM (Vegetation Photosynthesis Model) to estimate the NPP in this area. Results show that, there was high consistency between fused vegetation indexes and OLI vegetation indexes, the determination coefficient of EVI and LSWI being 0.70 and 0.51, respectively. Fused NPP data with 30 m spatial resolution has better detailed information. This data improves the estimated accuracy of mixed pixels in MODIS images, while retains original time and process information of MODIS data. Fused NPP data was consistent with the NPP obtained with MODIS data in pixels where farmland accounted for more than 30% of the mixed pixel, meanwhile fused NPP data was significantly higher than NPP calculated form MODIS data in pixels where farmland accounted for less than 30% of the mixed pixel, since fused NPP had distinct boundaries while NPP calculated from MODIS had not. Fused NPP data show the growing of crop with 30 m spatial resolution. Compared with studies that use MODIS data with 500 m resolution and MOD17 product with 1 000 m resolution, NPP data estimated by fused data can more effectively detect the promotion of agricultural productivity generated by high standard farmland construction. The difference between regions with high standard farmland construction and the neighbors calculated with MODIS-OLI data, VPN-MODIS data and MOD17 data were 62.66, 39.87 and 2.90 g C/(m2·a), respectively.
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    Orginal Article
    Water Security Evaluation Model Based on the Logistic Curve Optimized by Particle Swarm Optimization
    SONG Pei-zheng, WANG Jia-yang, LIU Wei, YU Jing, ZHANG Bi
    2016, 31 (5):  886-893.  doi: 10.11849/zrzyxb.20150528
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    Pressure-state-response frame model was introduced to build the index system of regional water resource security quantitative assessment. The Logistic index model was used to simulate the influence of each index, and the parameters in Logistic index formula were optimized with particle swarm optimization (PSO) algorithm. Sensitivity analysis was adapted to verify the reliability of the Logistic index formula. The evaluation indexes and grades of each prefecture-level city in Anhui Province were calculated by the optimized Logistic index formula, and the sub-systems of pressure, status, and respond were evaluated as well. The main conclusions are as following: Huangshan, Chizhou, Xuancheng, Tongling, Anqing, Lu’an, and Wuhu ranked grade Ⅱ among sixteen prefecture-level cities. Ma’anshan, Hefei, Huainan, Chuzhou, Huaibei, Bengbu, Suzhou, and Bozhou ranked grade Ⅲ. Fuyang ranked grade Ⅳ as insecure water resources. Further analysis on water resources security in pressure, status, and respond sub-systems showed that indicators of pressure sub-system reflected the effect of human economic and social activities on water resources. The indexes of Tongling, Hefei, Huainan and Ma’anshan are higher, indicating that the social economic, technical level and climate condition in these four cities provide better support to regional water resources. State sub-system reflected the safe coefficient of regional water resources. The indexes of Chizhou, Huangshan and Xuancheng are higher, showing safer utilization of regional water resources. Response sub-system reflected the countermeasures of water resources issues. The index of Hefei is the highest, showing that Hefei has the highest response intensity on water resources issues. The study shows that the Logical index formula optimized by particle swarm optimization is practical and feasible for regional water security assessment, and it provides scientific basis for regional water resource planning and management.
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