The land reclamation of Xinjiang has gone through three periods since the founding of New China: 1) from 1950 to 1977, the economic activities in this region were mainly reclamation to increase the area of farmland. Although the cultivated land area increased gradually, the productivity level of agriculture and food supply was lower because of the "great leap forward" and the "ten years convulsion". In addition, importation is needed in individual year. 2) From 1978 to 1995, the economic activities in Xinjiang were mainly enhancing per unit area yield without expanding the reclaimed area, leading to substantial increase in food yield. In addition, the area of food supply was gradually reduced, area of cotton was increased, resulting in not only food self-reliance but also the establishment of a national base for cotton production. 3) From 1995 to 2009, the main economic activities in Xinjiang were to enhance the unit yield together with enlarging the reclaimed area, the yield of food and cotton increased further to a large degree and unit yield of food was higher than the national average level, hence the biggest cotton producing area was set up with the total yield accounting for half of the whole nation. Although great achievements have been gained in land reclamation in Xinjiang in the past 60 years, yet ecological environment was seriously damaged and the existing cultivated land has reached the carrying capacity of the water resource. It is suggested no land reclamation should be done, but land conformity should be carried out, so as to raise the coefficient of net land use, and develop water-saving irrigation to enhance land productivity.
The paper gives a brief review about the empirical studies that have been conducted on property price gradients. Based on the classic urban monocentric model, the urban land leasing price-distance relationship is estimated with the aids of the hedonic price model. It is shown that both commercial and residential land price gradients become flattening from 2005 to 2011. It indicates the suburban expanded trends of construction land in metropolitan Beijing. The residential land price curve took a reverse trend since 2009, which violates the traditional monocentric bit-rent curve. The reason lies in two aspects: firstly, not all the residential land parcels are leased through open auction or tender; secondly, there are influential sub-centers in the outskirts of Beijing. Contrary to the residential land, the commercial land price curve fits the negative gradients well during the time. A floor-distance linear regression model is built to explore the change of land development intensity from urban core to urban fringe. The negative floor-distance coefficients of commercial land are captured which demonstrates the land development intensity is decreasing from urban center, but it is flattening during the time. The coefficients of residential land are not significant, illustrating linear regression model does not fit well. As the choice of functional form may result in inefficiency of estimation, a nonparametric analysis is proposed. The advantage of nonparametric estimation is that no priori assumptions on the urban spatial structure and functional form are required, so it is more flexible than the parametric estimations. The results show that the new method reveals more reasonable information about residential land price curve and floor-distance curve in metropolitan Beijing.
Considering the energy security and greenhouse gas emissions, many governments have been developing bio-liquid fuel industry in recent years. Chinese government also advocates to develop fuel ethanol industry with non-food crops such as cassava. However, scientists have been debating heatedly on carbon emission of bio-liquid fuels. The focuses are the destruction of soil carbon pool during cassava plantation and the use of by-product during processing in different technical conditions. This paper builds the carbon balance analysis model, then, assesses the carbon emission of cassava fuel ethanol in its life cycle. The results show the carbon emission of cassava fuel ethanol per kilogram in its life cycle is 0.457 kg and 0.647 kg respectively in the new and old technical conditions. Carbon emission mainly comes from the use of nitrogen fertilizer, the destruction of soil carbon pool and the fossil energy input of cassava processing, the three parts are 9%, 29% and 50% of total emission respectively in the new technical condition. Taking gasoline as a reference, in old technical condition, the carbon emission of cassava fuel ethanol is negative benefit. But in new technical condition, the carbon emission of cassava fuel ethanol is 90% of gasoline carbon emission. This percentage will drop to 64% if the destruction of the soil carbon pool was avoided. Therefore, in order to promote the development of China’s cassava fuel ethanol, first, farmers should be guided to apply fertilizer properly, grow cassava on marginal land, not convert woodland, grassland and other types of land use patterns. In addition, we should exploit efficient fuel ethanol conversion technologies and strengthen the use of by-product meanwhile.
Increasing production capacity, the core of the agricultural land consolidation, has risen to one of the most important strategies at the national level. Agricultural land consolidation is a comprehensive engineering including the land plots merging, reconstruction of farmland irrigation and drainage facilities as well as road system to improve the engineering and ecological shelterbelt. Agricultural land consolidation project implementation measures would inevitably lead to changes in land use characteristics of the project area, which directly led to changes in cropland production capacity.Hubei Province as the study area can be roughly divided into three different agricultural land consolidation regions, such as plain, hill and mountain, and the different types of land regions have different production abilities of agricultural land. Through the establishment of agricultural land consolidation affected production ability of agricultural land estimation model, the effect of the different types of plain, hill and mountain land consolidation on the production ability of agricultural land in Hubei Province was quantitatively evaluated, the results indicate that: 1) Different types of agricultural land have a positive impact on the production ability of agricultural land, mountains remediation of the production ability of agricultural land increased by 168.91%, hill increased by 57.78% and plain increased by 38.32%. 2) Agricultural land consolidation infrastructure elements of different types of land affected the production ability of agricultural land differently, plain remediation district infrastructure elements increased the maximum, being 78.62%; hill remediation of water resources elements increased the maximum, being 75.00%; mountain remediation infrastructure elements increased the maximum, being 199.12%. 3) In different agricultural land consolidation regions, the contribution rate of infrastructure elements in the production ability of agricultural land is the largest, and that of plots merge is the smallest. It is suggested that funding delivery of the national land consolidation and delineation of the key areas should be appropriate to increase the importance of the mountains and hill remediation, the project area should reasonably support the scattered village renovation projects, and try to avoid the ecological loss.
Based on the MODIS NDVI data, growing season NDVI spatiotemporal change was analyzed and relationships between NDVI and temperature, precipitation were also explored for typical steppe, meadow steppe and desert steppe in Inner Mongolia during 2000-2010. The results indicated that growing season NDVI was increased by 0.735% a-1 in Inner Mongolia grassland. Typical steppe has significantly increased from 2000 to 2010 (1.063% a-1). However, NDVI showed decreased trend in part areas, which accounted for 31.807% of the study area. Decreasing areas are 8.664×104, 6.814×104, 2.841×104 km2 for typical steppe, meadow steppe and desert steppe, respectively. Most of the grasslands excluding meadow steppe had a higher correlation with precipitation than temperature. Correlations between NDVI and temperature and precipitation had the similar trend: meadow steppe>typical steppe>desert steppe. In addition, the result also shows that responses of the grassland to temperature and precipitation changes have a conspicuous lag effect and the lag times have obvious longitude and latitude characteristics with increasing longitude and latitude.
The reference crop evapotranspiration (ET0) in the eastern plateau agricultural region of Qinghai Province was calculated by Penman-Monteith formula based on meteorological data of seven meteorological observation stations. The main change circle as well as the main trend of main meteorological elements were analyzed with Multi-Taper Method (MTM). Sensitivity coefficient of temperature, sunshine duration, relative humidity, wind speed sensitivity in growing season of eastern Qinghai were studied based on partial derivatives. The results showed that the seven stations we used have a constant 19.23－22.22-year changing cycle, temperature (including maximum temperature, minimum temperature and average temperature) showed a significant upward trend in the whole region. Sunshine duration, wind speed and relative humidity differed with the variation of latitude. In south of latitude 36°, sunshine duration and wind speed showed a significant upward trend while relative humidity decreased, the other five stations in north of latitude 36° had an opposite trend; that sunshine duration was the most sensitive variable to ET0 in general for the region, followed by air temperature and relative humidity, wind speed had the least impact.Sensitivity coefficient in the whole growth season changed with meteorological factors. The sensitivity coefficient of sunshine duration in the whole growth season fluctuate insignificantly, the maximum value appeared in April, and the minimum value appeared in September. The sensitivity coefficient of temperature varies in a single curve and the maximum value appeared in July. The sensitivity coefficient of wind speed varies in a single valley and the minimum value appeared in July.
Tarim River riparian forest is highly prized in the Tarim Basin for its great ecological, economic and social benefits. This paper, based on remote sensing images and GIS technology in combination with field survey and the methods of buffer analysis, studies the spatial distribution characteristics of the existing forest. The result shows that: 1) the area of desert riparian forest is 58.42×104 hm2(14.07% of the total). The area of desert riparian forest from upper to lower reaches of the Tarim River accounted for 2.94%, 3.75%, 3.95%, 1.99% and 1.44%, respectively, the width and abundance of desert riparian forest of north bank is larger than that of south bank, where the uneven time and space distribution of water resources is the main cause for the desert riparian forest distribution characteristics. 2) Desert riparian forest is mostly distributed following the channel terrain and decreases with the distance further away from the bank. The runoff has obvious effect on the desert riparian forest recovery which is close to the Tarim River and has less effect on the desert riparian forest recovery which is farther away from the Tarim River. The sphere of influence of the river is 38.33-45.51 km on the north bank and 15.21-39.33 km on the south bank. 3) The rate of forest area in the basin is not high and shows an uneven distribution in the Tarim River. The desert riparian forest is in zonal distribution centering around the river with the distribution range of 10-80 km, the important protection range of 0.8-12.3 km, the recovery range of 2.2-24.5 km and the reconstruction range of 4.7-30.1 km. According to the distribution characteristics of the desert riparian forest and conservation goals, unified planning and coordination of water resources utilization is an effective ecological management measure suitable to local conditions.
The paper analyzed the precipitation spatio-temporal distribution in Beijiang River Basin of Guangdong Province based on monthly and annual data of 18 stations from 1965 to 2007. The non-parametric method of Mann-Kendall is applied, and the result shows that precipitation of the whole basin has an insignificant upward trend from 1965 to 2007. The result of the moving t-test indicates that the increasing change points of precipitation appeared in 1992 and 1993. The basin was divided into four different subareas by REOF method. The paper selected subareas of characteristic vector of the largest load site as the benchmark station, and analyzed the cycle characteristics and the relationship between the precipitation and SST in Niño 3 by the continuous wavelet transform, cross wavelet and wavelet coherence techniques. The results show that monthly precipitation of four stations have significant correlation with SST in Niño 3. The time-lag correlation analysis shows that there is the strongest correlation between monthly precipitation and SST in Niño 3 at later 3 and 4 months in Nanxiong, Fogang and Liannan stations, but Sanshui station at the same time. This difference may because that Sanshui area had the influence of human activity more intense than others.
By connecting temperature and precipitation data of seven national standard meteorological stations which were evenly distributed in Hainan Island from 1959 to 2008 with the existing climatic regionalization of Hainan Island, we studied climate change of different climatic regions in Hainan Island in the last 50 years. And the result showed that the trend of temperature increase obviously existed in these regions in the last 50 years, with warming amplitudes being higher in Northeast, Southwest, Central Mountain, Southeast and Northwest regions, respectively. In interannual time scale, the warming amplitudes of annual average maximum temperature (Tmax), annual mean temperature (Tmean) and annual average minimum temperature (Tmin) were decreasing from Tmin to Tmax. In seasonal time scale, the annual mean temperature (Tmean) was increasing seasonally in different regions, with warming amplitudes being higher in winter, autumn, spring and summer, respectively. The seasonal warming amplitudes of geographic differences were similar to those in interannual time scale. What’s more, the abrupt change of Tmean was changeable in different climatic regions, being 1972-1974 in Southwest, 1979 in Northwest, 1987 in Northeast, 1985-1990 in Southeast, and 1990 in Central Mountain regions, respectively. And the annual average precipitations were changeable in different climatic regions which were higher in Central Mountain regions, then decreasing in the order of Southeast, Northwest, Northeast and Southwest. On the other hand, the annual precipitation anomaly and abrupt change of all climatic regions fluctuated sharply except Southwest region which got through the significance test (P<0.05). Generally, percentages of dry/wet seasonal precipitation accounted for 20% and 80% respectively in annual precipitation in different climatic regions. Light rainfall mainly occurred in dry season while heavy rainfall mainly in wet season. And the contribution rate of precipitation in dry season is the highest in Central Mountain region while in wet season it was the contrary. The precipitation levels of heavy rain and rainstorm had great influence on annual precipitation, which accounted for about 50% of total precipitation. And Southwest region was the heavy rainstorm and extremely heavy rainstorm-prone area.
Urban settlement climate comfortability is human’s direct response of the weather condition. China’s northern coastal region has long been considered as one of the best living comfort climate regions. This paper evaluates the human settlement climate comfortability of Liaoning coastal cities based on the analysis of the basic climate change characteristics from 1951 to 2010, and evaluates urban human settlement climate comfortability of Liaoning coastal cities by the method of human comfort index, R/S and correlation analysis. The results showed: 1) Temperature change presents a warming trend at a rate of 0.311℃/10 a, which is consistent with global temperature change characteristics; precipitation, wind speed and relative humidity show a downward trend, being -12.795 mm/10 a, -0.193 m/s/10 a and -0.678%/10 a; the meteorological elements in the period 1960-1980 had evident mutations. 2) The settlement climate comfortability in Liaoning coastal cities is good over the past 60 years, the BCMI showed a clear upward trend during 1951 to 2010, which is consistent with global warming. Most people feel comfortable from April to October, and the most comfortable months are from June to September. Dalian is the city with best settlement climate comfortability in Liaoning coastal region. 3) The correlation analysis found that the temperature and wind speed are the most important factors affecting climate comfortability. By R/S analysis, it was found that the Hurst values of most elements were greater than 0.5, indicating that in the future temperature will continue to raise, precipitation, wind speed and relative humidity will maintain the current decreasing trend, the BCMI in Liaoning costal cities will increase too. According to interaction among urban development, climate change and habitat climate comfortability, we should respond to the global climate change actively and reduce the impact of human activities on climate.
Hydrological characteristic variation is a main content in hydrological research. Hydrological characteristic variation includes not only the concept of time and space, but also includes concept of attribute. Study of hydrological sequence in attribute, spatial and temporal variation can reflect the true situation of hydrological characteristic variation all around. This paper discusses the connotation of hydrological variation, and puts forward the measurement of hydrological characteristic variation in attribute category, time domain and space domain. An example was given based on the runoff and rainfall series of Beijiang River Basin to reveal the hydrological variation characteristics from attribute category and the space-time category comprehensively. The calculation shows that the runoff series of 1992-2006 and 1973-2006 all varied in contrast with 1992-2006; from spatial analysis, the gravity center model shows that the rainfall has changed in direction in 1959, 1967, 1975 and 1983 from the moving direction of gravity center, and the years that the gravity center moved far away to the average value were 1967, 1975, 1983 and 2000 from the moving distance of gravity center.
With the vulnerable ecological environment of sea islands, protecting the ecosystem of islands as well as their surrounding waters, reasonably exploiting and utilizing the natural resource of sea islands, and promoting the sustainable development of island economy and society have become basic purpose of Legislation of Sea Island Protection of PRC. This essay attempts to refer to the idea of land area sustainable development index system, select indexes in terms of four aspects including survival support, ecological environment, economic development, social and intellectual support, integrating the natural environment of islands and the particularity of society and economy, determine the weight of evaluation index of island sustainable development with the integration of entropy weight method and the nonstructural decision fuzzy set theory model, and build the index system of island sustainable development; the essay also further imports variable fuzzy evaluation method of the unity of the opposites and quality interaction law, set up the comprehensive evaluation model of island sustainable development based on the theory of variable fuzzy set, evaluate and verify the condition of sustainable development in Changhai County from 2001 to 2011, and identify key factors, existing problems and restrictive factors affecting the capability of sustainable development. This provides scientific analyst data for improving the level of sustainable development of economy and society.
A comprehensive survey of water quality and quantity and aquatic biological resources was conducted in Ulungur Lake in 2008, and then, the basic data about water quality and quantity were obtained. On this basis, a preliminary analysis was carried out on lake environmental change in the last 60 years. According to the changes of regional climate and human activity patterns, the Ulungur Lake environmental change can be divided into four periods. In the first period before 1956, Ulungur Lake was in the natural state with Ulungur River as the main supply, and its water fluctuation was controlled by the climate change. The second period was from 1956 to 1970 with the rapid increase in intensity of human activities. Because of the lake input amount reduction induced by water consumption of the drainage exploitation, there had been a steady decline in the lake water level. The period from 1970 to 1995 was the third stage in lake environmental change. Besides the water consumption in the drainage area exploitation, the water level fluctuation was also related to other human activities such as digging canals and building dams during this period of time. In the fourth period since 1995, because water conservancy projects ran smoothly and regional climate was suitable, the lake environmental change was relatively stable. Recently, the runoff of Ulungur River decreased rapidly and even had a zero flow due to the arid climate, which caused Ulungur Lake water to flow back into Jili Lake, and aggravated lake water environmental degeneration and catchment’s desertification. The results indicate, apart from the increase in river inflow, maintaining the lake water environment a stable state in the 1990s depends largely on scientific evaluation and optimizing regulation of industrial and agricultural water consumption at the present climate condition.
In Henan Province, non-biogas farmers and biogas ones from nine towns distributed throughout nine counties had been chosen as examples, from which the soil, surface runoff and indoor air quality were monitored. Specifically, the comparative study upon the effect of household biogas pond construction on improvement of rural ecological environment was analyzed quantitatively. The results showed that contents of organic matter, total nitrogen, available phosphorus, and available potassium in soil samples of non-biogas rural households obviously were lower than that of biogas ones, and the contents of four nutrition compounds in the soil in the four-in-one ecological model were much higher than in the three-in-one ecological model. The average concentrations of NH3-N, TP and COD in surface runoff of non-biogas samples were higher than that of biogas ones. The average concentrations of indoor air pollution including SO2, CO, PM10 and NH3 of biogas samples were much lower than that of the non-biogas ones. In addition, the concentrations of these four indoor air pollutants changed with the seasons. Lastly, it could be concluded that rural biogas pond construction would enrich the soil, reduce area-source pollution and improve the rural residential environment. It is of a great significance to energy-saving and emission-reduction.
The precipitation in mountains is the main source of surface water and the beginning of water cycle in an inland river basin, where the shortage of water resource is a restricting factor for ecological balance and socio-economic development. However, terrain complexity and scarcity of meteorological stations in mountains make the precise estimation of spatio-temporal precipitation distribution in mountainous regions a difficult problem in the field of hydrology and ecology. Fortunately, the multi-satellite precipitation analysis (TMPA) product from the Tropical Rainfall Measuring Mission (TRMM) and statistical downscaling models can provide an effective solution for this issue.
Heihe River is the second largest inland river in arid-semiarid regions of China, where the water resource of Heihe River Basin is important for sustainable development of natural environment and social economics in arid and semi-arid regions. This paper firstly used Digital Elevation Model and multivariate regression model to make an attempt for statistical downscaling of the TRMM 3B42 products obtained from 2000 to 2009. The downscaled results were tested using observed data. Secondly, the high-resolution downscaled data was used to analyze the spatio-temporal variation of precipitation at upper reaches (mountainous regions) of Heihe River from 2000 and 2009. Results show that: 1) Compared with the original TRMM data, the downscaled data with high resolution could capture more details about variation and trends of precipitation; 2) the effect of slope aspect on precipitation indicates that precipitation in east aspect is more than west aspect with the largest value reaching 10% in east-west direction, while there is no significant difference in south-north direction; 3) during the last decade, the mean annual precipitation was 344 mm/a in the upper reaches of Heihe River, and ranged from 250-400 mm/a in most regions; 4) the precipitation has the positive relationship with elevation below 3800 m, even the mean precipitation has a slight decrease, the largest precipitation zone exists in the zones with elevation greater than 3800 m; 5) the precipitation in the upper reaches of Heihe River followed a gradual decreasing trend from southeast to northwest, however, with different decreased amounts in different months; and 6) the precipitation took place mainly from June to September and was relatively scarce in winter and spring.
In order to address the unsustainable use of global freshwater resources, indicators are needed which make the impacts of humans’ activity on water resources transparent. In this study, a life cycle assessment (LCA)-based water footprinting method is introduced and demonstrated for a case study product of wheat produced in China. Comparing with existing virtual water-based water footprint calculation, the LCA-based method enables meaningful comparisons between products, production stages and production places in terms of their potential environmental impact. The case study shows that the average water footprint of wheat produced in Huanghe and Haihe drainage basins is 1262 L H2Oe·kg-1 while that of wheat produced in Changjiang drainage basin is only 31 L H2Oe·kg-1. It is indicated that wheat production exerts much more pressure on water resources in the water-scarce north than in the water-rich south. This LCA-based water footprinting method could provide scientific basis to guide strategic decisions for China’s food production and sustainable water resources use.
This experiment was conducted at Fukang Station of Desert Ecology of Chinese Academy of Science located in the southern part of Gurbantunggut Desert, and ground penetrating radar (GPR) is used as the main data acquisition tool. Combined the character of the two measurement methods of ground penetrating radar, a determination method of optimal fixed offset is presented and the goal of fast estimating soil water content can be achieved. The result showed that: 1.9 m was determined as the optimal fixed offset by fixed offset measurement, the ground wave of this fixed offset was picked and soil water content was calculated, and the estimating water content at 30.5 m on survey line is compared with the result of Time Domain Reflectometry, 20 cm is the effective detecting depth for GPR ground wave to estimate the soil water content in the experimental site, and deviation is only 0.015 m3/m3, the accuracy can meet the actual demand, the average water content of the upper sandy showed spatial heterogeneity from 0 to 36.5 m on survey line. This method can estimate mesoscale soil water content fast and accurately, which can provide a scientific basis for agricultural production and crop irrigation.
