The integration of rivers and basins highly implies the possible existence of certain relationships between hierarchical characteristics of river networks and primary basin factors.Here we investigated river networks ...The integration of rivers and basins highly implies the possible existence of certain relationships between hierarchical characteristics of river networks and primary basin factors.Here we investigated river networks in two large basins,the Yangtze River and the Yellow River,characterized with basic factors such as annual precipitation,slope,soil erodibility and vegetation.Hierarchical analysis demonstrated a fair self-similarity of river networks at the stream-order 1-5 in both rivers,described by the structural parameters including bifurcation ratio,side-branching ratio,drainage density,and length of headwater-river.Besides precipitation,basin slope was essential in shaping river networks in both basins,showing a significant positive correlation(R^2=0.39-0.85)to bifurcation ratio,side-branching ratio,and drainage density.Given the same basin slope(5°-15°),the higher soil erodibility and sparse vegetation would promote greater side-branching ratio and drainage density in the Yellow River,which were estimated 11.97%and 63.70%larger,respectively than those in the Yangtze River.This study highlights the importance to formulate basin-specific strategies for water and soil conservation in terms of different structures of river networks.展开更多
Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River...Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River in relation to natural and human factors in the drainage basin, such as the annual precipitation in different water and sediment source areas, proportion of >0.05 mm sediment of the total sediment load to the lower reaches of Yellow River, the regu-lated degree of the “clear” baseflow from the drainage area above Lanzhou, frequency of hy-perconcentrated flows, area of soil and water conservation measures in the drainage basin. As a result, a multiple regression equation has been established between Fs and 7 influencing factors, with multiple correlation coefficient r = 0.90. The reduction in annual precipitation in different water and sediment source areas has different effects on Fs. The reduction in annual precipitation in the area above Hekou Town and the area between Longmen and Sanmenxia results in a reduction in Fs, but the reduction in annual pre-cipitation in the area between Hekou Town and Longmen results in an increase in Fs. The grain size composition of sediment load strongly affects the Fs; the larger the proportion of >0.05 mm sediment in the suspended sediment load entering the lower reaches of the Yellow River is, the lower the Fs will be. Thus, if the Xiaolangdi Reservoir traps coarse sediment and releases fine sediment, Fs will be enhanced. This study also shows that the lower the proportion of high-flow season river flow to the annual total river flow at Lanzhou Station is, the lower the Fs will be. Therefore, the interception of large quantities of clear water by the reservoirs on the upper reaches of Yellow River is one of the major causes for the decrease in Fs in the lower reaches of the Yellow River.展开更多
In the eastern Ordos basin, due to the diversity of the tectonic setting, coal rank, gas content and permeability, coal reservoirs have differing characteristics. In this paper, based on coal reservoir geometry, gas c...In the eastern Ordos basin, due to the diversity of the tectonic setting, coal rank, gas content and permeability, coal reservoirs have differing characteristics. In this paper, based on coal reservoir geometry, gas content, adsorption capacity, pores and fissures developments and permeability data, the coalbed methane(CBM) reservoir characteristics and their controlling factors in the eastern Ordos basin is discussed. The results show that, due to undergoing different paleo-temperatures in the geological history,coal rank has a higher trend from the north part to the south and from the shallow part to the inward basin, which determines CBM distribution and recoverability. In the north, although having large coal thickness and high permeability, Zhungeer-Xingxian coal rank is low, and gas content is small. In the central part, with medium rank, higher gas content and relatively high permeability, and the Wubao-Liulin area is the most favorable area in the eastern Ordos basin. In the southern part, medium and high metamorphism coal occurs, and although having the highest gas content, the permeability in the Hancheng area is low due to the development of sheared coal.展开更多
A clear understanding of the relationships among multiple ecosystem services(ESs) is the foundation for sustainable urban ecosystem management. Quantitatively identifying the factors that influence ES trade-offs and s...A clear understanding of the relationships among multiple ecosystem services(ESs) is the foundation for sustainable urban ecosystem management. Quantitatively identifying the factors that influence ES trade-offs and synergies can contribute to deepening ES research, from knowledge building to decision making. This study simulated soil conservation, water yield and carbon sequestration in Beijing, China, from 2015–2018. The spatial trade-offs and synergies of these three ESs within the five major river basins in Beijing were explored using geographically weighted regression. Furthermore, geographical detector was applied to quantitatively identify the driving mechanism of the environmental factors for the ES trade-offs and synergies. The results show the following:(1) the spatial relationships between soil conservation and water yield, as well as between water yield and carbon sequestration, were mainly trade-offs. There was a spatial synergy between soil conservation and carbon sequestration.(2) Regarding the spatial trade-off/synergy between soil conservation and water yield in Beijing, the dominant influencing factor was temperature/elevation, and the dominant interactions of the spatial trade-off and synergy between these two ESs in Beijing and the Chaobai River Basin are all manifested in the superposition of precipitation and potential evapotranspiration, temperature, and elevation.(3) Topographic factors were the dominant factors influencing the spatial relationship between soil conservation and carbon sequestration in Beijing and its five major river basins. As a result of the distribution of water systems and hydrological characteristics of the basins, differences were observed in the effects of different combinations of interaction factors on the spatial relationship between these two ESs in different basins.(4) Temperature had the strongest explanatory power in terms of the spatial trade-offs and synergies between water yield and carbon sequestration. The interactions between precipitation and temperature and between precipitation and elevation were the dominant interactions affecting the spatial relationship between water yield and carbon sequestration in Beijing. Overall, the explanatory power of influencing factors on the trade-offs and synergies and the degree of interaction between factors coexist in different basins with consistency and differences. Therefore, understanding the quantitative characteristics of basin-scale spatial trade-offs and synergies between ESs is important for ecosystem management and the promotion of synergy in different basins.展开更多
On the basis of daily meteorological data from 15 meteorological stations in the Heihe River Basin （HRB） during the period from 1959 to 2012, long-term trends of reference evapotranspiration （ET0） and key meteorol...On the basis of daily meteorological data from 15 meteorological stations in the Heihe River Basin （HRB） during the period from 1959 to 2012, long-term trends of reference evapotranspiration （ET0） and key meteorological factors that affect ET0 were analyzed using the Mann- Kendall test. The evaporation paradox was also investigated at 15 meteorological stations. In order to explore the contribution of key meteo- rological factors to the temporal variation of ET0, a sensitivity coefficient method was employed in this study. The results show that： （1） mean annual air temperature significantly increased at all 15 meteorological stations, while the mean annual ET0 decreased at most of sites; （2） the evaporation paradox did exist in the HRB, while the evaporation paradox was not continuous in space and time; and （3） relative humidity was the most sensitive meteorological factor with regard to the temporal variation of ET0 in the HRB, followed by wind speed, air temperature, and solar radiation. Air temperature and solar radiation contributed most to the temporal variation of ETo in the upper reaches; solar radiation and wind speed were the determining factors for the temporal variation of ET0 in the middle-lower reaches.展开更多
This paper studies the distribution features, the chemical elements beyond standards and the influencing factors of shallow groundwater quality in the Guanzhong Basin through the data monitored in the last twenty year...This paper studies the distribution features, the chemical elements beyond standards and the influencing factors of shallow groundwater quality in the Guanzhong Basin through the data monitored in the last twenty years. The final purpose is to comprehensively evaluate the divisions of groundwater quality in the Guanzhong Basin. Results show that, the groundwater quality is in good shape, and suitable for drinking. Drinking accounts for 16.02% of the total, most of which are distributed in the lubotan of Weibei. Some come from loess plateau of Qian-Liquan County and some are generated by the industrial pollution of Xingping City. Materials exceeding standards include chloride, sulfate, three nitrogen, fluoride, manganese, iron, hexavalent chromium and so on. The main factors influencing the quality of shallow groundwater include groundwater exploitation, natural background value of special components and precipitation, among which the groundwater exploitation poses the greatest impact. The depth of water is positively correlated with the concentration of sulfate, nitrate and total hardness.展开更多
Significant differential hydrocarbon enrichment occurs in depressions in a petroliferous basin.There are multiple depressions in the Bohai Bay Basin, and each depression as a relatively independent unit of hydrocarbon...Significant differential hydrocarbon enrichment occurs in depressions in a petroliferous basin.There are multiple depressions in the Bohai Bay Basin, and each depression as a relatively independent unit of hydrocarbon generation, migration and accumulation, contains significantly different hydrocarbon generation conditions and enrichment degree. On the basis of previous documents and a large number of statistical data, this work comparatively analyzed the differential hydrocarbon enrichment and its major controlling factors in depressions of the Bohai Bay Basin. The results show that depressions in the Bohai Bay Basin have various hydrocarbon enrichment degrees, and can be categorized into four types, namely enormously oil-rich, oil-rich, oily and oil-poor depressions. In general, the enormously oil-rich and oil-rich depressions are distributed in the eastern part of the basin along the Tan-Lu and Lan-Liao faults, whereas depressions in the western part of the basin are poor in hydrocarbons. Moreover, the vertical distribution of hydrocarbons is also highly heterogeneous, with Pre-Paleogene strata rich in hydrocarbons in the northern and western depressions, Paleogene strata rich in hydrocarbons in the entire basin, and Neogene strata rich in hydrocarbons in the off-shore areas of the Bohai Bay Basin. From early depressions in onshore areas to the late depressions in offshore areas of the Bohai Bay Basin, the source rocks and source-reservoir-cap rock assemblages gradually become younger and shallower, and the hydrocarbon resource abundance gradually increases. Hydrocarbon supplying condition is the key factor constraining the hydrocarbon enrichment for different depressions,while the main source-reservoir-cap rock assemblage, sufficient hydrocarbons and the transportation capacity of faults control the vertical distribution of hydrocarbons. The main factors controlling hydrocarbon enrichment are different for different layers. The hydrocarbon supplying condition of source rocks is the key controlling factor, whereas the source-reservoir configuration, the main sourcereservoir-cap rock assemblages, and the fault transportation are the main factors of hydrocarbon enrichment in the Paleogene, Paleogene and Neogene, respectively.展开更多
ABSTRACT： Tabei （塔北） uplift is an area with the highest hydrocarbon enrichment in Tarim basin, and large oilfields have been found on Akekule （阿克库勒） arch at the middle section of Tabei uplift, with Ordovici...ABSTRACT： Tabei （塔北） uplift is an area with the highest hydrocarbon enrichment in Tarim basin, and large oilfields have been found on Akekule （阿克库勒） arch at the middle section of Tabei uplift, with Ordovician carbonate reservoirs. Storage space of the Ordovician carbonate reservoirs in the Akekule arch are mainly caves, pores and fractures resulted from dissolution and/or karstification. The Ordovician carbonate reservoirs are affected and modified by the diagenetie process in penecontemporaneous, epigenetic and burial periods and the multi-stage karstification related with deep hydrothermal activities, among which the most significant effect is from the meteoric water karstification related to the tectonic uplift from the end of Middle Ordovician to the end of Late Ordovician （end of O2-end of 03） and at the end of Middle Devonian （end of D2）. Varied palacogeologic settings and tectonic features at different geologic periods lead to different fluid flowing patterns, karstification mechanisms and transformation features in different regions, which further influence the reservoir distribution. The paleo-uplifts at different periods, such as end of O2-end of 03 and end of D2, control the dominant development zones of karstification; the paleogeomorphology and faults resulted from tectonic uplift control the flowing depth of the karst fluid; and the lithology controls the position and extent of karst development.展开更多
The earliest agricultural activities in Sichuan Basin can be traced hack to the middle Neolithic Age. hang the development process afterwards, the on and ha dynasties, the Sui and Tang dynasties, and the Northern Song...The earliest agricultural activities in Sichuan Basin can be traced hack to the middle Neolithic Age. hang the development process afterwards, the on and ha dynasties, the Sui and Tang dynasties, and the Northern Song Dynasty were three peaks of agricultural development. The various natural conditions resulted in a variety of agriculrural Patterns in Sichuan Basin. The drainage system Played a major role and always went before land and agricultural development in different historical periods. The wars and natural disasters in the end of the Ming Dynasty severely damaged the agricultural system. It was until the early and middle Qing Dynasty that many immigrants fm other provinces restored and promoted the agricultural activities in Sichuan Basin.展开更多
The multi-factor recombination and processes superimposition model for hydrocarbon accumulation is put forward in view of the hydrocarbon geological characteristics of multiple episodes of structural evolution, multip...The multi-factor recombination and processes superimposition model for hydrocarbon accumulation is put forward in view of the hydrocarbon geological characteristics of multiple episodes of structural evolution, multiple sets of source-reservoir-seal assemblage, multiple cycles of hydrocarbon accumulation and multiple episodes of readjustment and reconstruction in the complex superimposed basins in China. It is a system including theories and methods that can help to predict favorable exploration regions. According to this model, the basic discipline for hydrocarbon generation, evolution and distribution in the superimposed basins can be summarized in multi-factor recombination, processes superimposition, multiple stages of oil filling and latest stage preservation. With the Silurian of the Tarim basin as an example, based on the reconstruction of the evolution history of the four factors （paleo-anticline, source rock, regional cap rock and kinematic equilibrium belt） controlling hydrocarbon accumulation, this model was adopted to predict favorable hydrocarbon accumulation areas and favorable exploration regions following structural destruction in three stages of oil filling, to provide guidance for further exploration ofoil and gas in the Silurian of the Tarim basin.展开更多
Objective: In this study, the influence and response relationship between the seasonal freezing-thawing process of soil and the spatial factor changes in the management and utilization of water resource processes were...Objective: In this study, the influence and response relationship between the seasonal freezing-thawing process of soil and the spatial factor changes in the management and utilization of water resource processes were explored. Methods: The monitoring equipment in this study was arranged at different altitudes, gradients, and slope directions, such as the typical forest sample area in the Dayekou Basin of the Qilian Mountains. The spatial variation characteristics of the seasonal freezing-thawing process of the soil were analyzed, and a regression model was established. Results: 1) The results of this study determined that the rate of the soil’s freezing increased with the altitude in a trend of volatility. However, the rate of the thawing of the frozen soil was found to have an opposite trend. The variation degree of the freezing-thawing process increased with the altitude in a trend of volatility. The end time of the approximate soil freezing with altitude increased in a volatility trend ahead of schedule. However, the opposite was observed in the thawing rate of the frozen soil;2) The rate of the soil’s freezing under the mosses of the spruce forest at an altitude of 3028 m was found to be the lowest. However, in the sub-alpine scrub forest at an altitude of 3300 m, a maximum in the spatial ordering was observed, with an average of 1.9 cm·d-1. The thawing rate of the frozen soil in scrub-spruce forest at an altitude of 3300 m was found to be minimal. However, in the sunny slope grassland at an altitude of 2946 m, a maximum in the spatial ordering was observed, with an average of 1.5 cm·d-1. In the spatial ordering of the variation degree of the process of freezing-thawing with an average of 1.2, the scrub-grassland at an altitude of 2518 m was found to be the lowest, and the scrub-spruce forest at an altitude of 3195 m was also low;3) The soil freezing began on approximately October 20th, and the rate of soil freezing gradually became reduced. The arrival time of the frozen soil of up to 150 cm in depth in sub-alpine scrub forest was first observed at an altitude of 3028 m. However, the scrub-spruce forest at an altitude of 3100 m did not become frozen until approximately January 12th on average. Then, the thawing rate of the frozen soil increased gradually. The end time of the thawing was earliest observed in the sunny slope grassland at an altitude of 2946 m. However, the scrub-spruce forest at an altitude of 3100 m was found to be the last to thaw, and averaged approximately July 27th. The average durations of the freezing and thawing of the soil were 77 and 121 days, respectively, and the average duration of the entire process of freezing-thawing was 199 days;4) This study’s established regression models of the duration time of frozen soil’s thaw, and the rate of frozen soil’s thaw, all passed the R test of goodness of fit, F test of variance, and t test. Conclusions: The characteristics of the seasonal freezing-thawing process of the soil with the spatial changes were seasonal. However, the characteristics under the different spatial factor influences were not the same.展开更多
[Objective] The change rules of Lycium barbarum and meteorological factors in Qaidam Basin were studied. [Method] Botanical characteristics,growth characteristics and physiological factor changes of Ningqi 1 were anal...[Objective] The change rules of Lycium barbarum and meteorological factors in Qaidam Basin were studied. [Method] Botanical characteristics,growth characteristics and physiological factor changes of Ningqi 1 were analyzed,and the change laws of Ningqi 1 and environmental factors(including sunlight,temperature,water and soil) were investigated by using meteorological observation data in 1973-2008. [Results] The results showed that Ningqi 1 belonged to light preferring plant,and the higher photosynthetic rate showed double peak type with the peaks appearing at 12:00 and 16:00,having midday depression of photosynthesis. The diurnal variation of transpiration rate in leaves showed a double peak,and the temperature around leaves was 0.2-0.5 ℃ higher than that in the field. The average relative humidity and temperature were the key factors to affect forming L. barbarum fruits. The suitable temperature for developing big seeds was 18 ℃. [Conclusions] Ningqi 1 could be taken as the first choice variety to plant and popularize in Qaidam Basin.展开更多
The Paleogene and Neogene oil and gas in the western Qaidam basin have a regular distribution in three concentric zones from the edge to the center of the basin. Natural gas mainly occurs in the inner zone, and the ga...The Paleogene and Neogene oil and gas in the western Qaidam basin have a regular distribution in three concentric zones from the edge to the center of the basin. Natural gas mainly occurs in the inner zone, and the gas-oil ratio of the northern area of the basin is significantly higher than that of the southern area. Large amounts of carbon isotope data of natural gas, plotted in X- shaped and comprehensive identification diagrams for the southern area and northern area, respectively, were used to identify the types of natural gas. The large-scale distribution of natural gas is highly consistent with the Ro values of major source rocks, but is poorly correlated with the type of organic matter. This indicates that the main controlling factor of natural gas distribution is organic matter maturity, and the kerogen types act as the basis for the formation of different types of natural gas. Paleouplifts and squeezed anticlines near hydrocarbon generation depression centers, which are major natural gas-rich regions, control the migration directions of natural gas, while hydrocarbon migration pathways and fault systems connecting gas sources are the most important factors for natural gas reservoir formation in the inner basin. Therefore, favorable zones for natural gas distribution can be predicted on the basis of the distribution of thermal evolution and the gas generation intensity of major source rocks as well as the structural map. The Shizigou-Youshashan- Yingdong-Dawusi, Youquanzi -Kaitemilike - Youdunzi, and Xiaoliangshan - Nanyishan - Dafengshan structural belts are favorable zones for natural gas accumulation. This study has important theoretical and practical significance for future natural gas exploration.展开更多
The Heihe River Basin is located in the arid and semi-arid regions of Northwest China.Here,the terrestrial ecosystem is vulnerable,making it necessary to identify the factors that could affect the ecosystem.In this st...The Heihe River Basin is located in the arid and semi-arid regions of Northwest China.Here,the terrestrial ecosystem is vulnerable,making it necessary to identify the factors that could affect the ecosystem.In this study,MODIS-NDVI data with a 250-m resolution were used as a proxy for the terrestrial ecosystem.By combining these with environmental factors,we were able to explore the spatial features of NDVI and identify the factors influencing the NDVI distribution in the Heihe River Basin during the period of 2000–2016.A geographical detector(Geodetector) was employed to examine the spatial heterogeneity of the NDVI and to explore the factors that could potentially influence the NDVI distribution.The results indicate that:(1) the NDVI in the Heihe River Basin appeared high in the southeast while being low in the north,showing spatial heterogeneity with a q-statistic of 0.38.The spatial trend of the vegetation in the three sub-basins generally increased in the growing seasons from 2000 to 2016;(2) The results obtained by the Geodetector(as denoted by the q-statistic as well as the degree of spatial association between the NDVI and environmental factors) showed spatial heterogeneity in the associations between the NDVI and the environmental factors for the overall basin as well as the sub-basins.Precipitation was the dominant factor for the overall basin.In the upper basin,elevation was found to be the dominant factor.The dominant factor in the middle basin was precipitation,closely followed by the soil type.In the lower basin,the dominant factor was soil type with a lower q-statistic of 0.13,and the dominant interaction between the elevation and soil type was nonlinearly enhanced(q-statistic = 0.22).展开更多
According to the differences of structural deformation characteristics, the southern margin of the Junggar basin can be divided into two segments from east to west. Arcnate thrust-and-fold belts that protrude to the n...According to the differences of structural deformation characteristics, the southern margin of the Junggar basin can be divided into two segments from east to west. Arcnate thrust-and-fold belts that protrude to the north are developed in the eastern segment. There are three rows of en echelon thrust-and-fold belts in the western segment. Thrust and fold structures of basement-involved styles are developed in the first row, and decollement fold structures are formed from the second row to the third row. In order to study the factors controlling the deformation of structures, sand-box experiments have been devised to simulate the evolution of plane and profile deformation. The planar simulation results indicate that the orthogonal compression coming from Bogeda Mountain and the oblique compression with an angle of 75° between the stress and the boundary originating from North Tianshan were responsible for the deformation differences between the eastern part and the western part. The Miquan-Uriimqi fault in the basement is the pre-existing condition for generating fragments from east to west. The profile simulation results show that the main factors controlling the deformation in the eastern part are related to the decollement of Jurassic coal beds alone, while those controlling the deformation in the western segment are related to both the Jurassic coal beds and the Eogene clay beds. The total amount of shortening from the Yaomoshan anticline to the Gumudi anticline in the eastern part is -19.57 km as estimated from the simulation results, and the shortening rate is about 36.46%; that from the Qingshuihe anticline to the Anjihai anticline in the western part is -22.01 km as estimated by the simulation results, with a shortening rate of about 32.48%. These estimated values obtained from the model results are very close to the values calculated by means of the balanced cross section.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51721006)
文摘The integration of rivers and basins highly implies the possible existence of certain relationships between hierarchical characteristics of river networks and primary basin factors.Here we investigated river networks in two large basins,the Yangtze River and the Yellow River,characterized with basic factors such as annual precipitation,slope,soil erodibility and vegetation.Hierarchical analysis demonstrated a fair self-similarity of river networks at the stream-order 1-5 in both rivers,described by the structural parameters including bifurcation ratio,side-branching ratio,drainage density,and length of headwater-river.Besides precipitation,basin slope was essential in shaping river networks in both basins,showing a significant positive correlation(R^2=0.39-0.85)to bifurcation ratio,side-branching ratio,and drainage density.Given the same basin slope(5°-15°),the higher soil erodibility and sparse vegetation would promote greater side-branching ratio and drainage density in the Yellow River,which were estimated 11.97%and 63.70%larger,respectively than those in the Yangtze River.This study highlights the importance to formulate basin-specific strategies for water and soil conservation in terms of different structures of river networks.
基金This work was supported by the National Natural Science Foundation of Chinathe Yellow River Water Conservancy Commiss ion(Grant No.50239080)the Major State Basic Research Development Program of China(Grant No.G1999043604).
文摘Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River in relation to natural and human factors in the drainage basin, such as the annual precipitation in different water and sediment source areas, proportion of >0.05 mm sediment of the total sediment load to the lower reaches of Yellow River, the regu-lated degree of the “clear” baseflow from the drainage area above Lanzhou, frequency of hy-perconcentrated flows, area of soil and water conservation measures in the drainage basin. As a result, a multiple regression equation has been established between Fs and 7 influencing factors, with multiple correlation coefficient r = 0.90. The reduction in annual precipitation in different water and sediment source areas has different effects on Fs. The reduction in annual precipitation in the area above Hekou Town and the area between Longmen and Sanmenxia results in a reduction in Fs, but the reduction in annual pre-cipitation in the area between Hekou Town and Longmen results in an increase in Fs. The grain size composition of sediment load strongly affects the Fs; the larger the proportion of >0.05 mm sediment in the suspended sediment load entering the lower reaches of the Yellow River is, the lower the Fs will be. Thus, if the Xiaolangdi Reservoir traps coarse sediment and releases fine sediment, Fs will be enhanced. This study also shows that the lower the proportion of high-flow season river flow to the annual total river flow at Lanzhou Station is, the lower the Fs will be. Therefore, the interception of large quantities of clear water by the reservoirs on the upper reaches of Yellow River is one of the major causes for the decrease in Fs in the lower reaches of the Yellow River.
基金supported by the National Natural Science Foundation of China (No.41402144)
文摘In the eastern Ordos basin, due to the diversity of the tectonic setting, coal rank, gas content and permeability, coal reservoirs have differing characteristics. In this paper, based on coal reservoir geometry, gas content, adsorption capacity, pores and fissures developments and permeability data, the coalbed methane(CBM) reservoir characteristics and their controlling factors in the eastern Ordos basin is discussed. The results show that, due to undergoing different paleo-temperatures in the geological history,coal rank has a higher trend from the north part to the south and from the shallow part to the inward basin, which determines CBM distribution and recoverability. In the north, although having large coal thickness and high permeability, Zhungeer-Xingxian coal rank is low, and gas content is small. In the central part, with medium rank, higher gas content and relatively high permeability, and the Wubao-Liulin area is the most favorable area in the eastern Ordos basin. In the southern part, medium and high metamorphism coal occurs, and although having the highest gas content, the permeability in the Hancheng area is low due to the development of sheared coal.
基金National Natural Science Foundation of China,No.41671098, No.42071288National Key Research and Development Program of China,No.2018YFC1508900, No.2018YFC1508801Beijing Environmental Quality Monitoring Project (2018),No.Y88M1800AL。
文摘A clear understanding of the relationships among multiple ecosystem services(ESs) is the foundation for sustainable urban ecosystem management. Quantitatively identifying the factors that influence ES trade-offs and synergies can contribute to deepening ES research, from knowledge building to decision making. This study simulated soil conservation, water yield and carbon sequestration in Beijing, China, from 2015–2018. The spatial trade-offs and synergies of these three ESs within the five major river basins in Beijing were explored using geographically weighted regression. Furthermore, geographical detector was applied to quantitatively identify the driving mechanism of the environmental factors for the ES trade-offs and synergies. The results show the following:(1) the spatial relationships between soil conservation and water yield, as well as between water yield and carbon sequestration, were mainly trade-offs. There was a spatial synergy between soil conservation and carbon sequestration.(2) Regarding the spatial trade-off/synergy between soil conservation and water yield in Beijing, the dominant influencing factor was temperature/elevation, and the dominant interactions of the spatial trade-off and synergy between these two ESs in Beijing and the Chaobai River Basin are all manifested in the superposition of precipitation and potential evapotranspiration, temperature, and elevation.(3) Topographic factors were the dominant factors influencing the spatial relationship between soil conservation and carbon sequestration in Beijing and its five major river basins. As a result of the distribution of water systems and hydrological characteristics of the basins, differences were observed in the effects of different combinations of interaction factors on the spatial relationship between these two ESs in different basins.(4) Temperature had the strongest explanatory power in terms of the spatial trade-offs and synergies between water yield and carbon sequestration. The interactions between precipitation and temperature and between precipitation and elevation were the dominant interactions affecting the spatial relationship between water yield and carbon sequestration in Beijing. Overall, the explanatory power of influencing factors on the trade-offs and synergies and the degree of interaction between factors coexist in different basins with consistency and differences. Therefore, understanding the quantitative characteristics of basin-scale spatial trade-offs and synergies between ESs is important for ecosystem management and the promotion of synergy in different basins.
基金supported by the National Natural Science Foundation of China(Grant No.91125015)the Central Nonprofit Research Institutes Fundamental Research of the Yellow River Institute of Hydraulic Research(Grant No.HYK-JBYW-2013-18)
文摘On the basis of daily meteorological data from 15 meteorological stations in the Heihe River Basin （HRB） during the period from 1959 to 2012, long-term trends of reference evapotranspiration （ET0） and key meteorological factors that affect ET0 were analyzed using the Mann- Kendall test. The evaporation paradox was also investigated at 15 meteorological stations. In order to explore the contribution of key meteo- rological factors to the temporal variation of ET0, a sensitivity coefficient method was employed in this study. The results show that： （1） mean annual air temperature significantly increased at all 15 meteorological stations, while the mean annual ET0 decreased at most of sites; （2） the evaporation paradox did exist in the HRB, while the evaporation paradox was not continuous in space and time; and （3） relative humidity was the most sensitive meteorological factor with regard to the temporal variation of ET0 in the HRB, followed by wind speed, air temperature, and solar radiation. Air temperature and solar radiation contributed most to the temporal variation of ETo in the upper reaches; solar radiation and wind speed were the determining factors for the temporal variation of ET0 in the middle-lower reaches.
基金sponsored by the construction of urban geological environment monitoring network in Guanzhong urban agglomeration,China geological survey,Project No.Water[2012]01-007-002the research of groundwater dynamic monitoring in Shaanxi province,Shaanxi public welfare geological project,Project No.20130203
文摘This paper studies the distribution features, the chemical elements beyond standards and the influencing factors of shallow groundwater quality in the Guanzhong Basin through the data monitored in the last twenty years. The final purpose is to comprehensively evaluate the divisions of groundwater quality in the Guanzhong Basin. Results show that, the groundwater quality is in good shape, and suitable for drinking. Drinking accounts for 16.02% of the total, most of which are distributed in the lubotan of Weibei. Some come from loess plateau of Qian-Liquan County and some are generated by the industrial pollution of Xingping City. Materials exceeding standards include chloride, sulfate, three nitrogen, fluoride, manganese, iron, hexavalent chromium and so on. The main factors influencing the quality of shallow groundwater include groundwater exploitation, natural background value of special components and precipitation, among which the groundwater exploitation poses the greatest impact. The depth of water is positively correlated with the concentration of sulfate, nitrate and total hardness.
基金granted by the Important National Science&Technology Specific Projects(grants No.2011ZX05006-003 and 2016ZX05006-003)the National Natural Science Foundation(grant No.41372132)
文摘Significant differential hydrocarbon enrichment occurs in depressions in a petroliferous basin.There are multiple depressions in the Bohai Bay Basin, and each depression as a relatively independent unit of hydrocarbon generation, migration and accumulation, contains significantly different hydrocarbon generation conditions and enrichment degree. On the basis of previous documents and a large number of statistical data, this work comparatively analyzed the differential hydrocarbon enrichment and its major controlling factors in depressions of the Bohai Bay Basin. The results show that depressions in the Bohai Bay Basin have various hydrocarbon enrichment degrees, and can be categorized into four types, namely enormously oil-rich, oil-rich, oily and oil-poor depressions. In general, the enormously oil-rich and oil-rich depressions are distributed in the eastern part of the basin along the Tan-Lu and Lan-Liao faults, whereas depressions in the western part of the basin are poor in hydrocarbons. Moreover, the vertical distribution of hydrocarbons is also highly heterogeneous, with Pre-Paleogene strata rich in hydrocarbons in the northern and western depressions, Paleogene strata rich in hydrocarbons in the entire basin, and Neogene strata rich in hydrocarbons in the off-shore areas of the Bohai Bay Basin. From early depressions in onshore areas to the late depressions in offshore areas of the Bohai Bay Basin, the source rocks and source-reservoir-cap rock assemblages gradually become younger and shallower, and the hydrocarbon resource abundance gradually increases. Hydrocarbon supplying condition is the key factor constraining the hydrocarbon enrichment for different depressions,while the main source-reservoir-cap rock assemblage, sufficient hydrocarbons and the transportation capacity of faults control the vertical distribution of hydrocarbons. The main factors controlling hydrocarbon enrichment are different for different layers. The hydrocarbon supplying condition of source rocks is the key controlling factor, whereas the source-reservoir configuration, the main sourcereservoir-cap rock assemblages, and the fault transportation are the main factors of hydrocarbon enrichment in the Paleogene, Paleogene and Neogene, respectively.
基金supported by the Scientific Research Project of SINOPEC Scientific Development Department (No. P08062)
文摘ABSTRACT： Tabei （塔北） uplift is an area with the highest hydrocarbon enrichment in Tarim basin, and large oilfields have been found on Akekule （阿克库勒） arch at the middle section of Tabei uplift, with Ordovician carbonate reservoirs. Storage space of the Ordovician carbonate reservoirs in the Akekule arch are mainly caves, pores and fractures resulted from dissolution and/or karstification. The Ordovician carbonate reservoirs are affected and modified by the diagenetie process in penecontemporaneous, epigenetic and burial periods and the multi-stage karstification related with deep hydrothermal activities, among which the most significant effect is from the meteoric water karstification related to the tectonic uplift from the end of Middle Ordovician to the end of Late Ordovician （end of O2-end of 03） and at the end of Middle Devonian （end of D2）. Varied palacogeologic settings and tectonic features at different geologic periods lead to different fluid flowing patterns, karstification mechanisms and transformation features in different regions, which further influence the reservoir distribution. The paleo-uplifts at different periods, such as end of O2-end of 03 and end of D2, control the dominant development zones of karstification; the paleogeomorphology and faults resulted from tectonic uplift control the flowing depth of the karst fluid; and the lithology controls the position and extent of karst development.
文摘The earliest agricultural activities in Sichuan Basin can be traced hack to the middle Neolithic Age. hang the development process afterwards, the on and ha dynasties, the Sui and Tang dynasties, and the Northern Song Dynasty were three peaks of agricultural development. The various natural conditions resulted in a variety of agriculrural Patterns in Sichuan Basin. The drainage system Played a major role and always went before land and agricultural development in different historical periods. The wars and natural disasters in the end of the Ming Dynasty severely damaged the agricultural system. It was until the early and middle Qing Dynasty that many immigrants fm other provinces restored and promoted the agricultural activities in Sichuan Basin.
文摘The multi-factor recombination and processes superimposition model for hydrocarbon accumulation is put forward in view of the hydrocarbon geological characteristics of multiple episodes of structural evolution, multiple sets of source-reservoir-seal assemblage, multiple cycles of hydrocarbon accumulation and multiple episodes of readjustment and reconstruction in the complex superimposed basins in China. It is a system including theories and methods that can help to predict favorable exploration regions. According to this model, the basic discipline for hydrocarbon generation, evolution and distribution in the superimposed basins can be summarized in multi-factor recombination, processes superimposition, multiple stages of oil filling and latest stage preservation. With the Silurian of the Tarim basin as an example, based on the reconstruction of the evolution history of the four factors （paleo-anticline, source rock, regional cap rock and kinematic equilibrium belt） controlling hydrocarbon accumulation, this model was adopted to predict favorable hydrocarbon accumulation areas and favorable exploration regions following structural destruction in three stages of oil filling, to provide guidance for further exploration ofoil and gas in the Silurian of the Tarim basin.
文摘Objective: In this study, the influence and response relationship between the seasonal freezing-thawing process of soil and the spatial factor changes in the management and utilization of water resource processes were explored. Methods: The monitoring equipment in this study was arranged at different altitudes, gradients, and slope directions, such as the typical forest sample area in the Dayekou Basin of the Qilian Mountains. The spatial variation characteristics of the seasonal freezing-thawing process of the soil were analyzed, and a regression model was established. Results: 1) The results of this study determined that the rate of the soil’s freezing increased with the altitude in a trend of volatility. However, the rate of the thawing of the frozen soil was found to have an opposite trend. The variation degree of the freezing-thawing process increased with the altitude in a trend of volatility. The end time of the approximate soil freezing with altitude increased in a volatility trend ahead of schedule. However, the opposite was observed in the thawing rate of the frozen soil;2) The rate of the soil’s freezing under the mosses of the spruce forest at an altitude of 3028 m was found to be the lowest. However, in the sub-alpine scrub forest at an altitude of 3300 m, a maximum in the spatial ordering was observed, with an average of 1.9 cm·d-1. The thawing rate of the frozen soil in scrub-spruce forest at an altitude of 3300 m was found to be minimal. However, in the sunny slope grassland at an altitude of 2946 m, a maximum in the spatial ordering was observed, with an average of 1.5 cm·d-1. In the spatial ordering of the variation degree of the process of freezing-thawing with an average of 1.2, the scrub-grassland at an altitude of 2518 m was found to be the lowest, and the scrub-spruce forest at an altitude of 3195 m was also low;3) The soil freezing began on approximately October 20th, and the rate of soil freezing gradually became reduced. The arrival time of the frozen soil of up to 150 cm in depth in sub-alpine scrub forest was first observed at an altitude of 3028 m. However, the scrub-spruce forest at an altitude of 3100 m did not become frozen until approximately January 12th on average. Then, the thawing rate of the frozen soil increased gradually. The end time of the thawing was earliest observed in the sunny slope grassland at an altitude of 2946 m. However, the scrub-spruce forest at an altitude of 3100 m was found to be the last to thaw, and averaged approximately July 27th. The average durations of the freezing and thawing of the soil were 77 and 121 days, respectively, and the average duration of the entire process of freezing-thawing was 199 days;4) This study’s established regression models of the duration time of frozen soil’s thaw, and the rate of frozen soil’s thaw, all passed the R test of goodness of fit, F test of variance, and t test. Conclusions: The characteristics of the seasonal freezing-thawing process of the soil with the spatial changes were seasonal. However, the characteristics under the different spatial factor influences were not the same.
文摘[Objective] The change rules of Lycium barbarum and meteorological factors in Qaidam Basin were studied. [Method] Botanical characteristics,growth characteristics and physiological factor changes of Ningqi 1 were analyzed,and the change laws of Ningqi 1 and environmental factors(including sunlight,temperature,water and soil) were investigated by using meteorological observation data in 1973-2008. [Results] The results showed that Ningqi 1 belonged to light preferring plant,and the higher photosynthetic rate showed double peak type with the peaks appearing at 12:00 and 16:00,having midday depression of photosynthesis. The diurnal variation of transpiration rate in leaves showed a double peak,and the temperature around leaves was 0.2-0.5 ℃ higher than that in the field. The average relative humidity and temperature were the key factors to affect forming L. barbarum fruits. The suitable temperature for developing big seeds was 18 ℃. [Conclusions] Ningqi 1 could be taken as the first choice variety to plant and popularize in Qaidam Basin.
基金supported financially by the National Science and Technology Major Project"Chinese large gasfields’formation conditions,accumulation and objective evaluation"(2011ZX05007)the Major Special Project of Chinese Petroleum Development Technologies"A study on comprehensive supporting technologies for building oil-gas field of ten million tons in Qaidam basin"(2011E-03)
文摘The Paleogene and Neogene oil and gas in the western Qaidam basin have a regular distribution in three concentric zones from the edge to the center of the basin. Natural gas mainly occurs in the inner zone, and the gas-oil ratio of the northern area of the basin is significantly higher than that of the southern area. Large amounts of carbon isotope data of natural gas, plotted in X- shaped and comprehensive identification diagrams for the southern area and northern area, respectively, were used to identify the types of natural gas. The large-scale distribution of natural gas is highly consistent with the Ro values of major source rocks, but is poorly correlated with the type of organic matter. This indicates that the main controlling factor of natural gas distribution is organic matter maturity, and the kerogen types act as the basis for the formation of different types of natural gas. Paleouplifts and squeezed anticlines near hydrocarbon generation depression centers, which are major natural gas-rich regions, control the migration directions of natural gas, while hydrocarbon migration pathways and fault systems connecting gas sources are the most important factors for natural gas reservoir formation in the inner basin. Therefore, favorable zones for natural gas distribution can be predicted on the basis of the distribution of thermal evolution and the gas generation intensity of major source rocks as well as the structural map. The Shizigou-Youshashan- Yingdong-Dawusi, Youquanzi -Kaitemilike - Youdunzi, and Xiaoliangshan - Nanyishan - Dafengshan structural belts are favorable zones for natural gas accumulation. This study has important theoretical and practical significance for future natural gas exploration.
基金National Key R&D Program of China,No.2017YFA0604704
文摘The Heihe River Basin is located in the arid and semi-arid regions of Northwest China.Here,the terrestrial ecosystem is vulnerable,making it necessary to identify the factors that could affect the ecosystem.In this study,MODIS-NDVI data with a 250-m resolution were used as a proxy for the terrestrial ecosystem.By combining these with environmental factors,we were able to explore the spatial features of NDVI and identify the factors influencing the NDVI distribution in the Heihe River Basin during the period of 2000–2016.A geographical detector(Geodetector) was employed to examine the spatial heterogeneity of the NDVI and to explore the factors that could potentially influence the NDVI distribution.The results indicate that:(1) the NDVI in the Heihe River Basin appeared high in the southeast while being low in the north,showing spatial heterogeneity with a q-statistic of 0.38.The spatial trend of the vegetation in the three sub-basins generally increased in the growing seasons from 2000 to 2016;(2) The results obtained by the Geodetector(as denoted by the q-statistic as well as the degree of spatial association between the NDVI and environmental factors) showed spatial heterogeneity in the associations between the NDVI and the environmental factors for the overall basin as well as the sub-basins.Precipitation was the dominant factor for the overall basin.In the upper basin,elevation was found to be the dominant factor.The dominant factor in the middle basin was precipitation,closely followed by the soil type.In the lower basin,the dominant factor was soil type with a lower q-statistic of 0.13,and the dominant interaction between the elevation and soil type was nonlinearly enhanced(q-statistic = 0.22).
基金financially supported by the National Natural Science Foundation of China(No.40972091)
文摘According to the differences of structural deformation characteristics, the southern margin of the Junggar basin can be divided into two segments from east to west. Arcnate thrust-and-fold belts that protrude to the north are developed in the eastern segment. There are three rows of en echelon thrust-and-fold belts in the western segment. Thrust and fold structures of basement-involved styles are developed in the first row, and decollement fold structures are formed from the second row to the third row. In order to study the factors controlling the deformation of structures, sand-box experiments have been devised to simulate the evolution of plane and profile deformation. The planar simulation results indicate that the orthogonal compression coming from Bogeda Mountain and the oblique compression with an angle of 75° between the stress and the boundary originating from North Tianshan were responsible for the deformation differences between the eastern part and the western part. The Miquan-Uriimqi fault in the basement is the pre-existing condition for generating fragments from east to west. The profile simulation results show that the main factors controlling the deformation in the eastern part are related to the decollement of Jurassic coal beds alone, while those controlling the deformation in the western segment are related to both the Jurassic coal beds and the Eogene clay beds. The total amount of shortening from the Yaomoshan anticline to the Gumudi anticline in the eastern part is -19.57 km as estimated from the simulation results, and the shortening rate is about 36.46%; that from the Qingshuihe anticline to the Anjihai anticline in the western part is -22.01 km as estimated by the simulation results, with a shortening rate of about 32.48%. These estimated values obtained from the model results are very close to the values calculated by means of the balanced cross section.
