[Objective] The paper was to discuss why the top of tall barchan dunes and barchan chains widespread in single prevailing wind area had not been leveled by wind erosion. [Method] Based on the preliminary survey of dis...[Objective] The paper was to discuss why the top of tall barchan dunes and barchan chains widespread in single prevailing wind area had not been leveled by wind erosion. [Method] Based on the preliminary survey of distribution status,the morphological characteristics and environmental conditions of barchan dunes and barchan chains in Hexi desert area of Gansu were investigated in details. The significance of difference between samples and significance of correlation between indicators were examined via variance test. [Result] Barchan dunes and barchan chains in Hexi desert area of Gansu distributed at the leeward direction of desert fringe,generally in patch distribution. The distribution area was gravelly beach or cohesive gravel beach,with broader dune slack; winds in distribution area of barchan dunes and barchan chains blew obviously from one direction,while winds at other directions were light or occasionally strong but with low frequency;the barchan dune in the desert fringe of Hexi desert area of Gansu was relatively tall,while barchan chain was even more taller and larger. Coincidence or separation of the dune peak and the sand ridge might be related to distribution frequency of dominant prevailing wind or wind at opposite direction and the observation seasons.[Conclusion]Studying top stability of barchan dune has an important academic value in revealing blowing sand movement rule at desert fringe,invasion of sand flow,and expansion of desert.展开更多
By processing and analyzing geodetic data of vertical deformation, fault deformation and horizontal deformation by GPS in Gansu Ningxia Qinghai area and by comparing them with geological structures and many medium to ...By processing and analyzing geodetic data of vertical deformation, fault deformation and horizontal deformation by GPS in Gansu Ningxia Qinghai area and by comparing them with geological structures and many medium to strong earthquake activities in this area, some features of recent tectonic deformation anomaly and the development of medium to strong earthquakes are studied. The results show that: ①Near the main faults tectonic deformations are relatively large. The amount of vertical movement and the deformation status evolve with time. The horizontal movement and deformation show obvious compressional strike slip character. ②The dominant stress of tectonic deformation and seismic development in this area comes from the persistent northeastward compression of Qinghai Tibet block;The time spatial distribution evolution of tectonic deformation and seismic activities are closely related to dynamic evolution of block motion and regional tectonic stress field. ③The abnormal uplift and high gradient deformation belts and remarkable fault deformation anormaly on the borders of regional tectonic blocks are indicators of developing moderate to strong earthquakes but earthquakes may not necessarily take place in the position of maxium deformation, it usually occurred in the region where fault deformation anormaly shows “trend accumulation acceleration turn ” variation character or nearby. On the basis of above study, a preliminary prediction for strong earthquake risk in this area is given.展开更多
Taking Gansu province as a model case,this study provides an integrated analysis on the eco-economic system of arid and semi-arid region based on emergy synthesis theory. Through calculating the values of renewable em...Taking Gansu province as a model case,this study provides an integrated analysis on the eco-economic system of arid and semi-arid region based on emergy synthesis theory. Through calculating the values of renewable emergy flow,non-renewable resources,imported emergy,exported emergy,waste emergy,and total emergy during the period of 1978-2007,the performance of Gansu eco-economic system was analyzed. The results indicated that the renewable emergy flow within the province basically remained steady state which was estimated at 2.99×1022 solar emjoules (sej) from 1978 to 2007. The imported emergy and exported emergy were estimated at 3.75×1017 sej and 2.99×1020 sej in 1978 and increased to 1.07×1022 sej and 1.44×1022 sej respectively in 2007. The nonrenewable emergy flow was estimated at 1.62×1022 sej and increased to 1.85×1023 sej,with annual growth rate of 8.7%,while the estimated total emergy was 4.58×1022 sej in 1978 and increased to 2.11×1023 sej in 2007,with annual growth rate of 5.41%. Our results indicate a deteriorate situation between economic development and environmental protection in the region. The rapid economic growth in the past thirty years was based on a great consumption of nonrenewable resource and caused continuous decrease in the capacity of sustainable development. The environmental loading ratio was 0.53 in 1978,increased to 6.06 in 2007,indicating a rapid degradation of the regional environment quality. We calculated that the actual population was 1.53 times the renewable resource population in 1978,increased to 7.06 times in 2007. During the period of 1978-2007,the emergy rose from 2.45×1015 sej/(capita·a) to 8.07×1015 sej/(capita·a). Our analysis revealed that the emergy density presented a trend of gradual increase,and then the emergy currency ratio in Gansu decreased from 7.08×1013 sej/Chinese Yuan to 7.82×1012 sej/Chinese Yuan.展开更多
The research and development of high-level radioactive waste(HLW)repository is a long-term systematic engineering project.Normally,it involves such stages as foundation study,site selection and assessment,underground ...The research and development of high-level radioactive waste(HLW)repository is a long-term systematic engineering project.Normally,it involves such stages as foundation study,site selection and assessment,underground research laboratory testing, and the design,construction,operation,and close of the repository.The key issue in repository design展开更多
[Objective] The paper was to study the particle size characteristics of barchan dune and its formation mechanism in Hexi desert area of Gansu. [Method] Through particle size measurement and wind speed flow field obser...[Objective] The paper was to study the particle size characteristics of barchan dune and its formation mechanism in Hexi desert area of Gansu. [Method] Through particle size measurement and wind speed flow field observation of dune,the particle size differences of various sampling plots and various parts of dune were analyzed using analysis of variance,and the relationship between particle size and wind speed was analyzed using correlation coefficient method. [Result]( 1) Barchan dune and barchan chains in Hexi desert area of Gansu were mainly consisted of fine sands and medium sands at the depth of 0- 5 cm: the sand particle in Gulang desert area was fine,which had significant difference with that in Jinchang,Linze,Jinta and Minqin desert areas.( 2) Medium sands gradually increased from the bottom of windward slope to the dune peak in both barchan dune and barchan chain. On the windward slope of barchan dune,fine sands gradually increased from the middle to both sides,while coarse sands and medium sands gradually decreased. On the windward slope of barchan chain,fine sands first decreased then increased from the middle to NE side,but first increased then decreased from the middle to SW side.( 3) In terms of particle size,there were great variations between fine sands and coarse sands; for dune parts,there were great variations between dune peak and leeward slope toe; for dune types,the variation of fine sands in various parts of barchan chain was greater than that of barchan dune,while differentiation degree of medium sands and fine sands was greater than that of barchan dune. The particle size of fine sands was positively correlated with wind speed,and that of medium sands was negatively correlated with wind speed.[Conclusion]The formation environment of particle size of barchan dune mainly included sand source and dynamic source,and wind speed was the dynamic source for particle size distribution of barchan dune.展开更多
Barchan dunes are a common type of dune. There are a lot of barchan dunes at accumulated sand-belts of the oasis edge of Hexi desert area of Gansu. What is characteristic of the particle size of barchan dunes? How is ...Barchan dunes are a common type of dune. There are a lot of barchan dunes at accumulated sand-belts of the oasis edge of Hexi desert area of Gansu. What is characteristic of the particle size of barchan dunes? How is this particle size characteristic formed? Characteristics of particle size were analyzed in this paper by comprehensive investigation and sampling in Hexi Corridor desert area, and repeated sampling and determination in Minqin desert area. The results showed that:(1) The particle size of 0.25–0.05 mm and particle size of 0.5–0.25 mm were the main ingredients at the surface 0–5 cm depth of barchan dunes and barchan dune chains in desert area in Hexi Corridor of Gansu. Sand in Gulang desert area was relatively finer and the particle size was quite different from that of Jinchang, Linze, Jinta and Minqin desert area;(2) The particle size was changed from coarse to fine from the bottom to the top of the dunes in the main wind direction(NW) process. i.e. there was the most silt at the top of the dunes, followed by the middle of the leeward slope. The bottom of the windward slope had the most coarse sand, followed by the middle of the windward slope. The barchan dunes were changed from coarse to fine, then from fine to coarse from the bottom to the top of the dunes in the reverse wind direction(SE) process, i.e. there was the most silt in the middle of the windward slope, followed by the top of sand dunes. The bottom of the windward slope had the most coarse sand, followed by the middle of the windward slope. The standard deviation and coefficient of variation of sand dune particle size in the main wind direction process was larger, and the standard deviation and coefficient of variation of sand dune particle size in the reverse wind direction process was smaller;(3) The two processes of the main wind direction(NW) and the reverse wind direction(SE) led to alternating changes in particle size in various parts of the dunes. Two different conclusions on particle size distribution of barchan dunes in windward slope were due to the observation season differences.展开更多
基金Supported by Special Project for Preceding Study of 973 Program"Stability Research of Tall Barchan Dune at Oasis Fringe(2014CB460611)National Natural Science Foundation of China"Climatic and Environmental Factors for Formation of Sand Sediment Zone and Its Ecological Effects at Minqin Oasis Fringe of Gansu Province(41261102)
文摘[Objective] The paper was to discuss why the top of tall barchan dunes and barchan chains widespread in single prevailing wind area had not been leveled by wind erosion. [Method] Based on the preliminary survey of distribution status,the morphological characteristics and environmental conditions of barchan dunes and barchan chains in Hexi desert area of Gansu were investigated in details. The significance of difference between samples and significance of correlation between indicators were examined via variance test. [Result] Barchan dunes and barchan chains in Hexi desert area of Gansu distributed at the leeward direction of desert fringe,generally in patch distribution. The distribution area was gravelly beach or cohesive gravel beach,with broader dune slack; winds in distribution area of barchan dunes and barchan chains blew obviously from one direction,while winds at other directions were light or occasionally strong but with low frequency;the barchan dune in the desert fringe of Hexi desert area of Gansu was relatively tall,while barchan chain was even more taller and larger. Coincidence or separation of the dune peak and the sand ridge might be related to distribution frequency of dominant prevailing wind or wind at opposite direction and the observation seasons.[Conclusion]Studying top stability of barchan dune has an important academic value in revealing blowing sand movement rule at desert fringe,invasion of sand flow,and expansion of desert.
文摘By processing and analyzing geodetic data of vertical deformation, fault deformation and horizontal deformation by GPS in Gansu Ningxia Qinghai area and by comparing them with geological structures and many medium to strong earthquake activities in this area, some features of recent tectonic deformation anomaly and the development of medium to strong earthquakes are studied. The results show that: ①Near the main faults tectonic deformations are relatively large. The amount of vertical movement and the deformation status evolve with time. The horizontal movement and deformation show obvious compressional strike slip character. ②The dominant stress of tectonic deformation and seismic development in this area comes from the persistent northeastward compression of Qinghai Tibet block;The time spatial distribution evolution of tectonic deformation and seismic activities are closely related to dynamic evolution of block motion and regional tectonic stress field. ③The abnormal uplift and high gradient deformation belts and remarkable fault deformation anormaly on the borders of regional tectonic blocks are indicators of developing moderate to strong earthquakes but earthquakes may not necessarily take place in the position of maxium deformation, it usually occurred in the region where fault deformation anormaly shows “trend accumulation acceleration turn ” variation character or nearby. On the basis of above study, a preliminary prediction for strong earthquake risk in this area is given.
基金funded by the Natural Science Foundation of China (40871061)Initial Fund for Doctors of Institute of Applied Ecology at Chinese Academy of Sciences (Y0SBS161S3)+2 种基金100 Talents Program of the Chinese Academy of Sciences (08YBR111SS)Shenyang Bureau of Science and Technology (1091147-9-00)Natural Science Foundation of Liaoning province (20092078)
文摘Taking Gansu province as a model case,this study provides an integrated analysis on the eco-economic system of arid and semi-arid region based on emergy synthesis theory. Through calculating the values of renewable emergy flow,non-renewable resources,imported emergy,exported emergy,waste emergy,and total emergy during the period of 1978-2007,the performance of Gansu eco-economic system was analyzed. The results indicated that the renewable emergy flow within the province basically remained steady state which was estimated at 2.99×1022 solar emjoules (sej) from 1978 to 2007. The imported emergy and exported emergy were estimated at 3.75×1017 sej and 2.99×1020 sej in 1978 and increased to 1.07×1022 sej and 1.44×1022 sej respectively in 2007. The nonrenewable emergy flow was estimated at 1.62×1022 sej and increased to 1.85×1023 sej,with annual growth rate of 8.7%,while the estimated total emergy was 4.58×1022 sej in 1978 and increased to 2.11×1023 sej in 2007,with annual growth rate of 5.41%. Our results indicate a deteriorate situation between economic development and environmental protection in the region. The rapid economic growth in the past thirty years was based on a great consumption of nonrenewable resource and caused continuous decrease in the capacity of sustainable development. The environmental loading ratio was 0.53 in 1978,increased to 6.06 in 2007,indicating a rapid degradation of the regional environment quality. We calculated that the actual population was 1.53 times the renewable resource population in 1978,increased to 7.06 times in 2007. During the period of 1978-2007,the emergy rose from 2.45×1015 sej/(capita·a) to 8.07×1015 sej/(capita·a). Our analysis revealed that the emergy density presented a trend of gradual increase,and then the emergy currency ratio in Gansu decreased from 7.08×1013 sej/Chinese Yuan to 7.82×1012 sej/Chinese Yuan.
文摘The research and development of high-level radioactive waste(HLW)repository is a long-term systematic engineering project.Normally,it involves such stages as foundation study,site selection and assessment,underground research laboratory testing, and the design,construction,operation,and close of the repository.The key issue in repository design
基金Supported by Special Project for Preceding Study of 973 Program "Stability Research of Tall Barchan Dune at Oasis Fringe(2014CB460611)National Natural Science Foundation of China "Climate Factors and Their Ecological Effects on Formation of Accumulation Sand-belt at Oasis Edge of Minqin(41261102)
文摘[Objective] The paper was to study the particle size characteristics of barchan dune and its formation mechanism in Hexi desert area of Gansu. [Method] Through particle size measurement and wind speed flow field observation of dune,the particle size differences of various sampling plots and various parts of dune were analyzed using analysis of variance,and the relationship between particle size and wind speed was analyzed using correlation coefficient method. [Result]( 1) Barchan dune and barchan chains in Hexi desert area of Gansu were mainly consisted of fine sands and medium sands at the depth of 0- 5 cm: the sand particle in Gulang desert area was fine,which had significant difference with that in Jinchang,Linze,Jinta and Minqin desert areas.( 2) Medium sands gradually increased from the bottom of windward slope to the dune peak in both barchan dune and barchan chain. On the windward slope of barchan dune,fine sands gradually increased from the middle to both sides,while coarse sands and medium sands gradually decreased. On the windward slope of barchan chain,fine sands first decreased then increased from the middle to NE side,but first increased then decreased from the middle to SW side.( 3) In terms of particle size,there were great variations between fine sands and coarse sands; for dune parts,there were great variations between dune peak and leeward slope toe; for dune types,the variation of fine sands in various parts of barchan chain was greater than that of barchan dune,while differentiation degree of medium sands and fine sands was greater than that of barchan dune. The particle size of fine sands was positively correlated with wind speed,and that of medium sands was negatively correlated with wind speed.[Conclusion]The formation environment of particle size of barchan dune mainly included sand source and dynamic source,and wind speed was the dynamic source for particle size distribution of barchan dune.
基金Sponsored by National Natural Science Foundation of China(41661064)
文摘Barchan dunes are a common type of dune. There are a lot of barchan dunes at accumulated sand-belts of the oasis edge of Hexi desert area of Gansu. What is characteristic of the particle size of barchan dunes? How is this particle size characteristic formed? Characteristics of particle size were analyzed in this paper by comprehensive investigation and sampling in Hexi Corridor desert area, and repeated sampling and determination in Minqin desert area. The results showed that:(1) The particle size of 0.25–0.05 mm and particle size of 0.5–0.25 mm were the main ingredients at the surface 0–5 cm depth of barchan dunes and barchan dune chains in desert area in Hexi Corridor of Gansu. Sand in Gulang desert area was relatively finer and the particle size was quite different from that of Jinchang, Linze, Jinta and Minqin desert area;(2) The particle size was changed from coarse to fine from the bottom to the top of the dunes in the main wind direction(NW) process. i.e. there was the most silt at the top of the dunes, followed by the middle of the leeward slope. The bottom of the windward slope had the most coarse sand, followed by the middle of the windward slope. The barchan dunes were changed from coarse to fine, then from fine to coarse from the bottom to the top of the dunes in the reverse wind direction(SE) process, i.e. there was the most silt in the middle of the windward slope, followed by the top of sand dunes. The bottom of the windward slope had the most coarse sand, followed by the middle of the windward slope. The standard deviation and coefficient of variation of sand dune particle size in the main wind direction process was larger, and the standard deviation and coefficient of variation of sand dune particle size in the reverse wind direction process was smaller;(3) The two processes of the main wind direction(NW) and the reverse wind direction(SE) led to alternating changes in particle size in various parts of the dunes. Two different conclusions on particle size distribution of barchan dunes in windward slope were due to the observation season differences.
