Oasis evolution, one of the most obvious surface processes in arid regions, affects various aspects of the regional environment, such as hydrological processes, ecological conditions, and microclimates. In this paper,...Oasis evolution, one of the most obvious surface processes in arid regions, affects various aspects of the regional environment, such as hydrological processes, ecological conditions, and microclimates. In this paper, the historical spatio-temporal evolution of the cultivated oases in the Heihe River Basin, the second largest inland watershed in the northwest of China, was assessed using multidisciplinary methods and data from multiple sources, including historical literature, ancient sites, maps and remotely sensed images. The findings show that cultivated oases were first developed on a large scale during the Han Dynasty （121 BC-220） and then gradually decreased in extent from the Six Dynasties period （220-581） to the Sui- Tang period （581-907）, reaching a minimum in the Song- Yuan period （960-1368）. An abrupt revival occurred during the Ming Dynasty （1368-1644） and continued through the Qing Dynasty （1644-1911）, and during the period of the Republic of China （1912-1949）, oasis development reached its greatest peak of the entire historical period. The oasis areas during seven major historical periods, i.e., Hart, Six Dynasties, Sui-Tang, Song-Yuan, Ming, Qing, and Republic of China, are estimated to have been 1703 kma, 1115 km2, 629 km2, 614 km2, 964 km2, 1205 km2, and 1917 km2, respectively. The spatial distribution generally exhibited a continuous sprawl process, with the center of the oases moving gradually from the downstream region to the middle and even upstream regions. The oases along the main river remained stable during most periods, whereas those close to the terminal reaches were subject to frequent variations and even abandonment. Socio-economic factors were the main forces driving the evolution of cultivated oases in the area; among them, political and societal stability, national defense, agricultural policy, population, and technological progress were the most important.展开更多
Investigating the attributes of the dual oasis effect and oasis–desert interactions is crucial for understanding the climatic and ecological effects of oases.In this study,oasis effect intensity(OEI)was used as an in...Investigating the attributes of the dual oasis effect and oasis–desert interactions is crucial for understanding the climatic and ecological effects of oases.In this study,oasis effect intensity(OEI)was used as an indicator to investigate the factors that contribute to the dual oasis effect.The oasis effect has two attributes:the surface oasis heating effect(OHE)occurred in winter,while the oasis cooling effect(OCE)occurred in the other three seasons,especially in summer.During the day,the OEI of the whole oasis was−12.8℃,−5.2℃,and−4.5℃ in summer,spring,and autumn,respectively,which indicated a strong OCE;and OEI was 0.5℃ in winter,which indicated a weaker OHE.In arid regions,the OCE dominated most of the time,but the OHE occurred in winter and cannot be ignored.In addition,through statistical analysis and energy balance analysis,high evapotranspiration of the oasis was the main factor leading to the occurrence of OCE in the summer,while low albedo to the occurrence of OHE in winter.展开更多
Introduction:Arid area is an important base for human settlement,however,long and drastic human activities have altered the drainage patterns in the arid watersheds significantly,causing serious ecological consequence...Introduction:Arid area is an important base for human settlement,however,long and drastic human activities have altered the drainage patterns in the arid watersheds significantly,causing serious ecological consequences.This study,through a case study of the Minqin Basin,a microcosm of the artificial oases in the arid northwest China,used the multitypes of data to recover the spatial distribution of human settlement and drainage patterns during historical period and analyze the relationship between them over the past 2000 years.Outcomes:Before the Han Dynasty(121 BC),the utilization of water resources in the Minqin Basin was in the primitive stage and the drainage pattern maintained the natural state.From the Han(121 BC-220)to the Wei-Jin Dynasties(220-316),the utilization of water resources intensified unprecedentedly,but the natural shape of the river systems was still maintained.In the following 1,000 years or so,the drainage pattern was in the state of“following its own course”due to the small human population.In the Ming Dynasty(1368-1644),with the alteration of the main rivers,the water resource utilization increased obviously,but the human reclamations were mainly confined to the southern part of the basin.In the Qing Dynasty(1644-1911),the reclamation of the Liulin Lake area significantly changed the drainage patterns,resulted in the drastically northward expansion of human settlement.Since the foundation of the People’s Republic of China(PRC)in 1949,the artificial water system completely replaced the natural water system and intensified the ecological problems in the basin.Discussion:The changes over the past 2000 years show the drastic impacts of human activities on the alterations of the drainage patterns and related ecological problems in the arid Northwest China.Conclusion:Rehabilitation of such ecological impairments requires both ecological restoration projects and changes in human paradigm and behavior over multiple temporal and spatial scales.展开更多
基金partially supported by the National Key Research and Development Program of China(2016YFA0600104)supported by donations made by Delos Living LLC,and the Cyrus Tang Foundation+2 种基金supported by the National Natural Science Foundation of China(41471419)Beijing Institute of Urban Planningsupported by the Fundamental Research Funds for the Central Universities(CCNU19TD002).
文摘Oasis evolution, one of the most obvious surface processes in arid regions, affects various aspects of the regional environment, such as hydrological processes, ecological conditions, and microclimates. In this paper, the historical spatio-temporal evolution of the cultivated oases in the Heihe River Basin, the second largest inland watershed in the northwest of China, was assessed using multidisciplinary methods and data from multiple sources, including historical literature, ancient sites, maps and remotely sensed images. The findings show that cultivated oases were first developed on a large scale during the Han Dynasty （121 BC-220） and then gradually decreased in extent from the Six Dynasties period （220-581） to the Sui- Tang period （581-907）, reaching a minimum in the Song- Yuan period （960-1368）. An abrupt revival occurred during the Ming Dynasty （1368-1644） and continued through the Qing Dynasty （1644-1911）, and during the period of the Republic of China （1912-1949）, oasis development reached its greatest peak of the entire historical period. The oasis areas during seven major historical periods, i.e., Hart, Six Dynasties, Sui-Tang, Song-Yuan, Ming, Qing, and Republic of China, are estimated to have been 1703 kma, 1115 km2, 629 km2, 614 km2, 964 km2, 1205 km2, and 1917 km2, respectively. The spatial distribution generally exhibited a continuous sprawl process, with the center of the oases moving gradually from the downstream region to the middle and even upstream regions. The oases along the main river remained stable during most periods, whereas those close to the terminal reaches were subject to frequent variations and even abandonment. Socio-economic factors were the main forces driving the evolution of cultivated oases in the area; among them, political and societal stability, national defense, agricultural policy, population, and technological progress were the most important.
基金This work was supported by the National Key R&D Program of China[2018YFA0606404]the National Natural Science Foundation of China[41601064]+1 种基金Strategic Priority Research Program of Chinese Academy of Sciences[XDA2009000001]Technology Basic Resource Investigation Program of China[2017FY101003].
文摘Investigating the attributes of the dual oasis effect and oasis–desert interactions is crucial for understanding the climatic and ecological effects of oases.In this study,oasis effect intensity(OEI)was used as an indicator to investigate the factors that contribute to the dual oasis effect.The oasis effect has two attributes:the surface oasis heating effect(OHE)occurred in winter,while the oasis cooling effect(OCE)occurred in the other three seasons,especially in summer.During the day,the OEI of the whole oasis was−12.8℃,−5.2℃,and−4.5℃ in summer,spring,and autumn,respectively,which indicated a strong OCE;and OEI was 0.5℃ in winter,which indicated a weaker OHE.In arid regions,the OCE dominated most of the time,but the OHE occurred in winter and cannot be ignored.In addition,through statistical analysis and energy balance analysis,high evapotranspiration of the oasis was the main factor leading to the occurrence of OCE in the summer,while low albedo to the occurrence of OHE in winter.
基金This study was partially supported by Natural Science Foundation of China(NSFC Grants:41471163,41530752,91025010,and 40401060).
文摘Introduction:Arid area is an important base for human settlement,however,long and drastic human activities have altered the drainage patterns in the arid watersheds significantly,causing serious ecological consequences.This study,through a case study of the Minqin Basin,a microcosm of the artificial oases in the arid northwest China,used the multitypes of data to recover the spatial distribution of human settlement and drainage patterns during historical period and analyze the relationship between them over the past 2000 years.Outcomes:Before the Han Dynasty(121 BC),the utilization of water resources in the Minqin Basin was in the primitive stage and the drainage pattern maintained the natural state.From the Han(121 BC-220)to the Wei-Jin Dynasties(220-316),the utilization of water resources intensified unprecedentedly,but the natural shape of the river systems was still maintained.In the following 1,000 years or so,the drainage pattern was in the state of“following its own course”due to the small human population.In the Ming Dynasty(1368-1644),with the alteration of the main rivers,the water resource utilization increased obviously,but the human reclamations were mainly confined to the southern part of the basin.In the Qing Dynasty(1644-1911),the reclamation of the Liulin Lake area significantly changed the drainage patterns,resulted in the drastically northward expansion of human settlement.Since the foundation of the People’s Republic of China(PRC)in 1949,the artificial water system completely replaced the natural water system and intensified the ecological problems in the basin.Discussion:The changes over the past 2000 years show the drastic impacts of human activities on the alterations of the drainage patterns and related ecological problems in the arid Northwest China.Conclusion:Rehabilitation of such ecological impairments requires both ecological restoration projects and changes in human paradigm and behavior over multiple temporal and spatial scales.
