Climate change and Land Use/Cover Change（LUCC） have been identified as two primary factors affecting watershed hydrological regime. This study analyzed the trends of streamflow, precipitation, air temperature and po...Climate change and Land Use/Cover Change（LUCC） have been identified as two primary factors affecting watershed hydrological regime. This study analyzed the trends of streamflow, precipitation, air temperature and potential evapotranspiration（PET） from 1962 to 2008 in the Jihe watershed in northwestern Loess Plateau of China using the Mann-Kendall test. The streamflow responses to climate change and LUCC were quantified independently by the elasticity method. The results show that the streamflow presented a dramatic decline with a turning point occurred in 1971, while the precipitation and PET did not change significantly. The results also show that the temperature rose markedly especially since 1990 s with an approximate increase of 1.74°C over the entire research period（1962–2008）. Using land use transition matrix, we found that slope cropland was significantly converted to terrace between 1970 s and 1990 s and that forest cover increased relatively significantly because of the Grain for Green Project after 2000. The streamflow reduction was predominantly caused by LUCC and its contribution reached up to 90.2%, while the contribution of climate change to streamflow decline was only 9.8%. Although the analytical results between the elasticity method and linear regression model were not satisfactorily consistent, they both indicated that LUCC（human activity） was the major factor causing streamflow decline in the Jihe watershed from 1962 to 2008.展开更多
Purpose:To perform ophthalmic examinations to evaluate the ocular characteristics of children living in the Tibet plateau and diagnosed with congenital heart disease.Methods:.Children with congenital heart disease und...Purpose:To perform ophthalmic examinations to evaluate the ocular characteristics of children living in the Tibet plateau and diagnosed with congenital heart disease.Methods:.Children with congenital heart disease underwent a conventional ocular examination including distant acuity test,slit-lamp examination,.fundus examination,.non-contact intraocular pressure measurement,.measurement of corneal thickness, and fundus photography.Results: Forty-two Tibetan children, aged between 4 and 18 years and diagnosed with congenital heart disease,.were enrolled in this study..The percentage of low visual acuity was4.76%, mean intraocular pressure was(13.67±2.15) mm Hg,average corneal thickness was(492.55±33.79) μm,.96.43%had an anterior chamber depth of 1 / 2 corneal thickness(CT),and 35.7% had an obvious fundus vascular tortuosity.Conclusion:.This study adds to the understanding of the ocular status of the population living in the Tibet plateau, thereby offering clinical evidence for the prevention and treatment of eye diseases in this area.展开更多
Land creation projects have been implemented in China to expand urban space in mountainous areas.In addition to the predictable settlement brought about by filling construction,varying degrees of land subsidence and e...Land creation projects have been implemented in China to expand urban space in mountainous areas.In addition to the predictable settlement brought about by filling construction,varying degrees of land subsidence and engineering failures have a demonstrated relationship to groundwater level fluctuation induced by land creation engineering.In this work,we adopted a typical large-scale land creation project,Yan’an New City in Shaanxi province,West China,as our study area.Prior to conducting the main experiment,preliminary field investigation and groundwater level monitoring were conducted to determine the groundwater fluctuation trend induced by land creation engineering.Although a blind drainage system was implemented,the depth aspect of groundwater level changes after large-scale land creation still needed to be addressed.To study the degree of impact and the settlement mechanism induced by the rising groundwater level,we conducted a Water Immersion Test(WIT)in a typical land creation site for 107 days.The rising groundwater level was simulated by injecting water from the bottom of the filling foundation.During the WIT,the soil water content,surface subsidence,and internal settlement of soil at different depths were obtained.Surface subsidence development could be categorized into four stages during the water level increase.The second stage,which is defined as the point when the groundwater level rises to 10 m,marked the critical point in the process.Furthermore,it was ascertained that the local settlement in regions that were originally composed of steep slopes is larger than that in originally flat areas.In addition,ground cracks and sinkholes in the study area were inspected;and it was determined that they would become new channels that would accelerate water infiltration and exacerbate the settlement.Based on the results from our field investigation and testing,several suggestions are proposed for land creation projects to mitigate issues associated with construction-induced groundwater level rising.展开更多
基金funded by the National Natural Science Foundation of China (41501025, 51609083, 41401038, 51509089)the 2016 Key Scientific Research Projects for Universities of Henan Province (16A170014)
文摘Climate change and Land Use/Cover Change（LUCC） have been identified as two primary factors affecting watershed hydrological regime. This study analyzed the trends of streamflow, precipitation, air temperature and potential evapotranspiration（PET） from 1962 to 2008 in the Jihe watershed in northwestern Loess Plateau of China using the Mann-Kendall test. The streamflow responses to climate change and LUCC were quantified independently by the elasticity method. The results show that the streamflow presented a dramatic decline with a turning point occurred in 1971, while the precipitation and PET did not change significantly. The results also show that the temperature rose markedly especially since 1990 s with an approximate increase of 1.74°C over the entire research period（1962–2008）. Using land use transition matrix, we found that slope cropland was significantly converted to terrace between 1970 s and 1990 s and that forest cover increased relatively significantly because of the Grain for Green Project after 2000. The streamflow reduction was predominantly caused by LUCC and its contribution reached up to 90.2%, while the contribution of climate change to streamflow decline was only 9.8%. Although the analytical results between the elasticity method and linear regression model were not satisfactorily consistent, they both indicated that LUCC（human activity） was the major factor causing streamflow decline in the Jihe watershed from 1962 to 2008.
文摘Purpose:To perform ophthalmic examinations to evaluate the ocular characteristics of children living in the Tibet plateau and diagnosed with congenital heart disease.Methods:.Children with congenital heart disease underwent a conventional ocular examination including distant acuity test,slit-lamp examination,.fundus examination,.non-contact intraocular pressure measurement,.measurement of corneal thickness, and fundus photography.Results: Forty-two Tibetan children, aged between 4 and 18 years and diagnosed with congenital heart disease,.were enrolled in this study..The percentage of low visual acuity was4.76%, mean intraocular pressure was(13.67±2.15) mm Hg,average corneal thickness was(492.55±33.79) μm,.96.43%had an anterior chamber depth of 1 / 2 corneal thickness(CT),and 35.7% had an obvious fundus vascular tortuosity.Conclusion:.This study adds to the understanding of the ocular status of the population living in the Tibet plateau, thereby offering clinical evidence for the prevention and treatment of eye diseases in this area.
基金financial support from National Natural Science Foundation of China (Project No. 41902299 41672305)+2 种基金the Key Science and Technology Program of Shaanxi Province (Project No. 2017ZDXM-SF-078, 2017ZDXM-SF-082)National Key Research and Development Program of China (2018YFC1504700)Shaanxi new-star plan of science and technology (Project No. 2018KJXX020)
文摘Land creation projects have been implemented in China to expand urban space in mountainous areas.In addition to the predictable settlement brought about by filling construction,varying degrees of land subsidence and engineering failures have a demonstrated relationship to groundwater level fluctuation induced by land creation engineering.In this work,we adopted a typical large-scale land creation project,Yan’an New City in Shaanxi province,West China,as our study area.Prior to conducting the main experiment,preliminary field investigation and groundwater level monitoring were conducted to determine the groundwater fluctuation trend induced by land creation engineering.Although a blind drainage system was implemented,the depth aspect of groundwater level changes after large-scale land creation still needed to be addressed.To study the degree of impact and the settlement mechanism induced by the rising groundwater level,we conducted a Water Immersion Test(WIT)in a typical land creation site for 107 days.The rising groundwater level was simulated by injecting water from the bottom of the filling foundation.During the WIT,the soil water content,surface subsidence,and internal settlement of soil at different depths were obtained.Surface subsidence development could be categorized into four stages during the water level increase.The second stage,which is defined as the point when the groundwater level rises to 10 m,marked the critical point in the process.Furthermore,it was ascertained that the local settlement in regions that were originally composed of steep slopes is larger than that in originally flat areas.In addition,ground cracks and sinkholes in the study area were inspected;and it was determined that they would become new channels that would accelerate water infiltration and exacerbate the settlement.Based on the results from our field investigation and testing,several suggestions are proposed for land creation projects to mitigate issues associated with construction-induced groundwater level rising.
