The Fraser River delta in Greater Vancouver, Canada consists of deep soft deposits of silts and clays, and it is well known that the deep soil deposits can amplify the low frequency contents of ground motions. This st...The Fraser River delta in Greater Vancouver, Canada consists of deep soft deposits of silts and clays, and it is well known that the deep soil deposits can amplify the low frequency contents of ground motions. This study aims to investigate the eff ects of deep soil deposits in the delta on ground motion amplifi cations by using thorough site response simulations that account for the full soil profi les and a suite of recorded ground motions that covers a wide range of intensity levels. Based on both equivalent-linear and nonlinear site response simulations, the eff ects of soil depth (represented by natural period of the soil, TS) on ground motion amplifi cations for various spectral periods are clearly demonstrated. The ground motion amplifi cation maps for various spectral periods and rock ground motion intensity levels are also generated to be used in the regional seismic hazard assessment for infrastructure. It is found that ground motions for long periods are substantially amplifi ed in the center of the delta, while those for short periods are de-amplifi ed when input rock motions are large.展开更多
The main purpose of the research is to discuss the influence on ground water by NH4-N in polluted river and river bed.In the lab-scale experiment three kinds of natural sand were chosen as infiltration medium,and poll...The main purpose of the research is to discuss the influence on ground water by NH4-N in polluted river and river bed.In the lab-scale experiment three kinds of natural sand were chosen as infiltration medium,and polluted rivers were simulated by domestic sewage,after 10-month sand column test it was found that NH_4-N came to adsorption sa- turation on the 17th day in coarse sand and on the 130～140th day in medium sand,then had a higher effluent concentration because of desorption.It is concluded that NH_4-N eas- ily moved to ground water.When the concentration of NH_4-N in Liangshui River were 46.86,26.95 mg/L,that in groundwater are less than 1.10 mg/L.It is found that Liangshui River have a little influence on groundwater because of bottom mud,thickness and char- acter of the infiltration medium under the river bed and seepage quantity of river water. Clean water leaching test states that after the silt is cleared away and clean water is poured,NH_4-N in the penetration media under the polluted river is obviously carried into ground water,and ground water is polluted secondly.展开更多
Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating...Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating spring, summer, autumn and winter air temperatures and mean annual air temperature（MAAT） from 1960 through 2008 over the Heihe River Basin reveals a statistically significant trend of 0.31 °C/decade, 0.28 °C/decade, 0.37 °C/decade, 0.50 °C/decade, and 0.37 °C /decade, respectively. The averaged time series of mean annual ground surface temperature（MAGST） and maximum annual ground surface temperature（MaxAGST） for 1972–2006 over the basin indicates a statistically significant trend of 0.58 °C/decade and 1.27 °C/decade, respectively. The minimum annual ground surface temperature（MinAGST） in the same period remains unchanged as a whole. Estimating surface freezing/thawing index as well as the ratio of freezing index to thawing index（RFT） in the period between 1959 and 2006 over the basin indicates a statistically significant trend of-42.5 °C-day/decade, 85.4 °C-day/decade and-0.018/decade, respectively.展开更多
Investigation on spatiotemporal variations of maximum seasonal freeze depth （MSFD） over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecologi...Investigation on spatiotemporal variations of maximum seasonal freeze depth （MSFD） over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecological-hydrological processes, water resources assessment, construction and resource development. Based on soil and air temperatures at the meteorological stations of the China Meteorological Administration （CMA） over the Heihe River Basin, MSFDs time series are structured into a composite time series over the 1960-2007 period. Evaluating the averaged MSFD time series for 1960 2007 reveals a statistically significant trend of 4.0 cm/decade or a net change of-19.2 cm for the 48-year period over the basin. The MSFD had significantly negative correlation with mean annual air temperature （MAAT）, winter air temperature, mean annual ground surface temperature （MAGST）, degree days of thawing for the air （DDTa） as well as for the surface （DDTs）, and degree days of freezing for the surface （DDFs）. While there was significantly positive correlation between DDF,. and MSFD time series, MSFD was deeper and changed greatly in the Heihe River source area. It was shallower in the east-central basin and gradually deepened in other sections of the basin. The MSFD distribution pattern in 2003-2005 is consistent with that of averaged degree days of freezing for air （DDFa） in 1960-2007. However, the maximum of MSFD may not be accurate, because there is no long term observation data in the deep seasonally frozen ground regions near the lower boundary of permafrost. With increasing elevation, averaged DDFa increased at a rate of 51.6 ℃-day/100m, therefore, the MSFG and the date reaching MSFG became deeper and later, respectively.展开更多
This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolatin...This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolating functions,and non-linear regression methods.The source regions of the Yangtze and Yellow Rivers were selected as the research areas.Results illustrate that:(1) There is significant non-linear relationship between NPP and GT in various typical years;(2) The maximum value of NPP is 6.17,5.87,7.73,and 5.41 DM·t·hm-2 ·a-1 respectively,and the corresponding GT is 7.1,10.0,21.2,and 8.9 o C respectively in 1980,1990,2000 and 2007;(3) In 1980,the sensitivity of NPP to GT is higher than in 1990,2000 and 2007.This tendency shows that the NPP presents change from fluctuation to an adaptation process over time;(4) During 1980～2007,the accumulated NPP was reduced to 8.05,and the corresponding carrying capacity of theoretical livestock reduced by 11%;(5) The shape of the demonstration region of ecological compensation system,livelihood support system,and science appraisal system in the source regions of Yangtze and Yellow Rivers are an important research for increasing the adaptation capacity and balancing protection and development.展开更多
基金2018 Research Fund(1.170059.01)of UNIST(Ulsan National Institute of Science and Technology)the National Research Foundation of Korea(NRF)with a grant from the Korean government(MSIT)(NRF-2017R1C1B5074430)
文摘The Fraser River delta in Greater Vancouver, Canada consists of deep soft deposits of silts and clays, and it is well known that the deep soil deposits can amplify the low frequency contents of ground motions. This study aims to investigate the eff ects of deep soil deposits in the delta on ground motion amplifi cations by using thorough site response simulations that account for the full soil profi les and a suite of recorded ground motions that covers a wide range of intensity levels. Based on both equivalent-linear and nonlinear site response simulations, the eff ects of soil depth (represented by natural period of the soil, TS) on ground motion amplifi cations for various spectral periods are clearly demonstrated. The ground motion amplifi cation maps for various spectral periods and rock ground motion intensity levels are also generated to be used in the regional seismic hazard assessment for infrastructure. It is found that ground motions for long periods are substantially amplifi ed in the center of the delta, while those for short periods are de-amplifi ed when input rock motions are large.
基金the National Natural Science Foundation of China(40772165)
文摘The main purpose of the research is to discuss the influence on ground water by NH4-N in polluted river and river bed.In the lab-scale experiment three kinds of natural sand were chosen as infiltration medium,and polluted rivers were simulated by domestic sewage,after 10-month sand column test it was found that NH_4-N came to adsorption sa- turation on the 17th day in coarse sand and on the 130～140th day in medium sand,then had a higher effluent concentration because of desorption.It is concluded that NH_4-N eas- ily moved to ground water.When the concentration of NH_4-N in Liangshui River were 46.86,26.95 mg/L,that in groundwater are less than 1.10 mg/L.It is found that Liangshui River have a little influence on groundwater because of bottom mud,thickness and char- acter of the infiltration medium under the river bed and seepage quantity of river water. Clean water leaching test states that after the silt is cleared away and clean water is poured,NH_4-N in the penetration media under the polluted river is obviously carried into ground water,and ground water is polluted secondly.
基金supported by the Chinese Academy of Sciences Key Research Program (No. KZZD-EW-13)the Natural Science Foundation of China (Nos. 91025013, 91325202)+1 种基金the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZY-06), CASthe Major Research Plan of the National Natural Science Foundation of China (No. 2013CBA01802)
文摘Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating spring, summer, autumn and winter air temperatures and mean annual air temperature（MAAT） from 1960 through 2008 over the Heihe River Basin reveals a statistically significant trend of 0.31 °C/decade, 0.28 °C/decade, 0.37 °C/decade, 0.50 °C/decade, and 0.37 °C /decade, respectively. The averaged time series of mean annual ground surface temperature（MAGST） and maximum annual ground surface temperature（MaxAGST） for 1972–2006 over the basin indicates a statistically significant trend of 0.58 °C/decade and 1.27 °C/decade, respectively. The minimum annual ground surface temperature（MinAGST） in the same period remains unchanged as a whole. Estimating surface freezing/thawing index as well as the ratio of freezing index to thawing index（RFT） in the period between 1959 and 2006 over the basin indicates a statistically significant trend of-42.5 °C-day/decade, 85.4 °C-day/decade and-0.018/decade, respectively.
基金supported by the Global Change Research Program of China (No. 2010CB951402)the Natural Science Foundation of China (Nos. 91025013, 91325202)+1 种基金the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZY-06), CAS, Chinathe Major Research Plan of the Natural Science Foundation of China (No. 2013CBA01802)
文摘Investigation on spatiotemporal variations of maximum seasonal freeze depth （MSFD） over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecological-hydrological processes, water resources assessment, construction and resource development. Based on soil and air temperatures at the meteorological stations of the China Meteorological Administration （CMA） over the Heihe River Basin, MSFDs time series are structured into a composite time series over the 1960-2007 period. Evaluating the averaged MSFD time series for 1960 2007 reveals a statistically significant trend of 4.0 cm/decade or a net change of-19.2 cm for the 48-year period over the basin. The MSFD had significantly negative correlation with mean annual air temperature （MAAT）, winter air temperature, mean annual ground surface temperature （MAGST）, degree days of thawing for the air （DDTa） as well as for the surface （DDTs）, and degree days of freezing for the surface （DDFs）. While there was significantly positive correlation between DDF,. and MSFD time series, MSFD was deeper and changed greatly in the Heihe River source area. It was shallower in the east-central basin and gradually deepened in other sections of the basin. The MSFD distribution pattern in 2003-2005 is consistent with that of averaged degree days of freezing for air （DDFa） in 1960-2007. However, the maximum of MSFD may not be accurate, because there is no long term observation data in the deep seasonally frozen ground regions near the lower boundary of permafrost. With increasing elevation, averaged DDFa increased at a rate of 51.6 ℃-day/100m, therefore, the MSFG and the date reaching MSFG became deeper and later, respectively.
基金supported by the National Basic Research Program of China (973 Program,Grant No. 2007CB411507 and Grant No.2010CB951704)
文摘This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolating functions,and non-linear regression methods.The source regions of the Yangtze and Yellow Rivers were selected as the research areas.Results illustrate that:(1) There is significant non-linear relationship between NPP and GT in various typical years;(2) The maximum value of NPP is 6.17,5.87,7.73,and 5.41 DM·t·hm-2 ·a-1 respectively,and the corresponding GT is 7.1,10.0,21.2,and 8.9 o C respectively in 1980,1990,2000 and 2007;(3) In 1980,the sensitivity of NPP to GT is higher than in 1990,2000 and 2007.This tendency shows that the NPP presents change from fluctuation to an adaptation process over time;(4) During 1980～2007,the accumulated NPP was reduced to 8.05,and the corresponding carrying capacity of theoretical livestock reduced by 11%;(5) The shape of the demonstration region of ecological compensation system,livelihood support system,and science appraisal system in the source regions of Yangtze and Yellow Rivers are an important research for increasing the adaptation capacity and balancing protection and development.
