Ice core δ\{\}\+\{18\}O records from the No.1 glacier at the head of the rümqi River were used to characterize the relationship between δ\{\}\+\{18\}O and contemporaneous surface air temperature (Ta) nearby the...Ice core δ\{\}\+\{18\}O records from the No.1 glacier at the head of the rümqi River were used to characterize the relationship between δ\{\}\+\{18\}O and contemporaneous surface air temperature (Ta) nearby the Daxigou Meteorological Station (3539 m above sea level, ～2km away from the ice core drilling site). Although the ice core records of annually averaged δ\{\}\+\{18\}O are positively correlated with contemporaneous surface air temperature, especially summer air temperature, the correlation is less significant than that for the precipitation samples due to depositional and post\|depositional modification processes. However, the climatological significance of the ice core δ\{\}\+\{18\}O records can be still preserved to a certain degree, which might extend the application of high altitude and sub\|tropical ice core δ\{\}\+\{18\}O records to paleoclimate reconstruction.展开更多
Synoptic patterns identified by an automated procedure employing principal- component analysis and a two-stage cluster analysis, and backward trajectory analysis clustered by the HYSPLIT4.9 model were used to examine ...Synoptic patterns identified by an automated procedure employing principal- component analysis and a two-stage cluster analysis, and backward trajectory analysis clustered by the HYSPLIT4.9 model were used to examine air quality patterns over¨ Uru¨mqi, China, one of the most heavily polluted cities in the world. Six synoptic patterns representing different atmospheric circulation patterns and air-mass characteristics were classified during the winter heating periods from 2001 to 2008, and seven trajectory clusters representing different paths of air masses arriving at ürümqi were calculated during the winter heating periods from 2005 to 2008. Then air quality was evaluated using these two approaches, and significant variations were found across both synoptic patterns and trajectory clusters. The heaviest air-pollution episodes occurred when ürümqi was either in an extremely cold, strong anticyclone or at the front of a migrating cyclone. Both conditions were characterized by with light winds, cold, wet surface air, and relatively dry upper air. ürümqi was predominately influenced by air masses from the southwest and from local areas. Air pollution index （API） levels were highest for air masses originating from the southwest with a longer path or for the local area, because of transport from semi-desert/desert regions by strong winds and because of local heavy pollution emissions, respectively. The interactions between these two analytical approaches showed that poor diffusion conditions, together with local circulation, enhanced air pollution, besides, regional air-mass transport caused by strong winds contributed to serious air quality under relatively good diffusion conditions.展开更多
This study estimated pollutant load from Kahuwa micro-catchment into Lake Kivu. The micro-catchment was sampled monthly for a year at six locations to capture the contribution of agricultural land, industries and comm...This study estimated pollutant load from Kahuwa micro-catchment into Lake Kivu. The micro-catchment was sampled monthly for a year at six locations to capture the contribution of agricultural land, industries and commercial blocks. Both wet and dry depositions in terms of TN （total nitrogen） and TP （total phosphorus） were estimated monthly. The level of pollution was estimated using LISEC index and IPO （organic pollution indices）. Results show that Kahuwa River micro-catchment is polluted mainly by waste dumping sites and industries within the micro-catchment. The general load to the outlet was respectively about 0.35 tons per year （t/yr） for BODs, 1.9 t/yr for COD, 32.73 t/yr for TP and 224.37 t/yr for TN. Atmospheric deposition of nutrient contributed for about 4% and 18% of TP, 3% and 0.01% of TN during dry and wet deposition, respectively.展开更多
In the High Atlas soil erosion constitutes a serious problem which leads to destruction of agricultural land and to the supply of important solid load to streams.This process contributes to harmful floods and to signi...In the High Atlas soil erosion constitutes a serious problem which leads to destruction of agricultural land and to the supply of important solid load to streams.This process contributes to harmful floods and to significant silting of dams.The management of the basins slopes is a priority in order to reduce damage related to erosion.In the studied area,a significant part of the geological formations are展开更多
Rainfall and air temperature data from six meteorological stations above the Bengbu Sluice and hydrological and water resources evaluation data from the Bengbu Hydrological Station in the Huai River Basin from 1961 to...Rainfall and air temperature data from six meteorological stations above the Bengbu Sluice and hydrological and water resources evaluation data from the Bengbu Hydrological Station in the Huai River Basin from 1961 to 2008 are used to analyze the impact of changes in climatic factors on the amount of water resources in the Basin. There was a general trend of rise in its average annual air temperature, with the highest increase of 0.289℃/10a recorded at Bengbu in Anhui Province. Rising rainfall was mainly observed in the western part of the study area, while rainfall actually declined in the eastern part, i.e. the middle reaches of the Huai River. The Average rainfall in the study area was in a vaguely declining trend. In other words, the rainfall in the Basin is still much affected by natural fluctuations. On the whole, there was a trend of gradual decrease in the quantity of the Basin＇s water resources for the period under study. Water resources quantity is found to fall with decreasing rainfall and rising air temperature. Regression analysis is used to establish a mathematical model between water resources quantity and climatic factors （i.e. air temperature and rainfall） in order to explore the impact of climate change on water resources in the Basin. Moreover, various scenarios are set to quantitatively analyze the response of water resources to climate change. Sensitivity analysis shows that changes in rainfall have a much bigger impact on its water resources quantity than changes in its air temperature.展开更多
This paper describes some details and procedural steps in the equivalent resistance （E-R） method for simplifying the pier group of the Sutong Bridge, which is located on the tidal reach of the lower Yangtze River, i...This paper describes some details and procedural steps in the equivalent resistance （E-R） method for simplifying the pier group of the Sutong Bridge, which is located on the tidal reach of the lower Yangtze River, in Jiangsu Province. Using a two-dimensional tidal current numerical model, three different models were established： the non-bridge pier model, original bridge pier model, and simplified bridge pier model. The difference in hydrodynamic parameters, including water level, velocity, and diversion ratio, as well as time efficiency between these three models is discussed in detail. The results show that simplifying the pier group using the E-R method influences the water level and velocity near the piers, but has no influence on the diversion ratio of each cross-section of the Xuliujing reach located in the lower Yangtze River. Furthermore, the simplified bridge pier model takes half the calculation time that the original bridge pier model needs. Thus, it is concluded that the E-R method can be use to simplify bridge piers in tidal river section modeling reasonably and efficiently.展开更多
文摘Ice core δ\{\}\+\{18\}O records from the No.1 glacier at the head of the rümqi River were used to characterize the relationship between δ\{\}\+\{18\}O and contemporaneous surface air temperature (Ta) nearby the Daxigou Meteorological Station (3539 m above sea level, ～2km away from the ice core drilling site). Although the ice core records of annually averaged δ\{\}\+\{18\}O are positively correlated with contemporaneous surface air temperature, especially summer air temperature, the correlation is less significant than that for the precipitation samples due to depositional and post\|depositional modification processes. However, the climatological significance of the ice core δ\{\}\+\{18\}O records can be still preserved to a certain degree, which might extend the application of high altitude and sub\|tropical ice core δ\{\}\+\{18\}O records to paleoclimate reconstruction.
基金supported by the National Basic Research Program (also called 973 Program) of China (Grant No 2007CB407303)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No KZCX2-YW-Q02-03)
文摘Synoptic patterns identified by an automated procedure employing principal- component analysis and a two-stage cluster analysis, and backward trajectory analysis clustered by the HYSPLIT4.9 model were used to examine air quality patterns over¨ Uru¨mqi, China, one of the most heavily polluted cities in the world. Six synoptic patterns representing different atmospheric circulation patterns and air-mass characteristics were classified during the winter heating periods from 2001 to 2008, and seven trajectory clusters representing different paths of air masses arriving at ürümqi were calculated during the winter heating periods from 2005 to 2008. Then air quality was evaluated using these two approaches, and significant variations were found across both synoptic patterns and trajectory clusters. The heaviest air-pollution episodes occurred when ürümqi was either in an extremely cold, strong anticyclone or at the front of a migrating cyclone. Both conditions were characterized by with light winds, cold, wet surface air, and relatively dry upper air. ürümqi was predominately influenced by air masses from the southwest and from local areas. Air pollution index （API） levels were highest for air masses originating from the southwest with a longer path or for the local area, because of transport from semi-desert/desert regions by strong winds and because of local heavy pollution emissions, respectively. The interactions between these two analytical approaches showed that poor diffusion conditions, together with local circulation, enhanced air pollution, besides, regional air-mass transport caused by strong winds contributed to serious air quality under relatively good diffusion conditions.
文摘This study estimated pollutant load from Kahuwa micro-catchment into Lake Kivu. The micro-catchment was sampled monthly for a year at six locations to capture the contribution of agricultural land, industries and commercial blocks. Both wet and dry depositions in terms of TN （total nitrogen） and TP （total phosphorus） were estimated monthly. The level of pollution was estimated using LISEC index and IPO （organic pollution indices）. Results show that Kahuwa River micro-catchment is polluted mainly by waste dumping sites and industries within the micro-catchment. The general load to the outlet was respectively about 0.35 tons per year （t/yr） for BODs, 1.9 t/yr for COD, 32.73 t/yr for TP and 224.37 t/yr for TN. Atmospheric deposition of nutrient contributed for about 4% and 18% of TP, 3% and 0.01% of TN during dry and wet deposition, respectively.
文摘In the High Atlas soil erosion constitutes a serious problem which leads to destruction of agricultural land and to the supply of important solid load to streams.This process contributes to harmful floods and to significant silting of dams.The management of the basins slopes is a priority in order to reduce damage related to erosion.In the studied area,a significant part of the geological formations are
基金supported by the National Natural Sciences Foundation of China (Project Nos. 51079132 and 50679075)the Special Research Fund Project of the Chinese Ministry of Water Resources (Grant No. 200801001)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20094101110002)the National Key Scientific and Technological Project on Water Pollution Control and Treatment of China (Project No. 2009ZX07210-006)
文摘Rainfall and air temperature data from six meteorological stations above the Bengbu Sluice and hydrological and water resources evaluation data from the Bengbu Hydrological Station in the Huai River Basin from 1961 to 2008 are used to analyze the impact of changes in climatic factors on the amount of water resources in the Basin. There was a general trend of rise in its average annual air temperature, with the highest increase of 0.289℃/10a recorded at Bengbu in Anhui Province. Rising rainfall was mainly observed in the western part of the study area, while rainfall actually declined in the eastern part, i.e. the middle reaches of the Huai River. The Average rainfall in the study area was in a vaguely declining trend. In other words, the rainfall in the Basin is still much affected by natural fluctuations. On the whole, there was a trend of gradual decrease in the quantity of the Basin＇s water resources for the period under study. Water resources quantity is found to fall with decreasing rainfall and rising air temperature. Regression analysis is used to establish a mathematical model between water resources quantity and climatic factors （i.e. air temperature and rainfall） in order to explore the impact of climate change on water resources in the Basin. Moreover, various scenarios are set to quantitatively analyze the response of water resources to climate change. Sensitivity analysis shows that changes in rainfall have a much bigger impact on its water resources quantity than changes in its air temperature.
基金supported by the Innovation Project of Graduate Education in Jiangsu Province during 2011 (Grant No. CXZZ11_0449)the Research Plan Project of Transportation Science in Jiangsu Province (Grant No. 20100714-30HDKY001-2)
文摘This paper describes some details and procedural steps in the equivalent resistance （E-R） method for simplifying the pier group of the Sutong Bridge, which is located on the tidal reach of the lower Yangtze River, in Jiangsu Province. Using a two-dimensional tidal current numerical model, three different models were established： the non-bridge pier model, original bridge pier model, and simplified bridge pier model. The difference in hydrodynamic parameters, including water level, velocity, and diversion ratio, as well as time efficiency between these three models is discussed in detail. The results show that simplifying the pier group using the E-R method influences the water level and velocity near the piers, but has no influence on the diversion ratio of each cross-section of the Xuliujing reach located in the lower Yangtze River. Furthermore, the simplified bridge pier model takes half the calculation time that the original bridge pier model needs. Thus, it is concluded that the E-R method can be use to simplify bridge piers in tidal river section modeling reasonably and efficiently.
