Hourly summer precipitation data recorded at 21 stations during 1961-2004 in the Haihe River Basin in North China were an alyzed. The results show that the precipitation frequency and amount and the morning peak mainl...Hourly summer precipitation data recorded at 21 stations during 1961-2004 in the Haihe River Basin in North China were an alyzed. The results show that the precipitation frequency and amount and the morning peak mainly relating to longduratiol rainfall events decreased during this period, whereas the normalized afternoon peak mainly relating to short-duration event： increased, which may suggest that the proportion of short-duration rainfall has increased as the total summer rainfall has de creased. For short-duration events, the mean intensity and peak intensity increased at most stations and the time to peak inten sity decreased, which may be attributable to the higher thermal contrast between the warmer lower surface and cooler uppe level. In the case of long-duration events, the total amount was significantly correlated with the East Asian summer monsool index for the period 1961-2001 （correlation coefficient of 0.63）. Although the total amount of rainfall in long-duration event： decreased in the basin, the mean intensity and peak intensity, as well as the extreme hourly precipitation, increased in the western basin and decreased in the eastern basin.展开更多
The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East Chin...The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East China Sea are discussed . The estuarine and coastal waters in the East China Sea were heavily fertilized by the inflow of nutrient-rich freshwater from the Changjiang River, which has led to severe eutrophication and frequent harmful algal blooms ,thus worsening the ecosystem health in this area. Analy- sis showed that the nutrient loadings are very likely to be reduced in the lower Changjiang River due to the construction of Three Gorges Dam. Especially for the total phosphorus, the discharges to the East China Sea will be reduced by one-third, which would relieve the severe eutrophication in this area. However, the expected decrease in the riverine silicate discharge would lead the ratio of silicon to nitrogen to be much less than 1 in the estuarine and coastal waters and thus may cause an elevation of flagellate growth. The changes in the annual water discharges and their seasonal distributions below the dam will be minor. Reduction of suspended particulate matter loading, due to the sedimentation behind the dam, will reduce the nutrient loadings of the particulate form especially for phosphorus, and decrease the turbidity of estuarine and coastal waters. On the other hand, this may enhance the erosion of the delta and the coasts as well as modifythe benthic ecosystem.展开更多
The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary l...The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting （Lake ED） during a 35-year study period （1980-2014）. Specifically, we investigated Lake ED＇s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge abil- ity under different hydrologic conditions of the Changjiang River. The results show that （1） the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m3/s in Changjiang River＇s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. （2） Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED.展开更多
As the link connecting the South China Continent and the northern South China Sea(SCS),the Pearl River is the focus of sedimentology and petroleum geology research.Its evolutionary process and controlling factors are ...As the link connecting the South China Continent and the northern South China Sea(SCS),the Pearl River is the focus of sedimentology and petroleum geology research.Its evolutionary process and controlling factors are of great significance in revealing the East Asian continental landscape reorganization during the Late Cenozoic.Based on published data,’source-to-sink’provenance analyses allow systematic deliberation on the birth and evolutionary history of the Pearl River.Close to the Oligocene/Miocene boundary,an abrupt shift in the sedimentary composition indicates significant westward and northward expansion of the river’s watershed area,followed by the establishment of a near-modern fluvial network.This sedimentary change generally concurred with a series of regional geological events,including the onset of the Yangtze throughflow,large-scale development of the loess plateau,and formation of the northwestern arid zone and Asian Monsoon system.These major changes in the geology-climate-ecoenvironment system are in close response to the process of the Cenozoic Xizang(Tibetan)Plateau uplift.Consequently,the East Asian continental landscape and most of midCenozoic drainage systems underwent critical reversion into east-tilting,or east-flowing networks.展开更多
基金supported by the National Basic Research Program of China (Grant No. 2006CB403404)the National Key Technology R&D Program of China (Grant No. 2007 BAC29B04)the National Science Foundation Program for Post-doctoral Scientists of China (Grant No. 20080440343)
文摘Hourly summer precipitation data recorded at 21 stations during 1961-2004 in the Haihe River Basin in North China were an alyzed. The results show that the precipitation frequency and amount and the morning peak mainly relating to longduratiol rainfall events decreased during this period, whereas the normalized afternoon peak mainly relating to short-duration event： increased, which may suggest that the proportion of short-duration rainfall has increased as the total summer rainfall has de creased. For short-duration events, the mean intensity and peak intensity increased at most stations and the time to peak inten sity decreased, which may be attributable to the higher thermal contrast between the warmer lower surface and cooler uppe level. In the case of long-duration events, the total amount was significantly correlated with the East Asian summer monsool index for the period 1961-2001 （correlation coefficient of 0.63）. Although the total amount of rainfall in long-duration event： decreased in the basin, the mean intensity and peak intensity, as well as the extreme hourly precipitation, increased in the western basin and decreased in the eastern basin.
基金The National Key Basic Research Program of Ministry of Science and Technology of China under contract No.2001CB4097the Foundation of Key Laboratory of Marine Ecosystem and Biogeochemistry of State Oceanic Administration of China under contract No.LMEB200603.
文摘The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East China Sea are discussed . The estuarine and coastal waters in the East China Sea were heavily fertilized by the inflow of nutrient-rich freshwater from the Changjiang River, which has led to severe eutrophication and frequent harmful algal blooms ,thus worsening the ecosystem health in this area. Analy- sis showed that the nutrient loadings are very likely to be reduced in the lower Changjiang River due to the construction of Three Gorges Dam. Especially for the total phosphorus, the discharges to the East China Sea will be reduced by one-third, which would relieve the severe eutrophication in this area. However, the expected decrease in the riverine silicate discharge would lead the ratio of silicon to nitrogen to be much less than 1 in the estuarine and coastal waters and thus may cause an elevation of flagellate growth. The changes in the annual water discharges and their seasonal distributions below the dam will be minor. Reduction of suspended particulate matter loading, due to the sedimentation behind the dam, will reduce the nutrient loadings of the particulate form especially for phosphorus, and decrease the turbidity of estuarine and coastal waters. On the other hand, this may enhance the erosion of the delta and the coasts as well as modifythe benthic ecosystem.
基金Key Research Program of the Chinese Academy of Sciences,No.KFZD-SW-318National Basic Research Program of China,No.2012CB417006National Natural Science Foundation of China,No.41601041
文摘The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting （Lake ED） during a 35-year study period （1980-2014）. Specifically, we investigated Lake ED＇s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge abil- ity under different hydrologic conditions of the Changjiang River. The results show that （1） the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m3/s in Changjiang River＇s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. （2） Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED.
基金supported by the National Natural Science Foundation of China(grant Nos.42076066,92055203 and 41874076)the National Science and Technology Major Project of China(grant No.2016ZX05026004-002)the National Key Research and Development Program of China(grant No.2018YFE0202400)。
文摘As the link connecting the South China Continent and the northern South China Sea(SCS),the Pearl River is the focus of sedimentology and petroleum geology research.Its evolutionary process and controlling factors are of great significance in revealing the East Asian continental landscape reorganization during the Late Cenozoic.Based on published data,’source-to-sink’provenance analyses allow systematic deliberation on the birth and evolutionary history of the Pearl River.Close to the Oligocene/Miocene boundary,an abrupt shift in the sedimentary composition indicates significant westward and northward expansion of the river’s watershed area,followed by the establishment of a near-modern fluvial network.This sedimentary change generally concurred with a series of regional geological events,including the onset of the Yangtze throughflow,large-scale development of the loess plateau,and formation of the northwestern arid zone and Asian Monsoon system.These major changes in the geology-climate-ecoenvironment system are in close response to the process of the Cenozoic Xizang(Tibetan)Plateau uplift.Consequently,the East Asian continental landscape and most of midCenozoic drainage systems underwent critical reversion into east-tilting,or east-flowing networks.
