Gezhouba hydroproject was impounded and put into operation in 1981. In order to analyse the impact on the downstream river course, Jingjiang Hydrologic and Water Resources Survey Bureau of Changjiang Water Resources C...Gezhouba hydroproject was impounded and put into operation in 1981. In order to analyse the impact on the downstream river course, Jingjiang Hydrologic and Water Resources Survey Bureau of Changjiang Water Resources Commission has conducted prototype observation on the Yichang-Chenglingji river stretch. On basis of the observed data, the change in river regime and scour-sedimentation evolution and water surface profile below the dam are analysed systematically. The results show that the scouring of downstream river course mainly stretches from Yichang to Ouchikou, mainly occurring in 1980～1987; the scourring mainly takes place in the river channel and the water surface profile drops significantly in dry season,but not quite in high flood season.展开更多
Coastal seas,located between continents and the open ocean,are an important active carbon pool.The sedimentary total organic carbon(TOC)in these areas is a mixture of terrestrial and marine sources,and can be a powerf...Coastal seas,located between continents and the open ocean,are an important active carbon pool.The sedimentary total organic carbon(TOC)in these areas is a mixture of terrestrial and marine sources,and can be a powerful proxy for tracing natural processes and human activities.In this study,one fine-grained sediment core(DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon(BC) contents and TOC stable carbon isotope ratios(d13 C).By combining these data with 210~Pb dating,an improved carbon correction model and a two end-member mixing model,we reconstructed century-scale high-resolution sequences of corrected TOC,terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record.The two events,shown as two minima in the TOC profiles,correspond temporally to 1985-1987 AD and 2003-2006 AD,which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam,respectively.In addition,the variations in TOC contents and δ^(13)C values before,during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River.The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological ef fects on the inner shelf of the East China Sea to the water impoundment of the dams.These new TOC records reflect the interaction between natural and anthropogenic processes and,accordingly,provide a deep insight and important references for assessing marine ecological ef fects resulting from water impoundment of largescale dams.展开更多
Almost at every mouth of the tributary creek of the Three Gorges inthe Gezhouba Reservoir, the alluvial fans or alluvial cones formed the rapids, whichare called rapids of creek mouth--bar. They are composed of pebble...Almost at every mouth of the tributary creek of the Three Gorges inthe Gezhouba Reservoir, the alluvial fans or alluvial cones formed the rapids, whichare called rapids of creek mouth--bar. They are composed of pebble bed load with d>20 mm. Based upon geological and geomorphological investigations, the authors detect that the pebble bed load at the Gezhouba Re3ervoir comes from two sources,namely, the region mainly with limestone and The region mainly with pyrolith, andtheir converging area is within the Gezhouba Project. percentages of the pebble bedload are calculated. The calculated result stows that, 65% of pebble bed load comesfrom the region mainly with limestone, and 93 % of the rapids of creek mouth--bar isdistributed in the region mainly with limestone. Considering the water level fluctuations, the rapids of creek mouth--bar can be divided into 3 types i. e. flood waterones, medium water ones and low water ones. Due to the rise of water level afterbuilding the Gezhouba Reservoir, the navigable channels in the area of rapids ofcreek mouth--bar within varied back water region are improved, taking up 50% of all12 rapids. But the rapids of creek mouth--bar in the tail region where the water levelrises less than 1 m, the conditions of navigable channels are little improved and evendeterioration, because of the continuous supply of pebble bed load. Therefore, thoserapids must be regulated before the completion of the Three Gorges Project.展开更多
Yichang City is the place where both the Three Gorges and the Gezhouba Dam projects are being constructed. Practice shows that any large State planned project will bring prosperity to the local economy. The Gezhouba D...Yichang City is the place where both the Three Gorges and the Gezhouba Dam projects are being constructed. Practice shows that any large State planned project will bring prosperity to the local economy. The Gezhouba Dam Project in Yichang has provided the first opportunity for the city’s development During the first stage of the Gezhouba project from 1971 to 1980, the annual average progressive growth rate of fixed assets investment and展开更多
The Gezhouba water conservancy project includes the first and largest hydropower station on the Yangtze River. The dam is 2606.5 metres long and 70 metres high with a water drop of 27 metres. Like a monster dragon lyi...The Gezhouba water conservancy project includes the first and largest hydropower station on the Yangtze River. The dam is 2606.5 metres long and 70 metres high with a water drop of 27 metres. Like a monster dragon lying at the outlet of the Xilin Gorge of the river, this spectacular dam blockades the east-running torrents and made them a source of money.展开更多
It is the presence of weakened intercalations that makes the foundation of Gezhouba Erjiang-Sluice complex. Seepage control installation must be able not only to reduce seepapge pressure, but also to protect weakened ...It is the presence of weakened intercalations that makes the foundation of Gezhouba Erjiang-Sluice complex. Seepage control installation must be able not only to reduce seepapge pressure, but also to protect weakened intercalations from encroachment of seepage. In this paper theoretical analysis has been conducted to prove that well system is highly effective seepage control installation meeting this demand. By means of in-situ monitoring it has been verified that proposed seepage control measure relying mainly on drainage is of success. Seepage stability of weakened intercalations must be considered in employing drains to control seepage, while the seepage deformation of weakened intercalations is different from that of ordinary sand-gravel. Mechanism of seepage deformation of weakened intercalations has been expounded. Seepage wedging is a special type of seepage deformation for weakened intercalations, It is shown clearly that seepage deformation of intercalations does not mean seepage failure of the foundation. In such a foundation as that of Gezhouba sluice, the permeability is distributed randomly. So the seepage field is an unstable, stochastic field.展开更多
文摘Gezhouba hydroproject was impounded and put into operation in 1981. In order to analyse the impact on the downstream river course, Jingjiang Hydrologic and Water Resources Survey Bureau of Changjiang Water Resources Commission has conducted prototype observation on the Yichang-Chenglingji river stretch. On basis of the observed data, the change in river regime and scour-sedimentation evolution and water surface profile below the dam are analysed systematically. The results show that the scouring of downstream river course mainly stretches from Yichang to Ouchikou, mainly occurring in 1980～1987; the scourring mainly takes place in the river channel and the water surface profile drops significantly in dry season,but not quite in high flood season.
基金Supported by the National Basic Research Program of China(973 Program)(No.2012CB956004)the Fundamental Research Funds for the Central Universities(No.16lgjc22)
文摘Coastal seas,located between continents and the open ocean,are an important active carbon pool.The sedimentary total organic carbon(TOC)in these areas is a mixture of terrestrial and marine sources,and can be a powerful proxy for tracing natural processes and human activities.In this study,one fine-grained sediment core(DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon(BC) contents and TOC stable carbon isotope ratios(d13 C).By combining these data with 210~Pb dating,an improved carbon correction model and a two end-member mixing model,we reconstructed century-scale high-resolution sequences of corrected TOC,terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record.The two events,shown as two minima in the TOC profiles,correspond temporally to 1985-1987 AD and 2003-2006 AD,which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam,respectively.In addition,the variations in TOC contents and δ^(13)C values before,during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River.The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological ef fects on the inner shelf of the East China Sea to the water impoundment of the dams.These new TOC records reflect the interaction between natural and anthropogenic processes and,accordingly,provide a deep insight and important references for assessing marine ecological ef fects resulting from water impoundment of largescale dams.
文摘Almost at every mouth of the tributary creek of the Three Gorges inthe Gezhouba Reservoir, the alluvial fans or alluvial cones formed the rapids, whichare called rapids of creek mouth--bar. They are composed of pebble bed load with d>20 mm. Based upon geological and geomorphological investigations, the authors detect that the pebble bed load at the Gezhouba Re3ervoir comes from two sources,namely, the region mainly with limestone and The region mainly with pyrolith, andtheir converging area is within the Gezhouba Project. percentages of the pebble bedload are calculated. The calculated result stows that, 65% of pebble bed load comesfrom the region mainly with limestone, and 93 % of the rapids of creek mouth--bar isdistributed in the region mainly with limestone. Considering the water level fluctuations, the rapids of creek mouth--bar can be divided into 3 types i. e. flood waterones, medium water ones and low water ones. Due to the rise of water level afterbuilding the Gezhouba Reservoir, the navigable channels in the area of rapids ofcreek mouth--bar within varied back water region are improved, taking up 50% of all12 rapids. But the rapids of creek mouth--bar in the tail region where the water levelrises less than 1 m, the conditions of navigable channels are little improved and evendeterioration, because of the continuous supply of pebble bed load. Therefore, thoserapids must be regulated before the completion of the Three Gorges Project.
文摘Yichang City is the place where both the Three Gorges and the Gezhouba Dam projects are being constructed. Practice shows that any large State planned project will bring prosperity to the local economy. The Gezhouba Dam Project in Yichang has provided the first opportunity for the city’s development During the first stage of the Gezhouba project from 1971 to 1980, the annual average progressive growth rate of fixed assets investment and
文摘The Gezhouba water conservancy project includes the first and largest hydropower station on the Yangtze River. The dam is 2606.5 metres long and 70 metres high with a water drop of 27 metres. Like a monster dragon lying at the outlet of the Xilin Gorge of the river, this spectacular dam blockades the east-running torrents and made them a source of money.
文摘It is the presence of weakened intercalations that makes the foundation of Gezhouba Erjiang-Sluice complex. Seepage control installation must be able not only to reduce seepapge pressure, but also to protect weakened intercalations from encroachment of seepage. In this paper theoretical analysis has been conducted to prove that well system is highly effective seepage control installation meeting this demand. By means of in-situ monitoring it has been verified that proposed seepage control measure relying mainly on drainage is of success. Seepage stability of weakened intercalations must be considered in employing drains to control seepage, while the seepage deformation of weakened intercalations is different from that of ordinary sand-gravel. Mechanism of seepage deformation of weakened intercalations has been expounded. Seepage wedging is a special type of seepage deformation for weakened intercalations, It is shown clearly that seepage deformation of intercalations does not mean seepage failure of the foundation. In such a foundation as that of Gezhouba sluice, the permeability is distributed randomly. So the seepage field is an unstable, stochastic field.
