In late May and early June, 2002, a field inves- tigation was conducted along the Three-Gorges valley of the upper Yangtze catchment by ADP (Acoustic Doppler Profile SONTEK-500). Data obtained when surveying were acco...In late May and early June, 2002, a field inves- tigation was conducted along the Three-Gorges valley of the upper Yangtze catchment by ADP (Acoustic Doppler Profile SONTEK-500). Data obtained when surveying were accom- panied with discharge of <15000 m3/s in the valley and char- acterize the unique river-flow velocity profile and riverbed morphology. Taking into consideration the relationship be- tween the average flow velocity and fluvial variables, four distinct river sections can be highlighted, i.e. Chongqing- Wanxian, Wanxian-Fengjie, Fengjie-Zigui and Gezhou res- ervoir area (upstream to downstream). The average flow velocity is in-phase with river width from Chongqing to Wanxian. High-flow velocity ranging from 3.0 to 4.0 m/s is recorded at many sites, where the wider river channel (>1000 m) and shallower water depth (<20 m) occur and large-size gravel shoals prevail. Alternated low-flow velocity (<1.5 m/s) appears at those river sections with deep water (>50 m) and U-shaped river-channel morphology. Mapping the river cross-section area at those sites can determine that smaller cross-section area accelerates the flow velocity. From Wanxian to Fengjie, the average flow velocity ranging from 3.0 to 4.5 m/s is in-phase with the water depth. The high-flow velocity is associated with narrower river-channel, where V-shaped gorges valley occurs with small cross-section area. Further downstream from Fengjie to Zigui, the low flow ve- locity is linked to deep river channel characterized by W-shaped valley morphology of large cross-section area, in general. The average flow velocity is 2.5―3.5 m/s, and maxi- mum can reach 6.0 m/s near Wu-Gorge. Our survey had also detected a slow-flow velocity (mostly <1.0 m/s) in the river channel of about 100 km long in the Gezhou reservoir downstream. Heavy siltation to 20 m thick above the former riverbed and about 20 km extending upstream from the Dam site occurs above Gezhou Dam. The backwater can reach 150 km due to elevated water level to 27 m by the damming at the end of展开更多
较为准确地预估三峡库区9月份来水流量,对于安全而有效地完成三峡水库蓄水任务具有重要的实用意义。通过相关分析,发现三峡库区9月的来水流量与长江流域(Yangtze River Valley,YRV)上游大多数气象站点的8月降水量有显著的正相关,据此定...较为准确地预估三峡库区9月份来水流量,对于安全而有效地完成三峡水库蓄水任务具有重要的实用意义。通过相关分析,发现三峡库区9月的来水流量与长江流域(Yangtze River Valley,YRV)上游大多数气象站点的8月降水量有显著的正相关,据此定义了影响三峡库区来水流量的长江流域上游前期降水关键区。计算关键区内各气象站点8月降水量的算术平均值,并对比其与三峡库区9月三峡库区来水流量的年际变化,发现两者的变化较为一致,同样具有显著的正相关关系,因此长江流域上游前期降水关键区的8月降水量可以作为预估9月三峡库区来水流量的一个重要因子,这可以为三峡水库蓄水计划的制定提供一定的参考依据。还分析了相应的大气环流背景,发现三峡库区来水流量的多少与大气环流的变化具有密切的联系,即三峡库区来水流量偏少的年份,天气形势及水汽输送等因素都不利于降水过程的发生,进而可能导致三峡库区后期的来水流量偏少;相反地,在三峡库区来水流量高值年,天气形势和水汽输送都有利于降水过程的发生,使后期三峡库区来水流量偏多。展开更多
基金supported by tbe National Natural Science Foundation of China(Grant No.40341009)APN/START(Grant No.2004-06-CMY)the Global Environment Research Fund of the Ministry of the Environment of Japan
文摘In late May and early June, 2002, a field inves- tigation was conducted along the Three-Gorges valley of the upper Yangtze catchment by ADP (Acoustic Doppler Profile SONTEK-500). Data obtained when surveying were accom- panied with discharge of <15000 m3/s in the valley and char- acterize the unique river-flow velocity profile and riverbed morphology. Taking into consideration the relationship be- tween the average flow velocity and fluvial variables, four distinct river sections can be highlighted, i.e. Chongqing- Wanxian, Wanxian-Fengjie, Fengjie-Zigui and Gezhou res- ervoir area (upstream to downstream). The average flow velocity is in-phase with river width from Chongqing to Wanxian. High-flow velocity ranging from 3.0 to 4.0 m/s is recorded at many sites, where the wider river channel (>1000 m) and shallower water depth (<20 m) occur and large-size gravel shoals prevail. Alternated low-flow velocity (<1.5 m/s) appears at those river sections with deep water (>50 m) and U-shaped river-channel morphology. Mapping the river cross-section area at those sites can determine that smaller cross-section area accelerates the flow velocity. From Wanxian to Fengjie, the average flow velocity ranging from 3.0 to 4.5 m/s is in-phase with the water depth. The high-flow velocity is associated with narrower river-channel, where V-shaped gorges valley occurs with small cross-section area. Further downstream from Fengjie to Zigui, the low flow ve- locity is linked to deep river channel characterized by W-shaped valley morphology of large cross-section area, in general. The average flow velocity is 2.5―3.5 m/s, and maxi- mum can reach 6.0 m/s near Wu-Gorge. Our survey had also detected a slow-flow velocity (mostly <1.0 m/s) in the river channel of about 100 km long in the Gezhou reservoir downstream. Heavy siltation to 20 m thick above the former riverbed and about 20 km extending upstream from the Dam site occurs above Gezhou Dam. The backwater can reach 150 km due to elevated water level to 27 m by the damming at the end of
文摘较为准确地预估三峡库区9月份来水流量,对于安全而有效地完成三峡水库蓄水任务具有重要的实用意义。通过相关分析,发现三峡库区9月的来水流量与长江流域(Yangtze River Valley,YRV)上游大多数气象站点的8月降水量有显著的正相关,据此定义了影响三峡库区来水流量的长江流域上游前期降水关键区。计算关键区内各气象站点8月降水量的算术平均值,并对比其与三峡库区9月三峡库区来水流量的年际变化,发现两者的变化较为一致,同样具有显著的正相关关系,因此长江流域上游前期降水关键区的8月降水量可以作为预估9月三峡库区来水流量的一个重要因子,这可以为三峡水库蓄水计划的制定提供一定的参考依据。还分析了相应的大气环流背景,发现三峡库区来水流量的多少与大气环流的变化具有密切的联系,即三峡库区来水流量偏少的年份,天气形势及水汽输送等因素都不利于降水过程的发生,进而可能导致三峡库区后期的来水流量偏少;相反地,在三峡库区来水流量高值年,天气形势和水汽输送都有利于降水过程的发生,使后期三峡库区来水流量偏多。
