The influence of density,foliage and stem flexibility on the roughness coefficients under unsubmerged conditions,such as Manning＇s n,is investigated experimentally.An instrumentation system has been developed for mea...The influence of density,foliage and stem flexibility on the roughness coefficients under unsubmerged conditions,such as Manning＇s n,is investigated experimentally.An instrumentation system has been developed for measuring the flow rate ranging from 0.1 to 0.3 L/s under the condition of different artificial foliated reeds.Based on the experimental results,the influence on the relationship between n with different density,foliage,flexibility and flow depth is discussed.It is found that the foliage and the density are the important factors affecting Manning＇s n.At a range of relatively low velocity and relatively large bending stiffness of stem,Manning＇s n is not influenced significanthy by the flexibility of stem.展开更多
The rotary ring flume is used to study the silty sand movement in a periodic alternating current.Characteristics of sediment movement of different coasts in the tidal current are summarized.More detailed analysis of e...The rotary ring flume is used to study the silty sand movement in a periodic alternating current.Characteristics of sediment movement of different coasts in the tidal current are summarized.More detailed analysis of erosion-sedimentation function in a numerical simulation is made.The equilibrium sediment concentration is advanced.Based on the equilibrium sediment concentration,the seabed erosion-sedimentation index is derived and the seabed erosion-sedimentation calculation is analyzed.The seabed erosion-sedimentation index is used to calculate the seabed evolution of Yangshan sea area and a good agreement with field measurements is obtained.展开更多
Temporal and spatial variations of the back-silting strength in the north passage channel of Changjiang Estuary are investigated using the empirical orthogonal function （EOF） method, with the aim to determine the im...Temporal and spatial variations of the back-silting strength in the north passage channel of Changjiang Estuary are investigated using the empirical orthogonal function （EOF） method, with the aim to determine the imposed processes and time-scales. Data on back-silting quantity in every dredging unit of the channel have been collected since March 2000,predominantly once 15 d. The EOF analysis of the back-silting strength reveals two significant modes, which totally explain 58.33% of the overall variance, and the corresponding processes and time-scales. The first EOF mode shows a clear annual cycle which is determined by the riverine water and sediment discharge from the upstream. The second EOF mode reveals a close relation between the back-silting strength and project activities. Because the processes are greatly interrelated in this study case, the other EOF modes accounting for 41.67% of the total variance do not show clear processes and time-scales.展开更多
基金The Public Science and Technology Research Funds Projects of Ocean under contract Nos 200905001 and 201005019UNESCO-IHE Partnership Research Fund (UPaRF) under contract No.60038881the National Natural Science Foundation of China under contract No.50939003
文摘The influence of density,foliage and stem flexibility on the roughness coefficients under unsubmerged conditions,such as Manning＇s n,is investigated experimentally.An instrumentation system has been developed for measuring the flow rate ranging from 0.1 to 0.3 L/s under the condition of different artificial foliated reeds.Based on the experimental results,the influence on the relationship between n with different density,foliage,flexibility and flow depth is discussed.It is found that the foliage and the density are the important factors affecting Manning＇s n.At a range of relatively low velocity and relatively large bending stiffness of stem,Manning＇s n is not influenced significanthy by the flexibility of stem.
基金The Public Science and Technology Research Funds Projects of Ocean under contract Nos 200905001 and 201005019UNESCO-IHE Partnership Research Fund (UPaRF) under contract No.60038881the National Natural Science Foundation of China under contract No.50939003
文摘The rotary ring flume is used to study the silty sand movement in a periodic alternating current.Characteristics of sediment movement of different coasts in the tidal current are summarized.More detailed analysis of erosion-sedimentation function in a numerical simulation is made.The equilibrium sediment concentration is advanced.Based on the equilibrium sediment concentration,the seabed erosion-sedimentation index is derived and the seabed erosion-sedimentation calculation is analyzed.The seabed erosion-sedimentation index is used to calculate the seabed evolution of Yangshan sea area and a good agreement with field measurements is obtained.
文摘Temporal and spatial variations of the back-silting strength in the north passage channel of Changjiang Estuary are investigated using the empirical orthogonal function （EOF） method, with the aim to determine the imposed processes and time-scales. Data on back-silting quantity in every dredging unit of the channel have been collected since March 2000,predominantly once 15 d. The EOF analysis of the back-silting strength reveals two significant modes, which totally explain 58.33% of the overall variance, and the corresponding processes and time-scales. The first EOF mode shows a clear annual cycle which is determined by the riverine water and sediment discharge from the upstream. The second EOF mode reveals a close relation between the back-silting strength and project activities. Because the processes are greatly interrelated in this study case, the other EOF modes accounting for 41.67% of the total variance do not show clear processes and time-scales.
