Various orders of condensed sections are recognized in the Cambrian of North China Carbonate Platform. Study of comparative sedimentology proves that CS4-CS5 in the Changshanian age is the maximum sea flooding sedimen...Various orders of condensed sections are recognized in the Cambrian of North China Carbonate Platform. Study of comparative sedimentology proves that CS4-CS5 in the Changshanian age is the maximum sea flooding sediments in the Cambrian, regardless of the distribution, thickness, internal structure of the condensed section series and K2O abundance. It is a two-layered composite condensed section series, characterized by the enrichment of such elements as K, P, Mn, Ti, Co, V, Cr, Cu, Zr, Ni, Li, Th, La, Ce, Nd, Dy, Y, Sc and Be. The Changshanian maximum flooding event can be correlated on a global scale, and the corresponding sedimentary records are discovered in 26 intercontinental sections in N. Europe, N. America, and Tarim and the Yangtze Platform of China. Through detailed sedimentological research, meter-scale cycle analysis and Fischer plots, it is concluded that the Changshanian maximum flooding was a composite effect of the second-order eustacy superimposed by the third-and fourth-order eustacy, which lasted for 1.2-3 Ma. An intercontinental model of the Changshanian maximum flooding is proposed at the end of this paper.展开更多
The maximum flooding event and condensed section are one hot subject in modern se-quence stratigraphy and cyclic stratigraphy. Condensed section (CS)is defined as very thinabyssal or bathyal facies stratigraphic unit,...The maximum flooding event and condensed section are one hot subject in modern se-quence stratigraphy and cyclic stratigraphy. Condensed section (CS)is defined as very thinabyssal or bathyal facies stratigraphic unit, with extremely low rate of sedimentation andbroad extension at the maximum flooding age. It is an important indicator fordetermination of the maximum flooding event. In recent years, the coneeption ofcondensed section has been opened up in not only its formation depth but also thedistributive scope after the discovery of glauconitic CS in North China Platform inCambrian by the aothors, and the condensed section is defined as the low-rate marinestratigraphic unit formed at the maximum flooding stage. It is the key to age determinationand correlation of craton basinal sequence.展开更多
A strong rainfall during June 8-13,2010 in Zunyi City is comprehensively analyzed by several diagnosis methods,including space location,maximum value,history comparison,maximum value assumption and disaster influence ...A strong rainfall during June 8-13,2010 in Zunyi City is comprehensively analyzed by several diagnosis methods,including space location,maximum value,history comparison,maximum value assumption and disaster influence analysis.Results show that this time the successive heavy precipitation fall in the northeastern area of Zunyi City,which are Zheng’an,Daozheng and Wuchuan etc..There are in total of 4 times of heavy rainstorms,8 times of rainstorms and 8 times of heavy rains in 14 meteorological observatories of the entire city.In the whole 215 towns,the daily precipitation in 162 stations reaches rainstorm scale,of which 45 stations reaches heavy rainstorm scale.The 24 hours rainfall of the heavy rain in Wuchuan Maotian town reaches 288.6 mm and the maximum rainfall intensity is 90.2 mm.The total precipitation from 22:00 on 7th to 05:00 on 10th in Fenshui,Wuchuan reaches 423.0 mm.The 1 h maximum precipitation,daily maximum precipitation and the maximum precipitation in any 3 days all surpasses the rainstorm which occurs once in a hundred years.The heavy precipitation results in large range of water-logging and flooding;the water level of several rivers passes the dangerous or warning line.The damages and impacts of the disaster are also put forward in this paper.展开更多
The analysis of the risk of flooding upstream from the Imboulou hydroelectric dam on the Léfini River in the Republic of Congo-Brazzaville, focused on the evolution of annual rainfall and flow in the study area d...The analysis of the risk of flooding upstream from the Imboulou hydroelectric dam on the Léfini River in the Republic of Congo-Brazzaville, focused on the evolution of annual rainfall and flow in the study area during the period from 1970 to 2020 before and after the building of the dam in 2005, by applying statistical methods. These methods were used to analyse the spatial and temporal evolution of rainfall and flow at the unique hydrometric station located at the RN2 (National Road N°2) bridge in the village of Mbouambé in the Pool region. This work has shown that rainfall is not the cause of flooding in the Léfini catchment area. The monthly flow coefficient (MFC) showed exceptional flooding from November and December onwards after the dam was built, resulting in a variability of flows, with periods of high and low water. In addition, the annual average flow (AAF) and the maximum average flow (MAF) increased after the dam was built. Maximum average flows (MAF) were higher than annual average flows (AAF) throughout the period of study (1970-2020). The annual and monthly rainfall-runoff relationship showed changes after the dam was built, particularly from 2009 and during the months of November and December. .展开更多
文摘Various orders of condensed sections are recognized in the Cambrian of North China Carbonate Platform. Study of comparative sedimentology proves that CS4-CS5 in the Changshanian age is the maximum sea flooding sediments in the Cambrian, regardless of the distribution, thickness, internal structure of the condensed section series and K2O abundance. It is a two-layered composite condensed section series, characterized by the enrichment of such elements as K, P, Mn, Ti, Co, V, Cr, Cu, Zr, Ni, Li, Th, La, Ce, Nd, Dy, Y, Sc and Be. The Changshanian maximum flooding event can be correlated on a global scale, and the corresponding sedimentary records are discovered in 26 intercontinental sections in N. Europe, N. America, and Tarim and the Yangtze Platform of China. Through detailed sedimentological research, meter-scale cycle analysis and Fischer plots, it is concluded that the Changshanian maximum flooding was a composite effect of the second-order eustacy superimposed by the third-and fourth-order eustacy, which lasted for 1.2-3 Ma. An intercontinental model of the Changshanian maximum flooding is proposed at the end of this paper.
基金Subject supported by the National Natural Science Foundation of China, Royal Society of UK and China Association for Science and Technology.
文摘The maximum flooding event and condensed section are one hot subject in modern se-quence stratigraphy and cyclic stratigraphy. Condensed section (CS)is defined as very thinabyssal or bathyal facies stratigraphic unit, with extremely low rate of sedimentation andbroad extension at the maximum flooding age. It is an important indicator fordetermination of the maximum flooding event. In recent years, the coneeption ofcondensed section has been opened up in not only its formation depth but also thedistributive scope after the discovery of glauconitic CS in North China Platform inCambrian by the aothors, and the condensed section is defined as the low-rate marinestratigraphic unit formed at the maximum flooding stage. It is the key to age determinationand correlation of craton basinal sequence.
基金Supported by Zunyi City Science and Technology Program(Zunyi Science Agriculture No.200904)~~
文摘A strong rainfall during June 8-13,2010 in Zunyi City is comprehensively analyzed by several diagnosis methods,including space location,maximum value,history comparison,maximum value assumption and disaster influence analysis.Results show that this time the successive heavy precipitation fall in the northeastern area of Zunyi City,which are Zheng’an,Daozheng and Wuchuan etc..There are in total of 4 times of heavy rainstorms,8 times of rainstorms and 8 times of heavy rains in 14 meteorological observatories of the entire city.In the whole 215 towns,the daily precipitation in 162 stations reaches rainstorm scale,of which 45 stations reaches heavy rainstorm scale.The 24 hours rainfall of the heavy rain in Wuchuan Maotian town reaches 288.6 mm and the maximum rainfall intensity is 90.2 mm.The total precipitation from 22:00 on 7th to 05:00 on 10th in Fenshui,Wuchuan reaches 423.0 mm.The 1 h maximum precipitation,daily maximum precipitation and the maximum precipitation in any 3 days all surpasses the rainstorm which occurs once in a hundred years.The heavy precipitation results in large range of water-logging and flooding;the water level of several rivers passes the dangerous or warning line.The damages and impacts of the disaster are also put forward in this paper.
文摘The analysis of the risk of flooding upstream from the Imboulou hydroelectric dam on the Léfini River in the Republic of Congo-Brazzaville, focused on the evolution of annual rainfall and flow in the study area during the period from 1970 to 2020 before and after the building of the dam in 2005, by applying statistical methods. These methods were used to analyse the spatial and temporal evolution of rainfall and flow at the unique hydrometric station located at the RN2 (National Road N°2) bridge in the village of Mbouambé in the Pool region. This work has shown that rainfall is not the cause of flooding in the Léfini catchment area. The monthly flow coefficient (MFC) showed exceptional flooding from November and December onwards after the dam was built, resulting in a variability of flows, with periods of high and low water. In addition, the annual average flow (AAF) and the maximum average flow (MAF) increased after the dam was built. Maximum average flows (MAF) were higher than annual average flows (AAF) throughout the period of study (1970-2020). The annual and monthly rainfall-runoff relationship showed changes after the dam was built, particularly from 2009 and during the months of November and December. .
