Study On Characteristics Of Runoff And Sediment Content Evolution And Its Impact On Estuary Wetland In The Lower Yellow River

The Yellow River is the second longest river in China,feeding the children of the Chinese nation.But it is also a frequent disaster,water less sand,water and sand heterogeneous and uneven distribution of space and difficult to manage the river.Yellow River is a disaster-prone,less water and more sand,which runoff and sediment content is heterologous and uneven distribution of time and space.It is difficult to control.Yellow River Basin population is large and town-intensive.During the development and utilization of water resources,human activities such as reservoir construction,water diversion irrigation,soil and water conservation,water and sediment regulation were carried out.As the human development and utilization of the Yellow River,coupled with the natural climate and environmental changes,leading to the lower reaches of the Yellow River runoff and sediment content variation.Having a huge impact on the fragile ecological environment system of estuarine wetlands.Therefore,through the analysis of the historical and monitoring data of the main hydrological stations in the lower Yellow River,the research on the evolution of runoff and sediment content is carried out.Analysis of evolution of runoff and sediment content.Forecast the trend of downstream runoff and sediment content and its impact on estuary wetland environment.It provides the theoretical basis for the sustainable utilization of water and sand resources in the lower reaches of the Yellow River and the sustained and healthy development of regional socio-economy and ecological environment protection,has important theoretical value and practical significance.Based on the statistical analysis of the sediment concentration and runoff during the year and the inter-annual variation of the four main hydrological stations(Huayuankou station,Gaocun station,Aishan station and Lijin station)in the lower Yellow River,the runoff and sediment content of each hydrological station in the lower reaches of the Yellow River showed a decreasing trend.Runoff and sediment content during the period was seasonal and seasonal changes.Indicating that the distribution of runoff and sediment content in the lower reaches of the Yellow River during the year is relatively large and concentrated,mainly from the flood season 6 to 10 months.Using the Spearman rank correlation method and trend coefficient method to the lower reaches of the Yellow River water after sand trend analysis.The runoff and sediment content in the lower reaches of the Yellow River during the year showed a downward trend.The Mann-Kendall method was used to analyze the mutant characterization,Indicates that the lower reaches of the Yellow River water and sediment changes have respectively.Aishan station and Lijin station in the lower reaches of the Yellow River were mutated in 2005 and 1997 respectively.Using the maximum entropy spectral analysis results show that the periodic,quasi periodic sediment Huayuankou Station about 11 years,The maximum entropy spectrum analysis method was used for periodic study.The results show that the quasi-cycle of sediment concentration in the main hydrological stations are respectively about 11,8,12.5,9years.The quasi-cycle of runoff in the main hydrological stations are respectively about 8,5,3.3,3.3years.According to the theory of chaos,the water and sediment are predicted.The auto-correlation function method and saturated correlation dimension method are used to reconstruct the runoff and sediment content sequence in the lower Yellow River.The maximum Lyapunov exponent of runoff and sediment content of the main hydrological stations is calculated by using the small data method.The calculated results are all greater than zero,indicating that have chaos.The maximum Lyapunov exponent is used to predict.The relative error is within 20%,and the prediction accuracy is higher.Based on the analysis of the driving factors of the wetland eco-environmental system in the lower reaches of the Yellow River,the influence of water and sediment changes on the ecological environment of estuarine wetland in the lower reaches of the Yellow River is studied.The results show that the change of water and sediment in the lower reaches of the Yellow River is highly correlated with the eco-environmental system.The evolution trend has obvious consistency.