Study On The Periodical Changes Of Mud Fluid In The Northern Channel Changjiang Estuary

The periodical changes of mud fluid has great significance for the understanding of mud fluid in the northern channel changjiang estuary. Furthermore, the point analysed has significance for the growth condition, evolutive rule of mud fluid and effect to run of the northern channel sea-route.Mud fluid of the northern channel Changjiang estuary are studied by using Empirical eigenfunction(EOF) and Spectrum analysis, which reduces space-time dimension and analysed the max contribution of time eigenfunction. It has been proved that the reality of the analysis result and put the recurrence period of the mud fluid's thickness variety forward in the northern channel skillfully.Based on the thickness data of mud fluid from 2000.7 to 2000.11, it is designed two schemes, in the entire sea-route from during 2000.7 to 2000.11, and in 258# during spring to neap in September. With the first five periods for the first scheme and the first four periods for the second scheme calculated by EOF and Spectrum analyse method, it can analyse the corresponding infection factors of mud fluid by integrating hydrologic matters between 1999 and 2000, observations of water-temperature , tide, salinity, velocity and direction of flow and typhoon. In the first scheme, fine sediment variable supply accounts for 56.29%-contribution Rate of the infection factor, while water temperature change of monthly accounts for 15.28%, salinity change of monthly for 10.99%, the other dynamic factors for 15%;In the second scheme, flood and ebb tide's periodical change accounts for 86.64%, 77.55% and 51.97%, while tidal current acceleration accounts for 2.8%,7.59%, and 16.51% both from spring to neap.According to the result of the model above, the form and scattering mechanism of the mud fluid are studied by integrating the fine sediment variable concentration, fine sediment apply and the mud fluid variable size. The results show that comparing with dynamic and flocculation actions, the fine sediment variable supply have a dominant effect on the mud fluid forming course;the flood and ebb tide's periodical change have a dominant effect on the mud fluid daily change. Therefore , with the dynamic action becoming lower from spring to neap, the effect of flood and ebb tide's periodical change gradually weakened while the effect of tidal current accelerationgradually strengthened.