The Experimental Study And Numerical Simulation Of The Salt-Water Intrusion In Estuary

Due to upstream freshwater mix with sea saltwater each other, the waters nearby estuaries form the salt-water stratification, and shows various degrees of stratification under the under the influence of the density difference. Sometimes, interfaces appear clearly between the salt and water layer, and the saltwater insert the bottom of fresh water in the form of " wedge ", and move up and down with the tides along the river channel.The salt-water intrusion has many negative effects. Fistly, it can affect the hydrodynamic characteristics,sediment transport and the diffusion process of the waste heat and sewages. Secondly, It has seriously affect the domestic water,industrial and agricultural water and the aquaculture about the freshwater Biology. So it has a certain academic value to research the salt-water intrusion and its movement discipline.In this paper, based on the physical model testing, saltwater wedge motion discipline in fresh and salt water mixing area are considered, the relationship between the salt-water stratified intensity and parameters such as the runoff tidal level,tide range and salinity are analyzed, the variation of main related parameters are showed, the length of salinity intrusion are estimated, the numerical simulation combined with ECOMSED mathematical model to the salt-water intrusion are conducted. Main contents include:(1) Based on the extensive literature, a more comprehensive understanding about the research methods,research status and influence factors of salt water intrusion.(2) Doing a lot of test prophase work, for example, the planning and design on the physical model test, the layout of salinity point, and the installation and debugging on the equipment, and the calibration and correction of salinity probe test prophase work. Further exploration are conducted through the physical model test in order to analyze the effect on the salt water invasion of factors.(3) Different upstream freshwater runoff (0.5l/s,1l/s,2l/s),water depth (10cm,13cm,16cm),tide range (2.7cm,3.6cm,4.5cm) and salinity (8‰,12%o,19.2%o) are combined, and the typical cases are selected to do physical model test. By analyzing the experimental data, the relationship between the length of salinity intrusion and these parameters can be obtained.(4)Using the ECOMSED model, three-dimensional hydrodynamic numerical model in estuaries is established, and the grid dividing,the setting of initial conditions and boundary conditions,the selection of calculating parameters and the program debugging has been done. The mathematical model on the salt water intrusion has been tested by selecting the three experiment conditions with 11/s (upstream runoff),13cm (water depth),12%o (salinity), 2.7cm or 3.6cm or 4.5cm (tide range), altogether three groups.(5) The results of numerical count are compared with the data from the physical model to test and verify the ECOMSED mathematical model in the simulation of the salt-water intrusion in estuary.