| Adopt remote sensing technology can obtain information about suspended sediment concentration of large water areas in a long periods and effectively monitor suspended sediment distribution and its dynamic change, so it has important significance for analyzing the characteristics of sediment movement. Taking Hengmen Eastern Channel as study area, remote sensing images of different periods and hydrological data of the Pearl River estuary are collected. A MIKE 21 FM hydrodynamic model is set up and the flow field images based on remote sensing technology are made, to confirm the dynamic characteristics of Hengmen Eastern Channel. The relative suspended sediment concentration's remote sensing model is established to study suspended sediment concentration variations in different periods or regions and the suspended sediment distribution in some extreme weather of Hengmen Eastern Channel by analyzing the ratio of suspended sediment concentration. The conclusions educed by this paper are as follows:1.There is a dynamic-equilibrium boundary in the LingDingyang. Between the boundary, the western part is mainly with run-off dynamic and the eastern part is mainly with tidal dynamic. Divided by the turning point in Qi'ao Island, on the north of the turning point, run-off dynamic is in charge, and tidal dynamic is relatively stronger in the dry season; south of the turning point, channel is controlled by tidal dynamic. On the West side of the Hengmen Eastern Channel, Ermao Shoal and Qi'ao Island are effected by tidal and run-off dynamic. On the east side, specially the Jinkou Shoal is obviously effected by tidal dynamic. Runoff from eastern flow of the Hengmen Eastern Channel and Jiaomen is intersected with tide.2.Remote sensing images of different periods and the empirical-quantitative remote sensing model for suspended sediment are combined to set up the relative suspended sediment concentration's remote sensing model of the Pearl River estuary. Verify the model to prove the simulation can reflect the uspended sediment distribution in the studied area. The model applies to the remote-sensing images of different years in the Pearl River estuary.3. There is a obvious concentration's boundary in the Pearl River's estuary where the Hengmen Eastern Channel lies, and is well accordance with the dynamic equilibrium boundary. Suspended sediment's concentration is demarcated by the boundary, showing the phenomenon that the concentration is high in the west and low in the east. Distribution of high concentration suspended sediment is focused on the shoal on both sides of the Hengmen Eastern Channel, including Ermao shoal and Jinkou Shoal. The Hengmen Eastern Channel has an obvious suspended sediment transport corridor and its beam effect is strong. From east to west, the suspended sediment's concentration is lower than the shoals in two sides, and suspended sediment's concentration of Ermao Shoal is higher than Jinkou Shoal. From south to north, suspended sediment's concentration is higher on the north of the turning point in Qi'ao Island than on the south.The area of high suspended sediment's concentration on the Ermao Shoal is mainly due to shoal's sediment interception and joint between run-off and tidal current, sediment raised induced by tidal currents will increase concentration. Around the Qi'ao Island, controlled by topography, a slow flow area is formed where suspended sediment remains. Runoff is intersected with tide during spring tides, increase the suspended sediment's concentration. On the Jinkou Shoal, shoal's sediment interception is weak, a great deal of sediment is composed with sediment interception and sediment-carrying capacity of tidal currents.4. In the flood season, Run-off dynamic is in charge from Lanshan segment to Ermao segment on Hengmen Eastern Channel, The stronger the tidal dynamic is, the more sediment is composed with sediment interception and sediment-carrying capacity of tidal currents, and the higher the concentration is. On the south of the Qi'ao Island turning point, Hengmen Eastern Channel is controlled by tidal dynamic, sediment transport capacity of flood tide shows significant influence.During the the edd of spring tides, the concentration of suspended sediment is the highest.In the dry season, Run-off dynamic is in charge on Lanshan segment on Hengmen Eastern Channel. From Ermao segment on Hengmen Eastern Channel to the turning point of Qi'ao Island, the tidal dynamic is in charge, sediment is mainly composed with sediment interception and sediment-carrying capacity of tidal currents. On the south of the Qi'ao Island turning point, Hengmen Eastern Channel is controlled by tidal dynamic.During the the rapid flood of spring tides, the concentration of suspended sediment is the highest.In a year time, the concentration of suspended sediment is higher in the flood season than the dry season.5. During weather extremes, level 4-5 wind or 7 level gust, can wave and raise sediment. Except the Lanshan segment, suspended sediment's concentration of the Hengmen Eastern Channel increases obviously. Wind can raise more sediment in the dry season than in the flood season. The longer the wind lasts, the more sediment suspends.After Typhoons passed by, run-off increases, in this case, suspended sediment's concentration of Lanshan segment raises to Level 3. Typhoons promote the sediment interception and sediment-carrying capacity of tidal currents, suspended sediment's concentration of flood tides and Hengmen Eastern Channel increases substantially.In rainstorm weather, run-off carries more suspended sediment. From Lanshan segment to Qi'ao segment on Hengmen Eastern Channel, suspended sediment's concentration reaches the peak, but it is limited in the area on the north of the Qi'ao Island. |
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