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Poster Session Q
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Remote Sensing study for environmental and engineering geology in Lianyungang
The tendency of sand and mud movement and its effect on the harbor
In order to enlarge the handling capacity of Lianyungang harbour, it is suggested that a dam connecting inland and East-West Liandao island be built.
The length of the dam would be 67 km. The project is going to be carried out (Fig 4).
Based on dynamic analysis and researches so aerial photos of differential periods of times in Lainyungang,
the general deposition erosion tendency in
past 30 years can be stated as follows:
The west of Haizhou Bay has been under deposition for a long period of. The east has been under erosion since the Yellow river changed its channel and flowed into the sea at Shantong in 1855. The middle part of the harbour belongs to steady coast of rock. According to the real hydraulic data, the harbour has been under deposition-erosion balance for a long time. Maintaining of the state is related closely to not only back and forth currents formed by the flowing of two coastal currents form S to N alternately in two sides of the harbour in the bay, but also the 'wave-shaped back-forth current produced by tide. The two coastal currents can be seen on TM2 image flowing through the bay, carrying sand and mud (Photo 2 Landsat 5 TM2). The problems are: Nowadays the currents can flow through the bay. As the dam constructed, the bay will come semiislandshaped' cape, the Photo 2 Landsat 2 TM2 Two coastal currents flowing through from S to N alternatively harbour 'bag-shaped' cape bay. Curvature of Haizhou Bay will beenlarged in the west. Simultaneougly, the original water-power condition will not exist. North coastal current will bend to flow outside the island. The direct effects brought about on the harbour is stated as follows.
- Sand and mud brought by coastal current may deposit at three deifferent paces. Haizhou Bay, East Liandao island and harbour.
- The deposition may be increased in Haizhou Bay. It will endanger the function of the outside of the dam.
- Sand mouth may be formed in the east of Laindao island, which may bring disadvantage to the safty of the main channel.
- After detouring to outer part of Liandao island, the coastal current, flowing from N To S, forms a circling current in the east. The coast current flowing from S to N flows directly through relatively narrow cape-shaped 'bag' and into the wide harbour, which will increase the deposition in the harbour and reduce the function of the harbour.
- After the dam is built, the harbour will be in 'semi-sealed' state' which will increase the contamination in the harbour.
After all, with the construction of the sea-cross dam carried out, more attention must be paid to two coastal currents as well as the effect brought by the change of hydraulic condition. Whether semisealed or open dam is built, further consideration must be taken. It is believed that the open dam may preserve the original waterpower condition, natural movement of back and forth currents and originally good hydraulic engineering geology environment.
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