摘要
It is very important to study the nontidal region, because characteristics in this area are very useful to us, for example, the tide range is small and the tide current is very strong. Suspended load isn’t easy to deposite and the bed load is easy to move along the sea bed. Since 1936 many scientists think that there is a nontidal point M2 in the old eatuary (38°-38°10′N, 119°-119°20′E), and have determined the location of nontidal point. According to our observation, it isn’t a nontidal point but a nontidal line. This line is located near the section B.On the 15th day of lunar calendar this line is just located at section B, and in other days this line moves toward section A, but does’nt arrive in seetion A. The tide data that,have been observed on coast tide stations give eloquent proof of fact of nontidal line. In this region of near nontidal line the current speed is more than 90cm/sec., and the maximum is 120cm/sec. The minimum of tide range is about 30cm and the maximum is about 100cm. During the flood tide the current direction is south-east, and north-weat during the ebb tide. The residual current speed on section B is about 0.2 knot,and flow into north-west.
It is very important to study the nontidal region, because characteristics in this area are very useful to us, for example, the tide range is small and the tide current is very strong. Suspended load isn't easy to deposite and the bed load is easy to move along the sea bed.Since 1936 many scientists think that there is a nontidal point M2 in the old eatuary (38°-38°10'N, 119°-119°20'E), and have determined the location of nontidal point. According to our observation, it isn't a nontidal point but a nontidal line. This line is located near the section B. On the 15th day of lunar calendar this line is just located at section B, and in other days this line moves toward section A, but does'nt arrive in section A. The tide data that have been observed on coast tide stations give eloquent proof of fact of nontidal line. In this region of near nontidal line the current speed is more than 10 cm/see., :and the maximum is 120 cm/see The minimum of tide range is about HO cm and the maximum is about 100 cm. During the flood tide the current direction is south-east, and north-weat during the ebb tide. The residual current speed on section B is about 0.2 knot,and flow into north-west.
