Qiongzhou Strait

Qiongzhou Strait

This entry is compiled and applied by "popular science China" Science Encyclopedia

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Qiongzhou Strait, located between Leizhou Peninsula and Hainan Province, belongs to China's inland sea,

It is also one of the three major Straits in China. The Strait is about 80 km long from east to west, 39.5 km wide from north to South and 19.4 km narrow from north to south, with an average width of 29.5 km. The coastline of the north and south sides of the Strait is zigzag, with headlands and bays alternating. From east to west, there are hongyajiao, paiweijiao, Yujiao and jiaoweijiao on the north bank. The headland is composed of basalt, among which hongkan Bay, Hai'an Bay and Jiaowei Bay are formed. Qiongzhou Strait is an important channel for maritime traffic between Guangdong sea area and Beibu Gulf. It connects Beibu Gulf with the middle and east of South China Sea. It is also a shortcut for maritime traffic from Guangzhou, Zhanjiang to Hainan, Guangxi and Vietnam.

On December 30, 2019, Qiongzhou Strait online ticketing system was officially launched.

geographical position

Qiongzhou Strait is located between Leizhou Peninsula in Guangdong Province and Hainan Island in Hainan Province. It is adjacent to Beibu Gulf in the West and the north of South China Sea in the East. It spans 19 ° 52 ′ ~ 20 ° 16 ′ N and 109 ° 42 ′ ~ 110 ° 41 ′ e, from Dengloujiao at the west end of Leizhou Peninsula in the north to boshujiao at the south end, and from lingaojiao to mulantou at the south end of Hainan Island. The total length of the sea is 103.5 km from east to west, the widest is 39.6 km, and the narrowest is only 19.4 km. The sea area is about 2370 square km, with an average water depth of 44 m, and the maximum depth of the sea It is 114 meters.

The division of Qiongzhou Strait is as follows: in the East, from the midpoint of the line connecting shangouhoujiao in Xuwen County of Guangdong Province and mulantou in Wenchang County of Hainan Province (110 ° 36 ′ 06 ″ e, 20 ° 17 ′ 42 ″ n), to the west, from the midpoint of the line connecting haianwan No.1 beacon and haikouwan No.1 beacon (110 ° 15 ′ 24 ″ e, 20 ° 09 ′ 24 ″ n), to the midpoint of the line connecting Dengloujiao beacon in Xuwen County and lingaojiao in Hainan Province (East) Longitude 109 ° 48 ′ 54 ″, North Latitude 20 ° 07 ′ 00 ″). The north of the line connecting the above points is under the jurisdiction of Guangdong Province, and the south is under the jurisdiction of Hainan Province.

Qiongzhou Strait is one of the three major Straits in China. It is not only the traffic throat connecting Hainan Island and the mainland, but also the best channel between Beibu Gulf and the north of South China Sea. On its south bank, there are main ports such as Puqian, Macun and Haikou.

natural environment

climate

Qiongzhou Strait has warm climate, abundant rainfall and frequent typhoons all year round. The annual average temperature in the Strait is about 24 ℃, the extreme maximum temperature is 38 ℃ ~ 40 ℃, and the minimum temperature is 28 ℃. The average annual precipitation is more than 1500 mm. The rainy season is from May to October, with thunderstorms; the dry season is from November to next April, with no snow all the year round. Southwest wind prevails in summer and northeast wind prevails in winter. The strong wind season is from November to march of the next year. The northeast wind has a long time and many times. The northeast wind is the most frequent in the whole year, accounting for about 18%. Typhoon mainly affects the Strait from May to October, with August to October being the most, with an average of 3 to 4 times per year. Typhoon is one of the main natural disasters in this area.

Geology and geomorphology

Qiongzhou Strait is located in the south of Leiqiong fault depression, and its basement is characterized by convex concave alternation. The NW and NE trending faults on both sides of the Strait extend into the Strait and intersect with the Near East trending faults. The location of Qiongzhou Strait is not the subsidence center of Leiqiong fault depression, and the terrain is very complex. Due to the influence of tidal current and the exposure of Zhanjiang coarse strata at the bottom of the gorge in the East and West, the horizontal distribution of submarine sediment types changes rapidly. In addition to modern sediments, there are also flat consolidated early sediments and weathered bedrock fragments. The basement is covered with marine Neogene (the lithology is gray green silty clay) containing poroelectrofossils and glauconite, and the thickness of the Neogene is 1500-1600 M. The upper Tertiary is covered by the lower Geng series characterized by variegated gravel, sand and clay interbedding. The top is weathered clay layer, and the lower Pleistocene is covered with 1-4 layers of volcanic rocks.

The topography of the Strait is characterized by large scale uplifts and depressions distributed intermittently, but the seabed topography is still deepened from the north and south sides to the middle of the Strait. The combined action of sand flow carrying sediment into the sea and tidal current carrying sediment in the Strait complicates the sediment movement in Qiongzhou Strait, resulting in the seasonal change of geomorphology. Especially in the south bank. In winter, the northeast wind and waves move the sediment from the shoal to the coast, silting up the bank and sand mouth, making some estuaries and tidal channels shallow or even blocked. In summer, typhoon waves erode the sandbank and sand mouth, and some sediment is washed over the top of sandbank and sand mouth by strong waves and deposited in lagoon. Sometimes, a typhoon erodes 10 meters of sand dike and silts up to 17 meters of lagoon; part of the eroded sediment is brought underwater and silts up to form a beach; sometimes, the scouring effect of typhoon surge and typhoon flood deepens and widens the estuary and tidal channel.

Wind and waves

From November to march of the next year, the wind is mostly from north to northeast, with an average wind force of 3-4, light to moderate wave; when the strong cold air affects, the weather is mostly overcast and rainy. Wind force 5.6, big wave and huge wave. From June to September, there are more southeast winds, with an average wind force of 3, ranging from small to light waves; when tropical storms hit, gusts are above 8, with a maximum of 12, and there are more huge waves and wild waves, with a wave height of more than 8 meters. 4. In May and October, the direction of wind and wave is uncertain, mostly light wave and small surge.

From January to April, it is foggy in the morning and evening or at night. The monthly average foggy days are 5-7 days, and the highest is 17 days. The continuous foggy days are generally 2-3 days, and the longest is 8 days.

hydrology

The annual average surface water temperature is 25 ℃ ~ 27 ℃, about 20 ℃ in February and about 30 ℃ in August. The surface salinity is about 30 ‰ and the transparency of sea water is about 5m.

The tide in Qiongzhou Strait belongs to irregular diurnal tide mixed tide type with small tidal range, usually about 1m. Under the influence of typhoon, the tidal range increases, and the maximum tidal range along the coast can reach 3-4m. The tidal current in the Strait belongs to regular diurnal tidal current, which is reciprocating. The current velocity in the middle part is generally 4-5 knots, and that in the East-West mouth is 3-4 knots. The surface velocity in the middle layer of the Strait is more than 6 knots, and the bottom velocity is more than 4 knots. The east current is larger than the West current, the surface current is larger than the bottom current, and the ebb current in the middle of the Strait is about one knot. There are four types of current in the South Bank of the Strait: East current of rising tide and West current of rising tide, east current of falling tide and West current of falling tide. Among them, the velocity outside Nandujiang Delta and CHENGMAIJIAO Bay is larger, about 2 knots; the velocity in Haikou Bay and Chengmai Bay is smaller, only 0.5 ~ 1.0 knots.

The current in Qiongzhou Strait is greatly affected by monsoon. In winter, the northeast wind prevails and the ocean current flows from northeast to southwest, in which the eastern surface current flows from east to west and the western surface current flows from northeast to southwest. In spring, the wind direction changes greatly, and the easterly is relatively dominant. At this time, the current mainly flows from southeast to northwest. In summer, it is mainly controlled by southeast wind and southwest wind. When the southeast wind blows, the current flows from east to northwest; when the southwest wind blows, the current flows from west to East. Most of autumn is affected by the northeast monsoon, and the ocean current flows from east to west. Therefore, except in June and July, the current in Qiongzhou Strait flows from east to West in the rest of the time. The velocity of the east current is large and that of the West current is small, but the time of the east current is short and that of the West current is long. The maximum velocity of the Strait current is 2.55 M / S ~ 3.06 M / s. the surface current along the south coast of the Strait is 0.6 m / s in the West and 0.82 M / s in the East.

The waves in Qiongzhou Strait are controlled by monsoon all the year round. From October to next June, the waves run from east to west. From July to August, the waves run from west to East. According to the wave data statistics of Baishamen, Macun and yubaojiao, the main waves are wind waves, most of which are nne-e waves, with the frequency of 77%, followed by nnw-n waves, accounting for 22%. At the depth of - 5M and - 10m offshore, the wave heights of grade 0-2 account for 79% and 69% respectively, the wave heights of grade 3 account for 17.4% and 21.4% respectively, and the wave heights of grade 4 account for 3.5% and 7.4% respectively. The average wave height is 0.5-0.6m, and the maximum wave height is 4-7m.

When Qiongzhou Strait is attacked by typhoon, strong wind sets off huge waves, and strong northwest and northeast wind drives the sea water flowing into Qiongzhou Strait from Beibu Gulf and South China Sea, which is easy to accumulate in the southern coastal bay of the Strait, resulting in a relatively large typhoon surge. The water increase in the south bank is generally 1.5 ~ 2m, and the maximum water increase is 2.5m. In 1980, the No.7 typhoon passed through Qiongzhou Strait, and the coastal water increased by 2.41 meters. Even Haikou City also gushed into the sea water. The storm surge occurred on September 27, 1948, typhoon 6311 on September 7, 1963, typhoon 8007 on July 22, 1980 and typhoon 8616 on September 5, 1986 were the four most serious storm surges in the past years, which made the maximum water increase value along the coast of Haikou City about 2.5m.

Human history

Administrative regulations

On June 8, 1965, the State Council of the people's Republic of China promulgated the "rules for the administration of non military vessels of foreign nationality passing through the Qiongzhou Strait", which mainly contains 12 articles, including the administrative organization, the scope of administration, the previous examination and approval procedures, the requirements for passing through the Strait, and the handling of violations.

Ministry of communications of the people's Republic of China

Chinese PinYin : Qiong Zhou Hai Xia