What is the population of Huangyan Island?
Huangyan Island, which belongs to Sansha City, Hainan Province, China, is the only island reef in zhongsha islands, China. Located at north latitude 15 13' 48 ",east longitude 15' 24",17 40'12 "to1/kloc-0.
Huangyan Island is surrounded by an annular reef plate between half a meter and three meters from the water surface, and the shape of the reef plate is an isosceles right triangle. Form a natural lagoon with an area of 130 square kilometers and a water depth of 10 to 20 meters.
There is a 400-meter-wide passage at the southeast end, which is connected with the open sea. Medium-sized fishing boats and small boats can enter through this passage, which is an excellent fishing ground and shelter. Huangyan Island, like Nansha Islands, is an important sea passage. Huangyan Island is rich in aquatic resources, rich in a variety of fish with high economic value.
topography
Huangyan Island is a slightly triangular atoll. The atoll is surrounded by shallow lakes, and the water color is green, which is different from the dark blue and black water outside the reef. Atolls have developed near the sea surface, and there are some high coral reefs, which are above the water surface and look like islands from a distance. There is a giant reef named "Huangyan" on the north side of the atoll.
There is also a water reef called "Nanyan" on the south reef plate. The entrance of the shallow lake is in the southeast, and there are reefs on the channel near the south and north. This intake canal is 9- 1 1 m deep and 360-400 m wide. Outside the reef is the deep water area, and the reef rises from the 4000-meter deep-sea basin to the sea like a chimney. Here, the crust is thin, with high gravity anomaly, and it is an atoll of Dayang Island.
The atoll is 15km long from east to west, 15km wide from north to south, 55km in circumference and 150km in area. The slope outside the reef often reaches 15, the slope in the south reaches 18, and the slope in the north also reaches 18, down to the seabed with a depth of 3500-4000m.
The edge of the reef plate here is where the waves break into waves, and there are more dissolved oxygen and plankton, which is beneficial to the growth and development of coral reefs. All kinds of reef-building corals have been growing to a depth of 20 meters, and there are still sporadic growth below 20 meters.
On the reef plate, the water depth is 0.5 meters and the width is 600-900 meters, and coastal corals, flat-headed corals, horned corals and helmet corals grow. Corals are huge, table-shaped and can rise above the sea. There are also reefs overturned by huge waves scattered on the reef plate, mostly in huangyan district and Nanyan area. There is karst phenomenon in the gully on the reef plate.
The lagoon (shallow lake) is 20 meters deep and there are many reefs (reefs). The date of the handover is very new. According to C 14, it is 470 90 years. Sedimentation in the lagoon is also very strong, making the shallow lake bottom flat.
There are more than 380 coral reefs above the water in huangyan district. Because the exposed water surface is dissolved by seawater and rainwater on the one hand, it causes cementation on the other hand, which is manifested as granular calcite cementation.
After dissolution, coral reefs form blocks with many pores, except for the growth skeleton pores formed by primary coral communities, which are all cavities and cracks formed by corrosion. "Huangyan" is a huge reef in dark yellow shallow water, with an area of 4 square meters exposed above the water surface, which is 1.5 meters higher than the water surface. Southern Yan has a circumference of 8m and an upper area of 3m, which is 1.8m higher than the water surface. There are dissolved stone buds and stone ditches at the top. ?
Reference to the above content: Baidu Encyclopedia-Huangyan Island