Many large and small rivers in Hainan Island flow into the sea from the central mountainous or hilly areas, forming a radial island water system. There are only 154 rivers flowing into the sea on the island, and the average catchment area of each river is only 220 square kilometers. Among them, there are 39 watersheds with an area exceeding 100 square kilometers, accounting for 84.4% of the total island area; There are 1 15 rivers with rainfall collection area less than 100 square kilometers, accounting for only 15.6% of the whole island area.
The island's average annual runoff depth is 909 mm, with an average annual runoff of 30.8 billion cubic meters. Groundwater reserves are 7.9 billion cubic meters, of which 5.35 billion cubic meters are river runoff (that is, double counting), so the average total water resources for many years is 33.35 billion cubic meters. The average annual rainfall in Hainan Island is 1.758 mm, with a rainfall of 59.63 billion cubic meters.
In 20 18, the proportion of days with excellent ambient air quality in Hainan exceeded 98%, and the excellent rates of seawater quality in major rivers, lakes and reservoirs and coastal waters were 94.4% and 96.6% respectively, and the forest coverage rate was stable at 62. 1%.
Extended data:
Seen from the plane, Hainan Island looks like an oval Sydney, located in the blue sea. The major axis of Hainan Island is northeast-southwest, about 300 kilometers long, and the minor axis is northwest-southeast, about 180 kilometers long, covering an area of about 34,000 square kilometers. It is the second largest island in China after Taiwan Province Province.
Hainan Island is separated from Qiongzhou Strait in the north and faces Leizhou Peninsula. Qiongzhou Strait, about 30 kilometers wide, is a maritime "corridor" between Hainan Island and Chinese mainland, and also a shipping channel between Beibu Gulf and South China Sea. Due to its proximity to the mainland, majestic mountains and towering Wuzhishan, Hainan Island can be seen faintly from the southern coast of Leizhou Peninsula when the weather is clear and there are no clouds in Wan Li. Is there one in the northwest of Hainan Island? Fushuizhou Island, also known as Nightingale Island.
Hainan Island is a coastal island with a short history but beautiful scenery, and it is the second largest island in China. In geological period, Hainan Island was initially connected with Cathaysian mainland, and then it was an island formed by fault depression.
Baidu Encyclopedia-Hainan Island