Unexpectedly, there is a "desert" in the southernmost part of mainland China (including Hainan Island)!

When it comes to deserts, it is not unfamiliar to Chinese people. Deserts are also one of the main landforms in our country. There are deserts in our country like Taklimakan Desert, Badain Jaran Desert, Tengger Desert and so on. Among them, the Tanramakan Desert in the center of the Tarim Basin in Xinjiang is the second largest desert in the world by area and the largest mobile desert in the world.

These deserts mentioned above are all distributed in the northwestern inland region of our country, very far away from the ocean. But what everyone basically doesn't know is that there is also a tropical "desert" on Hainan Island in my country.

Speaking of Hainan, each of us often associates it with tropical rain forests, especially Sanya is a famous tropical rain forest tourist city in Asia. Few people associate Hainan with deserts. But today, we will take everyone to learn about a small "desert" that covers an area of ​​more than 90,000 mu in the west of Hainan Island. The location of this small desert is the Qiziwan area in the northwest of Changjiang City, Hainan Province.

This tropical coastal desert is located between the estuary of the Zhubi River and the estuary of the Changhua River in Changjiang County, Hainan Province. It covers an area of ​​more than 500,000 mu, of which more than 90,000 mu is tropical coastal desert, which is not marked on ordinary maps in my country. .

A corner of Qiziwan

Qizi Bay is located on the west coast of Hainan Island, west of Changjiang, 3 kilometers north of Changhua Town, and 55 kilometers away from Shilu Town, the county seat of Changjiang. This bay is adjacent to Changhua Ridge to the east and the sea to the west. It is about 20 kilometers long from east to west and has an S-shaped shape. The water in the bay is clear, and the sand is soft and white as silver. The coast is full of strange peaks, strange rocks and phosphates, lush forests, blooming mountain flowers, clear springs, sunshine, and spring all year round. It is a rare natural bathing place and an ideal place for light bathing and sand bathing. The rugged rocks, different colors, dense forests, green grass, clear springs singing, silver sand beaches and the blue sea surface, make people enjoy flying.

Qiziwan Tourist Resort is the 2010 tourism planning project of Summit International Planning and Design Company. On August 25, 2016, Qiziwan was included in the fifth batch of national marine parks by the State Oceanic Administration.

Sand dunes in Qiziwan

Speaking of this, some people may have some questions. Although it can be seen from the above pictures that Qiziwan seems to have sand dunes that resemble a desert, there are not many beaches in our country. So these things that look like sand dunes, are they also ordinary beaches, just with a relatively large area?

Indeed, we cannot be sure from the surface that these dunes are so-called deserts. However, wild pineapples and wild cacti grow in the Qiziwan area, which are common plants in tropical deserts. From this point, it can be reflected that the Qiziwan area of ​​Hainan does have the characteristics of a tropical desert climate.

Chess Bay Wild Pineapple

Qiziwan Wild Cactus

Having said that, I believe what everyone wants to know most now is that Hainan Island is located in a tropical monsoon and subtropical monsoon climate zone, and it has very abundant precipitation every year. The South China area in the south of the Yangtze River in China should theoretically have a subtropical high-pressure desert climate, but it is precisely because of the influence of the monsoon climate that these areas not only have no desert climate characteristics, but have become world-famous "jiangnan water towns". Then Hainan Island, which is also in the center of the monsoon climate zone, why does the Qiziwan area have the characteristics of a desert climate?

Geographically speaking, the most core factor that determines the local climate is precipitation. From the oceans, tropical rain forests, grasslands, Gobi, and deserts, precipitation decreases in sequence, and some desert areas have no precipitation throughout the year. The annual rainfall in Qizi Bay, Hainan is 700-900 mm, which is relatively small for tropical and subtropical monsoon climate regions, but it has not reached an abnormal level. However, what you may not know is that the amount of evaporation in this area is as high as 2500 mm, which is comparable to the amount of evaporation in the Sahara Desert in Africa, which is quite unusual.

So what are the factors that cause the evaporation of Hainan Qiziwan to be so large, while the precipitation is much less than that of other places?

Let's first look at the temperature map of Hainan Island. We can see that under normal circumstances, that is, when there is no strong cold wave to affect Hainan, the temperature in the northern and western regions of Hainan Island is often much higher than that in the eastern and southern regions. This is mainly because the west side of Hainan Island is close to the Indochina Peninsula, and the dry hot wind from the southwest and northwest of the Indochina Peninsula often blows to the west and north of Hainan Island. Dry hot wind, also known as "dry wind", "hot dry wind", is often called "fire south wind" or "fire wind". It is one of the agricultural catastrophic weather and agrometeorological disasters with high temperature, low humidity and certain wind.

The east and south sides of Hainan Island are often blown by the cool southeast wind from the South China Sea. This southeast wind will not only bring coolness, but also transport a large amount of water vapor to form a certain degree of precipitation. Dry and hot wind is the opposite.

Therefore, the first conclusion can be drawn, that is, the dry and hot southwest wind and the northwest dry hot wind in the Qiziwan area have caused the area to be dry with little rain and high temperature.

Hainan temperature map

Next, let's look at the terrain factors. As Qizi Bay is located almost at the westernmost point of Hainan Island, the surrounding area is high in elevation, while the beach is low in elevation. Geographically speaking, there are three main types of rainfall: topographic rain, frontal rain, and convective rain. For Hainan, there is also a special "typhoon and rain".

Qizi Bay is located on the west side of Hainan Island, and there is a tall Wuzhishan mountain range in the center of Hainan Island. If it is the water vapor transported from the South China Sea, it will often be "intercepted" by the Wuzhishan Mountains, making it impossible for the water vapor to continue westward to produce effective precipitation in Qizi Bay further west. On the contrary, after these air currents pass the top of Wuzhi Mountain and continue to the west, they will be cold and sink. These sinking air currents will not only fail to produce precipitation, but will also make the air drier and increase evaporation. And if it comes from the water vapor coming from the Beibu Gulf side, but due to the low altitude of Qiziwan Beach, the water vapor cannot form topographic rain on Qiziwan Beach.

In addition, the "Dragon Boat Water" during the Dragon Boat Festival in South China and the Meiyu in the middle and lower reaches of the Yangtze River are typical frontal rains. Frontal rain is the rain formed by the confluence of cold and warm air. Judging from the overall geographical location of our country, Qiziwan is located in the southernmost part of my country's mainland. Due to the midsummer season, when the cold air from the north reaches the south, the forces will be very weak, and Qiziwan is surrounded by mountains, so it is difficult for the cold air to penetrate here to cause frontal rain. In the middle of winter, although the cold wave can reach here, the water vapor conditions at this time are not allowed, so precipitation cannot be produced.

As mentioned earlier, if the water vapor transported from the South China Sea is often blocked by the Wuzhishan Mountains, it is impossible to continue to produce effective precipitation in the Qiziwan area on the west side. But this does not mean that there is no water vapor supply in the Qiziwan area. In the midsummer season, when the southwest monsoon develops to its heyday, the southwest monsoon will transport some water vapor from the Indian Ocean to my country. Of course, Qiziwan will also receive this water vapor from the Indian Ocean. The monsoon water vapor is very abundant, so when the warm and humid air carrying the water vapor is rising, it will gradually become cold, and when it is cold, it will sink, and during the sinking process, it will convection with the rising air , Thus forming convective rain. This kind of convection is called "thermal convection" in geography. Therefore, this kind of convective rain mainly falls in Qiziwan in summer.

In addition, as Hainan Island is surrounded by oceans on all sides, it is vulnerable to typhoons in summer. However, since the Qiziwan side is the Beibu Gulf sea area and the sea area of ​​the Beibu Gulf sea area is narrow, it is unlikely that a typhoon will form directly. Most of the typhoons that affect Hainan come westward from northern Hainan. But there are also parts that directly affect the western part of Hainan Island from south to north, such as the 2010 Typhoon "Consen". However, there are relatively few typhoons in this trend. A typhoon traveling westward from the South China Sea will also be blocked by the Wuzhishan Mountains in the middle. The Wuzhishan Mountains will greatly weaken the typhoon. Therefore, under normal circumstances, typhoons arrive after passing Wuzhishan. The precipitation in the area of ​​Qiziwan will be relatively reduced. But in any case, the typhoon rain is relatively short, usually one or two days or even a few hours.

Therefore, it can be concluded that the precipitation in Qiziwan area is mainly due to the water vapor brought by the southwest monsoon and typhoon precipitation. However, this also mainly occurred in July and August. For most of the rest of the period, Qiziwan was affected by the dry and hot air masses in the Indo-China Peninsula, blowing dry hot air from the southwest and hot air from the northwest. This can explain why the annual evaporation in the Qiziwan area of ​​Hainan is greater than the annual precipitation. This is also the second conclusion.

Summarizing the above two conclusions, we can summarize the cause of the Qizi Bay Desert in Hainan: the annual increase in Qizi Bay is higher than the rainfall, coupled with the wind erosion of the southwest dry hot wind in the rainy season and the northwest dry hot wind in the dry season for thousands of years, forming this piece of my country A unique tropical coastal desert.

However, due to tree planting and afforestation, when we travel to Qiziwan now, we may see more green trees, but some large sand dunes still exist. If you have a chance, you might as well go there and take a look~