The Xi River (; ) or Si-Kiang is the western

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

of the Pearl River in

southern China Northern China () and Southern China () are two approximate regions that display certain differences in terms of their geography, demographics, economy, and culture. Extent The Qinling–Daba Mountains serve as the transition zone between ...

. It is formed by the confluence of the Gui and Xun Rivers in Wuzhou,

Guangxi Guangxi,; officially the Guangxi Zhuang Autonomous Region, is an Autonomous regions of China, autonomous region of the China, People's Republic of China, located in South China and bordering Vietnam (Hà Giang Province, Hà Giang, Cao Bằn ...

. It originates from the eastern foot of the Maxiong Mountain in Qujing City,

Yunnan Province Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

. Then it flows east through

Guangdong ) means "wide" or "vast", and has been associated with the region since the creation of Guang Prefecture in AD 226. The name "''Guang''" ultimately came from Guangxin ( zh, labels=no, first=t, t= , s=广信), an outpost established in Han dynasty ...

, and enters the

Pearl River Delta The Pearl River Delta Metropolitan Region is the low-lying area surrounding the Pearl River estuary, where the Pearl River flows into the South China Sea. Referred to as the Guangdong–Hong Kong–Macao Greater Bay Area in official documents, ...

just east of the Lingyang Gorge in

Zhaoqing Zhaoqing ( zh, c=肇庆), alternately romanized as Shiuhing, is a prefecture-level city in Guangdong Province, China. As of the 2020 census, its population was 4,113,594, with 1,553,109 living in the built-up (or metro) area made of Duanz ...

. The main branch of the Xi River flows southeast through the delta entering the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by South China, in the west by the Indochinese Peninsula, in the east by the islands of Taiwan island, Taiwan and northwestern Philippines (mainly Luz ...

at Modao Men, just west of

Macau Macau or Macao is a special administrative regions of China, special administrative region of the People's Republic of China (PRC). With a population of about people and a land area of , it is the most List of countries and dependencies by p ...

. The major cities along the Xi include Wuzhou, Zhaoqing, and

Jiangmen Jiangmen ( zh, c=江门), postal map romanization, alternately romanization of Chinese, romanized in Cantonese as Kongmoon, is a prefecture-level city in Guangdong provinces of China, Province in southern China. It consists of three urban distri ...

. The other two main tributaries of Pearl River are the Dong River (literally, the East River) and Bei River (the Northern River). As for other functions, it plays a vital role in carbon storage and transport in Southern China. The Xi River is facing some ecological challenges such as

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

, and

pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

Xi River system

The basin of the Xi River ranges from eastern

to southern

Guangdong Province ) means "wide" or "vast", and has been associated with the region since the creation of Guang Prefecture in AD 226. The name "''Guang''" ultimately came from Guangxin ( zh, labels=no, first=t, t= , s=广信), an outpost established in Han dynasty ...

with a humid subtropical or tropical monsoon climate. The Xi River is navigable for its entire length. It is a commercial waterway of southern China, and links the

delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...

cities to the interior. Over two thousand years ago, the

Lingqu Canal The Lingqu () is a canal in Xing'an County, near Guilin, in the northwestern corner of Guangxi, China. It connects the Xiang River (which flows north into the Yangtze) with the Li River (Guangxi), Li River (which flows south into the Gui ...

was dug, connecting the Xi River basin (the Li River, which is a tributary of the

Gui River The Gui River ( zh, s=桂江, p=Guì Jiāng) is a river in the Guangxi Zhuang Autonomous Region of China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding ...

) with the

Xiang River The Xiang River is the chief river of the Lake Dongting drainage system of the middle Yangtze, the largest river in Hunan Province, China. It is the second-largest tributary (after the Min River) in terms of surface runoff, the fifth-largest ...

, which flows into the

Yangtze The Yangtze or Yangzi ( or ) is the longest river in Eurasia and the third-longest in the world. It rises at Jari Hill in the Tanggula Mountains of the Tibetan Plateau and flows including Dam Qu River the longest source of the Yangtze, i ...

, thus providing a continuous waterway from the

to the Yangtze Valley. The Xi River is rich in water conservancy and water resources, providing significant contributions to agricultural

irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...

, river transportation, and power generation in coastal areas. The Xi River is the largest of the Pearl's tributaries. Its volume of flow is second in China only to that of the

Yangtze River The Yangtze or Yangzi ( or ) is the longest river in Eurasia and the third-longest in the world. It rises at Jari Hill in the Tanggula Mountains of the Tibetan Plateau and flows including Dam Qu River the longest source of the Yangtze, i ...

, and it supplies water to many places in Guangxi, Guangdong and Macau. The greater Xi River is also one of China's longest. Existing in many segments it extends for : *Nanpan River: *Hongshui River: *Qian River: *Xun River: *Xi River (including main branch to the sea):

Major cities along the river

* Wuzhou *

Foshan Foshan (, ; Chinese: 佛山) is a prefecture-level city in central Guangdong Province, China. The entire prefecture covers and had a population of 9,498,863 as of the 2020 census. The city is part of the western side of the Pearl River Delta m ...

( Gaoming District) * Heshan *

Zhongshan Zhongshan ( zh, c=中山 ), alternately romanized via Cantonese as Chungshan, is a prefecture-level city in the south of the Pearl River Delta in Guangdong province, China. As of the 2020 census, the whole city with 4,418,060 inhabitants is n ...

Zhuhai Zhuhai; Yale romanization of Cantonese, Yale: ''Jyūhói''; Chinese postal romanization, also known as Chuhai is a prefecture-level city located on the west bank of the Pearl River (China), Pearl River estuary on the central coast of southern ...

River Ecology

Rivers are a significant storage and transport system for both organic and inorganic carbon. The Xi River is an important source of atmospheric

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

in Southern China, with carbon inputs coming mainly from the river's headwater Nanpan and Beipan rivers. In the Beipan River, carbon inputs come from the oxidation of organic carbon and the coal industry along the river. In the Nanpan River, carbon inputs come mainly from soil and organic detritus.

Environmental Issues

Drought

The Xi River basin has historically experienced droughts, which are worsening due to

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

and rapid

urbanization Urbanization (or urbanisation in British English) is the population shift from Rural area, rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. ...

along with many parts of the river. This increase in population is straining water resources. The climate of the watershed is

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

to tropical monsoon, with 80% of

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

falling between April and September. This extreme variation in yearly precipitation patterns exacerbates drought issues. Climate change is predicted to cause a significant decrease in average, highest, and lowest river flows, with average flow droppings anywhere from 4 to 49%. Increasing frequency and severity lead the meteorological and hydrological droughts.

Invasive species

Invasive or non-native species are an issue in rivers in southern China, including the Xi River. Southern China rears the majority of non-native species in

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

. These species are mainly introduced from aquaculture, and may predate or outcompete

native species In biogeography, a native species is indigenous to a given region or ecosystem if its presence in that region is the result of only local natural evolution (though often popularised as "with no human intervention") during history. The term is equi ...

. Most introduced species are

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

s, including the

Nile tilapia The Nile tilapia (''Oreochromis niloticus'') is a species of tilapia, a cichlid occurring naturally in parts of Africa (such as its namesake Nile River) and the Levant, though numerous introduced populations exist outside its natural range. T ...

, the most common non-native species in southern China rivers.

Pollution

Many commercial fish species in the Xi River and the encompassing Pearl River watershed have been contaminated with significant amounts of

Bisphenol A Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on a ...

, common in plastics manufacturing. Bisphenol A is a chemical that can be harmful to the

endocrine system The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant Organ (biology), organs. In vertebrat ...

of fish and humans.

Protection

In order to protect the Xi River, the

Guangxi Zhuang Autonomous Region Guangxi,; officially the Guangxi Zhuang Autonomous Region, is an autonomous region of the People's Republic of China, located in South China and bordering Vietnam ( Hà Giang, Cao Bằng, Lạng Sơn, and Quảng Ninh Provinces) and the ...

government issued a notice prohibiting new construction projects and migration of people within the land occupied and inundated areas of the Xi River mainstream control project in Guangxi. Besides, the protection measures include: promulgated a fishing ban,

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

park protection, develop green

recycling Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials. The recyclability of a material depends on its ability to reacquire the propert ...

and low-carbon economic, the innovation of ecological and

environmental protection Environmental protection, or environment protection, refers to the taking of measures to protecting the natural environment, prevent pollution and maintain ecological balance. Action may be taken by individuals, advocacy groups and governments. ...

cooperation mechanism and Xi River Basin Nature Reserve construction management.

References

External links

WWF - Xi Jiang Rivers and Streams Ecoregion
{{Coord, 22.0602, N, 113.4792, E, source:wikidata-and-enwiki-cat-tree_type:river_region:CN-44, display=title Tributaries of the Pearl River (China) Rivers of Guangdong Rivers of Guangxi