The Pearl River is a place whereXijiang River、Beijiang、DongjiangandZhujiang deltaThe complex water system formed by the confluence of various rivers generally originates from the upper source of the Xijiang River and the Yunnan Guizhou PlateauMount WumengsystemMa XiongshanIt flows through six provinces (districts) of Yunnan, Guizhou, Guangxi, Guangdong, Hunan and Jiangxi and the north of Vietnam, forming the characteristics of numerous tributaries and diverse waterways, and overflows into a network of river areas in the downstream delta, passing through theHumen、Banana Gate、Hongqimen(asphalt)Horizontal door、Knife sharpening door、Cock crowing、Tiger Leaping GateandYamenBadakoumen flows into the South China Sea.
The annual runoff of the Pearl River is more than 330 billion cubic meters, ranking second in China's river systems, only second toYangtze River, YesYellow River7 times of annual runoff,Huaihe River10 times.Total length: 2320km[1]With a drainage area of 453690 square kilometers (including 442100 square kilometers in China and 11590 square kilometers in Vietnam)[15]Is the largest river system in southern China and the third longest river in China[2]。
The abundant river water and numerous tributaries have brought superior conditions to the shipping industry of the Pearl River. The shipping value is second only to the Yangtze River, ranking second in the country.The Pearl River water system is rich in hydropower resources. The famous Tianshengqiao, Datong Gorge, Lubuge, Xinfeng River and other hydropower hubs belong to the Pearl River water system.The Pearl River Basin covers a vast area, mostly mountains and hills, accounting for 94.5% of the total area. The plains are small and scattered, accounting for only 5.5%. The relatively large area is the Pearl River Delta Plain.The Pearl River basin is rich in tourism resourcesHuangguoshu Waterfall、Guilin SceneryThey are all in the Pearl River basin.
Chinese name
Pearl River
Alias
Yuejiang
Water system
Rivers into the South China Sea
geographical position
South of China
Flow area
Yunnan, Guizhou, Guangxi, Guangdong, Hunan and Jiangxi
Origin
In Zhanyi District, Qujing City, Yunnan ProvinceMa Xiongshan[15]
Main tributaries
Yujiang River, Liujiang River, Zuojiang River, Beipanjiang River
River length
2320 km
Drainage area
453700 km²[15]
Water system composition
Xijiang River, Beijiang River, Dongjiang River and Pearl River Delta
Pearl River original referenceGuangzhouA 96 km long waterway to the sea entrance, because it flows through the famousHaizhu Island(Shi), and later became the general name of Xijiang River, Dongjiang River, Beijiang River and all rivers in the Pearl River Delta.The Pearl River is both narrow and broad.The Pearl River in a narrower sense refers to the small section of river that flows from north to south and from west to east through the urban area of Guangzhou after the Pearl River tributaries converge in the "three rivers" in the northwest of Guangzhou[3-4]。
In ancient times, the Pearl River flowed throughGuangzhouurban districtThe section of the river was originally very wide, about 2 kilometers wide.It turns out that the north bank of the Pearl River is not in Yanjiang Road, but in Zhongshan Road, while the south bank has not been changed for thousands of years.In the Pearl River, which is 2 kilometers wide, there used to be three reef islands calledHaizhu stone, seals and pumice stones.Haizhu stoneIt is a huge reef island in the old Pearl River channel, also known asHaizhu Island, near Jiangxi Road and Xindi.Haizhu Stone is called Haizhu Stone because it has been washed away by river water for a long time and is as round as a pearl.In the Song Dynasty, the stone was still located in the center of the river. Later, it was gradually connected to the land on the north bank of the Pearl River due to sediment deposition.In 1931, when the new embankment was built and Yanjiang West Road was built, the sea beads began to sink underground[3]。
Water system composition
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Water system map of the Pearl River basin
The Pearl River is a place whereXijiang River、Beijiang、DongjiangandZhujiang deltaThe composite water system formed by the confluence of various rivers generally takes the upper source of the West River as the source, so the Pearl River originates from the Yunnan Guizhou PlateauMount WumengsystemMa XiongshanIt flows through six provinces (districts) of Yunnan, Guizhou, Guangxi, Guangdong, Hunan and Jiangxi and the north of Vietnam, forming the characteristics of numerous tributaries and diverse waterways, and overflows into a network of river areas in the downstream delta, passing through theHumen、Banana Gate、Hongqimen(asphalt)Horizontal door、Knife sharpening door、Cock crowing、Tiger Leaping GateandYamenBadakoumen flows into the South China Sea.
The annual runoff of the Pearl River is more than 330 billion cubic meters, ranking second in China's river systems, only second toYangtze River, YesYellow River7 times of annual runoff,Huaihe River10 times.Total length: 2320km[1]With a drainage area of 453690 square kilometers (442100 square kilometers in China and 11590 square kilometers in Vietnam), it is the largest river system in southern China and the third longest river in China[2]。
Water system characteristics
In the Pearl River system of Guangdong,Dongjiang、Liuxi River、BeijiangIt flows from northeast to southwest,Xijiang River、Tanjiang RiverIt flows roughly from west to east, and all of them converge in the river network of the Pearl River Delta. Finally, it flows into the South China Sea from 8 Dakoumen. The whole water system is a fan like water system.
The terrain of the Pearl River Basin in Guangdong Province is inclined from north to south, and the highest peak, Shikengkong, is 1902 meters above sea level.The area of the left bank of the main stream of the Pearl River is more than 3.5 times that of the right bank.The density of river network is large, and the density of river network in delta area is more than 0.81km/square km.The bending coefficient of the main stream is 1.34, and the main stream is a flat prototype river.[5]
Xijiang River System
Xijiang River System Diagram and Wuzhou Section
trunk stream
Xijiang River, the largest mainstream of the Pearl River system, originated in Yunnan ProvinceZhanyi DistrictMa XiongshanThe northeast foot (also the source of the Pearl River).The main stream flows through Yunnan, Guizhou, Guangxi and Guangdong to GuangdongKnife grinding gate water channelEnterprise human stoneIt flows into the South China Sea with a total length of 2214km and an average gradient of 0.45 ‰.SixianjiaoThe catchment area above is about 353120 square kilometers.In GuangxiXiangzhou CountyThe upper reaches of Shilong Sanjiangkou are from Sanjiangkou toWuzhou CityMiddle reaches, from Wuzhou to Guangdong ProvinceSanshui CountySixianjiaoIs downstream,SixianjiaoTo Modaomen Qirenshi is the estuary section.
hydrology
Gaoyao Hydrological Station(The catchment area is 351535 square kilometers) The average annual runoff depth measured for many years (1956-1987) is 636.3 mm, the total runoff is 223.7 billion cubic meters, the annual sediment discharge is 71 million tons, and the erosion modulus is 202 tons/year · square kilometers.
The lower reaches of the Xijiang River in Guangdong Province covers an area of 17960 square kilometers, accounting for 16.1% of the Pearl River basin area in Guangdong Province;The river is 195km long, with an average gradient of 0.086 ‰;The river channel is about 700-2000 meters wide.There are Sanrong Gorge andAntelope gorgeIn the river bed, Sanrong Gorge is 370m wide, 55km long and 78m deep;Lingyang Gorge, also known as Zhaoqing Gorge, is 360 meters wide, 7.5 kilometers long and 83 meters deep.This area is characterized by low mountains, hills and waterlogged depressionsAntelope gorgeThe upper and lower parts basically belong to the dike area.
tributary
The tributaries along the Xijiang River with catchment area of more than 1000 square kilometers
Beijiang, originated in Jiangxi ProvinceXinfeng CountyShijie Damao Mountain, the mainstream flows through Guangdong ProvinceNanxiong County、Shixing County、Qujiang County3 counties toShaoguan City, and then turn south to flowYingde 、Qingyuan CountytoSanshui CountySixianjiao, andXijiang RiverAfter being connected, it flows into the Pearl River DeltaPanyu DistrictXiaohushan Island in Huangge Town flows out of the Pearl River estuary.The main stream is 573km long, with an average gradient of 0.7 ‰, and the catchment area is 52068km2, accounting for 10.3% of the total area of the Pearl River Basin;The part of the drainage basin enters Hunan and Jiangxi provinces.In Guangdong Province, it accounts for 92% of the Beijiang River basin, and about 38.5% of the Pearl River basin area in Guangdong Province.The average annual runoff of Beijiang River is 51 billion cubic meters, and the runoff depth is 1091.8 mm. The main stream above Shaoguan City is called Zhenjiang River (also called Zhenshui), and the downstream of Shaoguan City is called Beijiang River.The terrain is generally high in the north and low in the south. Shikengkong, the highest peak in the province, is located in some watersheds in the north, 1902 meters above sea level.
stayShaoguan CityThe upstream is above Shazhouwei, calledZhenjiang River。The river is 212km long, with an average gradient of 0.59 ‰ and a drainage area of 7554km2.There are many mountains and hills in the basin, with a small number of scattered river valleys and basins.From Wujing at the upstream to the mouth of Mojiang River, within 10 kilometers of the river bank, there are hills below 100 meters on average, and beyond 10 kilometers, there are mountains.River valleys are mostly V-shaped.The main tributaries along the river include Mojiang River, Jinjiang River and Wujiang River.
Mojiang, located on the left bank of Beijiang River, originates from the top of cotton pit in Shixing County, flows from south to northShixing CountyShangjiangkou flows into Zhenjiang River.The catchment area is 1367 square kilometers, the river is 89 kilometers long, and the average gradient is 2.38 ‰.
Jinjiang, located on the right bank of Beijiang River, originated in Jiangxi ProvinceChongyi CountyZhudong'ao, flowing from north to south, flows into Baimangba, Qujiang CountyZhenjiang River。The catchment area is 1913 square kilometers, the river is 108 kilometers long, and the average gradient is 1.71 ‰.Renhua County Station (with a catchment area of 1476 square kilometers) has an average annual runoff depth of 989.0 mm and an annual runoff of 1.46 billion cubic meters.There is Danxia landform near Renhua.
Wujiang, also called Wushui.It is located on the right bank of Beijiang River, originates from Sanfeng Ridge, Linwu County, Hunan Province, flows into Guangdong Province in the east, joins Zhenjiang River at Shazhouwei, Shaoguan City, with a catchment area of 7097 square kilometers, a river length of 260 kilometers, an average gradient of 0.91 ‰, a watershed of up to 1902 meters, Lishi Station (with a catchment area of 6976 square kilometers) with an average annual runoff depth of 863.5 mm, and an annual runoff of 6.02 billion cubic meters,The average annual sediment discharge is 958000 tons, and the average annual erosion modulus is 137 tons/km2.The main tributaries areNanhuaxi。
Midstream section
Qingyuan Section of Beijiang River in Guangdong
The middle reaches is from the end of Shaoguan sandbar to Qingyuan Feilai Gorge. The river is 173km long, with an average gradient of 0.125 ‰. Most of the river valleys are U-shaped, and the river channels are generally straight. There are also four canyons, namely, Feilai Gorge at the upstream of Qingyuan, which is 9km long;The blind gorge between Yingde Boluo pit and Lianjiangkou is 6 kilometers long;Between Yingdeli Cave and Qingyuan Hengshi are Xianglu Gorge and Damiao Gorge, both of which are less than 100 meters long.The average width of the river surface is about 400 meters, and the depth of water in the low water season is 20-30 meters in the blind child gorge and Feilai gorge;The river channel with sandbanks is often less than 1m deep.In Yingde, there is a big cave in Baojing Palace.The main tributaries along the river in this section include Nanshui, Wujiang and Lianjiang.
Nanshui, located on the right bank of Beijiang River, originates fromRuyuan CountyAn Duntou flows southeast atQujiang CountyMengzhouba River flows into Beijiang River.The catchment area is 1489 square kilometers, the river is 104 kilometers long, and the average gradient of the river channel is 4.83 ‰.
Lianjiang, located on the right bank of the Beijiang River, originates from the Three Sisters Peak in Lianxian County, Guangdong Province, and the main stream flows southeast throughYangshan County、Yingde CountyIt joins Beijiang River at Jiangkouzui Village, Lianjiangkou Town, Yingde, with a catchment area of 10061 square kilometers (the largest tributary of Beijiang River), a river length of 275 kilometers, and an average gradient of 0.77 ‰.Gaodao Station (with a catchment area of 9007 km2) has an average annual runoff depth of 1162.3 mm, an average annual runoff of 10.5 billion m3, an average annual sediment discharge of 1.48 million tons, and an average annual erosion modulus of 164 tons/km2.Lianxian CountyThe above is called Xingzishui, also calledWenjiang。
Downstream section
Feilaixia toSanshui CountySixianjiao is a downstream section with a river length of 83km and an average gradient of 0.0815 ‰.This section is located in a plain area, with a wide river and many embankments on both banks. The 60 km long Beijiang levee is located in Sanshui County of this section.The main tributaries along the river include Pajiang River, Binjiang River and Suijiang River.
To damage the river, located on the left bank of Beijiang River, originated fromFogang CountyThe candle to the sky flows southwest through Qingyuan County and flows into Beijiang River at the mouth of Qingyuan River in flood season. It has a catchment area of 1386 square kilometers, a river length of 82 kilometers, and an average gradient of 1.74 ‰.Damiao Gorge (with a catchment area of 472 square kilometers).The average annual runoff depth is 1458.5 mm, and the annual runoff is 688 million cubic meters.The main tributaries are Niutou River, Sijiu River and Longnan River.
Binjiang, located on the right bank of Beijiang River, originates fromQingyuan CountyFog Mountain, flowing southeast toQingyuan CountyThe flywater flows into Beijiang River.The catchment area is 1728 square kilometers, the river length is 100 kilometers, and the average gradient of the river channel is 0.81 ‰.Zhukeng Station (with a catchment area of 1607 km2) has an average annual runoff depth of 1515.3 mm and an annual runoff of 2.44 billion m3.
Suijiang, located on the right bank of Beijiang River, originates fromLianshan CountyCatching Crows Top flows southeastGuangning County、Sihui County, onSihui CountyMafang flows into Beijiang River, with a catchment area of 7184 square kilometers, a river length of 226 kilometers, and an average gradient of 0.25 ‰.Shigou Station (with a catchment area of 6362 square kilometers) has an average annual runoff depth of 1094.8 mm and an annual runoff of 6.97 billion cubic meters.The area above Huaigao Village in Huaiji County is called Zhongzhou River, and it was called Suijiang River after confluence with Maning River.The upstream Huaiji area is a large area of flat land, the downstream Huaiji area enters the canyon area, and the downstream Sihui area is a plain.The main tributaries areFenggang Water。
Dongjiang River System
Dongjiang River System Map and Heyuan City Section
Dongjiang River originates from Xunwu County, Jiangxi Province（Xunwu County）Yaji bowl flows southwest through Guangdong ProvinceLongchuan County、Heyuan City、Zijin County、Huiyang County、Boluo CountytoDongguan CityShilong Town enters the Pearl River DeltaZengcheng CityYudong LianweiSoutheast inflowShiziyang。The catchment area is 35340 square kilometers, accounting for 5.96% of the total area of the Pearl River basin, and about 24.3% of the Pearl River basin area in Guangdong.The river is 562km long, with an average gradient of 0.388 ‰, an average annual runoff depth of 950.4 mm, and an average annual runoff of 25.7 billion cubic meters.The main stream is called above Longchuan Hehe DamFind Wu Shui, RemittanceBeiling waterLater, it was called Dongjiang.The terrain of the basin is high in the northeast and low in the southwest, and the highest elevation of the watershed is 1101.9 cubic meters.There are two large reservoirs in the basin, Xinfeng River and Fengshuba, with a total storage capacity of 15.84 billion cubic meters, accounting for 59% of the total storage capacity of 27 large reservoirs in the province. The catchment area of the two reservoirs is 11050 square kilometers, accounting for 40.9% of the area of the Dongjiang River basin.
stayLongchuan CountyThe upper reaches of the Dongjiang River is above the Fengshuba Reservoir, 3 kilometers west of Meishutang Village, and is called Xunwu Water.The river is 138km long with an average gradient of 2.21 ‰. It is located in a hilly area. The river valley is V-shaped and the water is shallow and the river is narrow.The main tributary is Beiling water.
Beiling water(also called Anyuan Water) is located on the right bank of the Dongjiang River and originates from JiangxiAnyuan CountyThe east flows southward into GuangdongLongchuan CountyIt joins Dongjiang River at Fengshuba Reservoir (formerly Heheba Village), 3 km west of Meishutang Village, Longchuan.The catchment area is 2364 square kilometers, the river is 140 kilometers long, and the average gradient is 1.98 ‰.The main tributary is Dingnan Water.
Midstream section
From the original Heheba Village in Fengshuba Reservoir to Guanyinge in Boluo County, it is the middle reaches of the Dongjiang River. The river is 232 kilometers long and the average gradient of the river channel is 0.31 ‰.The terrain below Longchuan gradually decreases. A plain appears on the right bank of Dongjiang River in the upstream of Guanyinge, while the left bank is still hilly.The main tributaries flowing into this reach along the river areLijiang, Xinfeng River, Qiuxiang River.
Lijiang, located on the right bank of Dongjiang River, originated fromHeping CountyYapoji, Liyuan Township, flows southeast to Dongshui Street, Heping County and into Dongjiang River.The catchment area is 1677 square kilometers, the river length is 100 kilometers, and the river slope is 2.2 ‰.
Xinfeng River, located on the right bank of Dongjiang River, originated fromXinfeng CountyYapo StoneHeyuan CityThe city flows into the Dongjiang River.The catchment area is 5813 square kilometers, the river is 163 kilometers long, and the average gradient of the river channel is 1.29 ‰.The average annual runoff depth of Xinfengjiang Reservoir Station (with a catchment area of 5734km2) is 1087.5mm, and the annual runoff is 6.22 billion m3.Existingxinfengjiang reservoir And hydropower stations.The main tributaries are Lianping River and Chuantang River.
Qiuxiang River, located on the left bank of Dongjiang River, originated fromZijin CountyLitou Stronghold, inHuiyang CountyThe estuary flows into the Dongjiang River.The catchment area is 1669 square kilometers, the river is 144 kilometers long, and the average gradient of the river channel is 1.11 ‰.
Downstream section
From Guanyin Pavilion toDongguan CityShilong is the downstream section of the Dongjiang River, 150 km long, with an average gradient of 0.173 ‰.Located in plain area, the river width increases, the flow rate slows down, and there are many sandbanks in the river channel. The sandbanks position changes after every flood, and the river bank is relatively stable with embankments.The main tributaries are Gongzhuang River, Xizhi River and Shima River.
Gongzhuang River, located on the right bank of Dongjiang River, originated fromBoluo CountyNuo Dou Bai flows into Dongjiang River at Mu Village, Taimei Town, Boluo County.The catchment area is 1197 square kilometers, the river is 82 kilometers long, and the average gradient of the river channel is 0.51 ‰.
Xizhi River, located on the left bank of Dongjiang River, originated fromHuidong CountyWuqinzhangHuizhou CityIt flows into Dongjiang River.The catchment area is 4120 square kilometers, the river is 176 kilometers long, and the average gradient of the river channel is 0.6 ‰.The basin is located in the center of rainstorm, with steep terrain in the middle and upper reaches and low-lying in the lower reaches.The average annual runoff depth is 900-1600mm.Baipenzhu Reservoir has been built.The main tributaries are Andun Water and Danshui River.
Shima River, located on the left bank of Dongjiang River, originated fromBao'an CountyBig skull, inDongguan CityJiantang Village, Qishi Town flows into Dongjiang River.The catchment area is 1249 square kilometers, the river is 88 kilometers long, and the average gradient of the river channel is 0.51 ‰.[5]
Rivers in the Pearl River Delta
Schematic diagram of the main stream inlets of the Pearl River system
The Pearl River Delta is a composite delta, which is located below Sixian of Xijiang River and Beijiang River, below Shilong of Dongjiang River and other rivers in the injection delta, mainly includingGaoming River, Shaping waterTanjiang River、Liuxi River、Shahe River、Xifu River、Zengjiang、Yayao River、Nangang RiverAnd only flows into the estuaryMaozhou River、Shenzhen RiverEtc.The catchment area of this area is 26820 square kilometers, accounting for 5.91% of the total area of the Pearl River basin, and 24.1% of the Pearl River basin area in Guangdong.Among them, the delta covers an area of 9750 square kilometers (8370 square kilometers for the west and north river deltas, and 1380 square kilometers for the east river delta), and the upper reaches of other rivers in the injection delta cover an area of 17070 square kilometers (10150 square kilometers for the west and north river deltas, and 6920 square kilometers for the east delta).
The river channels in the Pearl River Delta are meshed, and the river branches are interconnected vertically and horizontally. After the joint enclosure treatment, the total length of the watercourses in the current river network area is still more than 1600 kilometers.Finally, it will be injected into the South China Sea through 8 gates.According to statistics, the longitudinal channel curvature coefficient is 1.03-1.23, and the transverse channel curvature coefficient is 1.26-1.46.The longitudinal river width of the Northwest River Delta is 400-500 meters or 1600-1800 meters;The transverse river is 200-300 meters wide or 10-10 meters wide.The average density of natural river network is 0.81 km/km2.The river channel is of deep and narrow type.The main discharge channels are basically separate systems.
Pearl River Delta Water Network
Xijiang Delta Estuary Section
Xijiang River stretches from Sixianjiao Xijiaokou to Qirenshi, with a main stream length of 139km and an average gradient of -0.04 ‰.amongSixianjiaoXijiaokou toXinhui CountyNan'an (Tianhe), 57.5km long, is called the main stream waterway of Xijiang River;Nan'an Xinhui BaiqingtouXihai Waterway, 27.5km long;Baiqingtou to Enterprise People's ReputationKnife grinding gate water channel, 54 km long.
Gaoming River, located on the right bank of the main water channel of the West River, originated fromGaoming CountyTray top, atGaoming CountyHaikou monument flows into the main stream of Xijiang River.The catchment area is 1010 square kilometers, the river is 86 miles long, and the average gradient is 0.45 ‰.
Tanjiang River, located on the right bank of the main water channel of the West River, originated fromYangdong CountyThe main stream of Niuweiling flows from west to east, through Enping and Kaiping, to the south near Shuangshui, Xinhui County, and then flows into Yinzhou Lake at Shizui, Xinhui County, and then into the South China Sea from Yamen.The catchment area is 5068 square kilometers, the river length is 248 kilometers, and the average gradient is 0.45 ‰.The upstream is the rainstorm center area. The measured maximum 24-hour rainstorm is 656mm (Huangbutou Station), and the maximum three-day rainstorm is 848mm (Encheng Station), ranking first in all parts of the Pearl River basin.Cascade development has been implemented in the main stream, and 1030 large and small reservoirs have been built in the whole basin (including 3 large reservoirs and 12 medium reservoirs).
Beijiang Delta Estuary Section
From Sixianjiao Beijiaokou to the southNanhai CountyZidong, known as the main stream of the Beijiang River, is 25km long. There are three branches near Zidong, and the north branch isFoshan Waterway, the middle branch isTanzhou WaterwayThe south branch is Shunde Waterway;Mainstream from Zidong toShunde CountyZhang Song went to the river, calledShunde Waterway, the river is 48 km long;Zhang Songshanghe to Panyu Xiaohu Mountain YanweiShawan WaterwayThe river is 32km long.The river from Sixianjiao Beijiaokou to Yanwei is 105km long, with an average gradient of 0.0534 ‰.Mainstream is flooding into the tailShiziyangOut of Humen and into the South China Sea via Lingdingyang.Another branch flows throughJiaomen WaterwayandHong Qilithroughlintin Into the South China Sea.Eastern Beijiang distributarySouthwest Chung、Lubao ChungRemit firstLiuxi River, to the Pearl River (Guangzhou waterway)ShiziyangOut of Humen.
Main tributaries flowing into the Pearl RiverLiuxi River, located in the north of the Pearl River Delta, originated fromConghua CountyGuifeng Mountain flows southwest to GuangzhouBaiyun DistrictNangangkou turns southeastward and flows into the Pearl River at the White Goose Pond in Guangzhou.The catchment area is 3917 square kilometers, the river is 174 kilometers long, and the average gradient of the river channel is 0.8 ‰.
Dongjiang Delta Estuary Section
The Dongjiang River is divided into two branches below Shilong in Dongguan, passing through the north of Shilong to the mouth of Machong Chongkou in Dongguan and entering the Shiziyang Ocean. It is called the north main stream of the Dongjiang River, with a length of 42 kilometers and an average gradient of 0.000473 ‰;The other branch passes through the south of Shilong to the gorge mouth and the cold stream, and flows into Shiziyang in many river branches, called Dongjiangnan Branch.In general flood, the flow of the north main stream of Dongjiang River is greater than that of the south branch;In case of heavy flood, the two are basically close.There are five main waterways in the Dongjiang Delta, with a total length of 138 kilometers and a river network density of 0.88 kilometers per square kilometer.The main tributaries flowing into the Dongjiang Delta include Zengjiang River and Shahe River.
Zengjiang, located on the right bank of the north main stream of the Dongjiang River, originated fromXinfeng CountyQixing Ridge flows through Longmen and Zengcheng County, and joins the north main stream of Dongjiang River at Guanhaikou, Shitan Town, Zengcheng County. It has a catchment area of 3114 square kilometers, a river length of 206 kilometers, and an average gradient of 0.74 ‰.
Shahe River, located on the right bank of the north main stream of the Dongjiang River, originated fromBoluo CountyDushan, Henghe River, flows into the north main stream of Dongjiang River in Shiwan Town, with a catchment area of 1235 square kilometers, a river length of 89 kilometers, and an average gradient of 0.64 ‰.
In addition, the rivers that directly flow into the Pearl River estuary flow through Dongguan and Bao'an CountyMaozhou River, Gaoyi Bay flowing into Humen, with a catchment area of 371 square kilometers;Flow through Shenzhen and Hong Kong New TerritoriesShenzhen River, flowing into Shenzhen Bay, with a catchment area of 306 square kilometers.[5]
hydrographic features
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water level
The water level of all rivers in the Pearl River basin in Guangdong is corresponding to the rainfall. Generally, the high water level is from April to September, and the highest water level is from June to July.The highest water level of the East and North Rivers mostly occurs in June, while that of the main stream of the West River and Guangzhou Waterway is the highest in June and July, followed by August.
The main stream of the lower reaches of the Xijiang River is represented by Gaoyao Station. The average water level for many years (1931-1988) is 2.456 meters (the base level of the Pearl River, the same below), the highest measured water level over the years is 12.916 meters (July 5, 1949), and the lowest water level over the years is -0.304 meters (February 20, 1955).The measured variation of the highest and lowest water levels over the years is 13.220 meters.
The Beijiang River is represented by Shijiao Station. The average water level for many years (1924-1988) is 6.198m, the measured highest water level over the years is 13.958m (May 13, 1982), the lowest water level over the years is 3.588m (March 14, 1960), and the variation of the highest and lowest water levels over the years is 10.370m.
The Dongjiang River is represented by Boluo Station. The average water level for many years (1953-1988) is 6.49m, the measured highest water level over the years is 15.64m (June 16, 1959), the lowest water level over the years is 4.40m (December 31, 1984), and the variation of the highest and lowest water levels over the years is 11.24m.[5]
runoff
The average annual runoff of the Pearl River basin in Guangdong is 114.4 billion cubic meters.Among them: 25.1 billion cubic meters in the Dongjiang River, 45.7 billion cubic meters in the Beijiang River, 12.3 billion cubic meters in the downstream mainstream of the Xijiang River, and 31.3 billion cubic meters in the Pearl River Delta.The average annual runoff depth is 1020.6 mm, and the average annual runoff depth of each region is 800~1800 mm. The average runoff coefficient is 0.58, and the average runoff coefficient of each region is 0.5~0.7;The runoff modulus is 32.36 L/s · km2, and the runoff modulus of each region is 25.9~35.4 L/s · km2;The annual runoff coefficient is between 0.3 and 0.4;The absolute ratio of annual runoff is 6.78 for Dongjiang (Boluo Station), 4.34 for Beijiang (Shijiao Station) and 2.9 for Xijiang (Gaoyao Station).
The annual runoff distribution in the flood season (April to September) accounts for about 80% of the annual runoff, and the dry season (October to March) accounts for about 20% of the annual runoff.
The annual water inflow of the Pearl River into the sea is 326 billion cubic meters.[5]
silt
The average annual sediment concentration of the Pearl River is 0.11~0.64kg/m3.The river with the smallest sediment concentration is Tanjiang River (Huangbutou Station), 0.11kg/m3;The largest is Zhenjiang River in the upper reaches of Beijiang River, which is 0.32kg/m3, and Luoding River (Guanliang Station), a tributary of Xijiang River, which is 0.64kg/m3.
The annual average sediment concentration of each river increases from 0.13kg/m3 in the downstream to 0.27kg/m3 in the upstream of Dongjiang River;Beijiang River increases from 0.13kg/m3 in the downstream to 0.32kg/m3 in the upstream;The main stream of the lower reaches of the Xijiang River is 0.32kg/m3.
The interannual variation of sediment concentration in each river has little change in the mainstream of the lower reaches of the Xijiang River;Beijiang slightly increased in the 1960s compared with the 1950s (0.02 kg/m3), and remained unchanged in the 1960s and 1970s;The sediment concentration of Dongjiang River gradually decreased, which was related to the construction of Xinfeng River and Fengshuba Reservoir in the late 1950s and early 1970s respectively, and the increase of each river in the 1980s.
The seasonal variation of sediment concentration in the Pearl River is small in dry season and large in flood season;The maximum monthly average suspended load concentration occurs from April to June, most of which occurs in May.
The average annual sediment transport of the Pearl River is 85.79 million tons. Among the sediment transport of the Pearl River, the important sediment transport of the Xijiang Control Station accounts for 82.8% of the total sediment transport.
The annual variation of the sediment discharge of the Pearl River is larger in the 1970s than in the 1950s and 1960s at the Gaoyao Station of the Xijiang River;The annual sediment discharge of Shijiao Station in Beijiang increases year by year;The annual sediment discharge of Boluo Station on the East River gradually decreased, and by the 1980s, the annual sediment discharge of each river had basically increased to varying degrees.
The maximum multi-year average sediment transport modulus of the Pearl River is Luoding River (Guanliang Station), 516 tons/km2;The minimum is Dongjiang (Boluo Station), 117 tons/km2;Others are between 140~202 tons/km2.In the 1980s, sediment transport modulus generally increased compared with the annual average, especially in Dongjiang River and Beijiang River, which increased by more than 80%.[5]
Estuarine hydrology
Estuarine segmentation
In terms of estuaries and hydrology, estuaries refer to the transitional zone between rivers and seas.The estuarine area covers the area up to the farthest point where the river is affected by the ocean tide, and down to the seaside affected by the diffusion of river water.Accordingly, the upper boundary of the Pearl River Estuary can reach Sanrong Gorge in the West River, Sanshui in the North River, Jiangcun in the Guangzhou Waterway (the main stem of the Pearl River), and Shilong Yuanzhou in the East River.Sixian of the West and North Rivers and Shilong of the East River are near the mouth, with a single waterway, which is mainly affected by runoff.
West and North Rivers are below Sixianjiao, and Jiangmen, Waihai, Rongqi, Sanshan and Guangzhou are above the first line;The Dongjiang River is below Shilong, and the reach above the Xintang, Zhongtang and Dongguan line is the estuary. The flow is dispersed and reciprocating.
Below the estuary to the estuary is the coastal section outside the estuary. The upstream runoff has been dispersed and flattened so far, with weak impact and significant tidal effect.
In order to be consistent with the customary scope of the net river delta, the whole Pearl River Delta area below Sixian is called the estuary area.[5]
Runoff into the sea
The average annual inflow of the Pearl River from each entrance is 376.2 billion cubic meters at rising tide, and the average annual outflow of falling tide is 702.2 billion cubic meters. The corresponding net discharge into the sea is 326 billion cubic meters, of which Humen accounts for 18.5%, Jiaomen 17.3%, Hongqili 6.4%, Hengmen 11.2%, Modaomen 28.3%, Jiqimen 6.1%, Hutiaomen 6.2%, Yamen 6.0%.[5]
tide
The tides in the Pearl River Estuary belong to irregular semidiurnal tides.For the phenomenon of unequal diurnal tide, it generally decreases from the open sea to the shore and from the west coast to the east coast.The general ratio of islands off the Pearl River Estuary is 1.77;The ratio near the land bank (sampan island) is 1.15;The ratio in the west coast is 1.36 in Huangchong and 1.37 in the west fort;The ratio of the eastern coast is 1.21 in Chiwan and 1.20 in Nansha.
In the Pearl River Estuary, the solar tide and the lunar tide compound to form the synoptic spring tide, and the upper and lower chords, the solar tide and the lunar tide offset each other to form the upper and lower chords neap tide.
Runoff and typhoon have great influence on tide level.The highest tide level occurs in the flood season, with July as the highest and March as the lowest.There is little change between high tide and low tide.The water level variation of the highest and lowest values of each station over the years can reach about 10 meters at the top of the Pearl River Delta, including 10.13 meters in Makou, 10.84 meters in Sanshui and 6.81 meters in Shilong, Dongjiang;The tide stations at each entrance are: Humen is 4.26m, Jiaomen is 3.88m, Hongqili is 3.66m, Hengmen is 3.47m, Modao is 3.23m, Jiti is 3.52m, Hutiao is 3.87m, Yamen is 4.01m.
The Pearl River Estuary is a weak tidal estuary, and the tidal range along the coast in the east is generally larger than that in the west.The tidal range near Humenkou is the largest, reaching 3.66 meters in Dongguan Taiping, with an average of 1.70 meters for many years;The second is Yamenkou. The maximum height of Huangchong is 2.63 meters, and the average height for many years is 1.24 meters;The tidal range at Modao Gate is the smallest, and the maximum at Denglong Mountain is only 2.04m on average, 0.86m on average.The Lingding Bay at the Pearl River Estuary has an increasing tidal range from outside to inside, and the tidal range on the east bank is larger than that on the west bank. The maximum tidal range from Chiwan in Shenzhen to Taiping Town in Dongguan on the east bank has increased from 3.15m to 3.66m on average for many years (calculated value);On the west bank, the multi-year average maximum tidal range from Xiangzhou to Jiaomenkou (Nansha) in Zhuhai City is only 2.50-2.80 meters, and the average tidal range is only 1.14-1.36 meters.
In the river network area of the Pearl River Delta, the general trend of tidal range is to decline upstream. The average maximum tidal range for many years is 0.74 meters from 2.04 meters of Denglong Mountain at Modaomenkou to 0.74 meters at Makou in Xijiang River;The Beijiang River system decreases from 2.25m in Hengmen and 2.65m in Jiaomen Nansha to 0.74m in Sanshui;The Dongjiang River system is reduced from 3.12 meters in Sishengwei, Dongjiangkou, and 2.90 meters in Dasheng to only 0.90 meters in Shilong.Over the years, the average tidal range of Xijiang River decreases from 0.86 meters of the Denglong Mountain in Modaomen to 0.26 meters in Makou;The Beijiang River system is also reduced to 0.26 meters from 1.10 meters in Hengmenkou and 1.36 meters in Nansha in Jiaomenkou to Sanshui;The Dongjiang River system is reduced from 1.63m in Sishengwei and 1.61m in Dasheng, Dongjiangkou, to 0.28m in Shilong.The tidal range of the whole delta network area is larger in the east than in the west, and decreases upward along the river, and is faster in the east than in the west.
The duration of ebb and flow tides in the Pearl River estuary area is not equal, generally the ebb tide duration is longer than the flood tide duration.The ebb tide lasts longer than the flood tide, except for the Dangan Islands at the mouth of the Pearl River and the sea area near Wailingding Island.The ebb tide lasts for 7 hours along each gate, and gradually increases along the river. The fastest increase is in the Dongjiang River. The ebb tide lasts for 9 hours when it reaches Makou (Xijiang River), Sanshui (Beijiang River) and Shilong (Dongjiang River) at the top of the river network.The average duration of rising tide at each entrance is 5 hours and 30 minutes, and it gradually decreases upstream along the river.The decline of Dongjiang River is the fastest, and that of Makou, Sanshui and Shilong at the top of the river network area is reduced to 4 hours, 30 minutes and 4 hours respectively.
When two upwelling currents (or downwelling currents) or one upwelling current meets the other downwelling current, a tide meeting point is formed. There are more than 30 tide meeting points in the Pearl River Delta.At the tide meeting point, the water flow is relatively slow, and a large amount of sediment brought by the tide is deposited, which makes the nearby riverbed silted up.[7]
Sediment discharge
The average annual sediment discharge of the Pearl River is 85.79 million tons, which has silted up in the Pearl River estuary area, promoting the formation and development of the Pearl River Delta.According to analysis and measurement, in the past 5000 years, the deposition rate was 2.180 mm/year in the first 2500 years, and 2.710 mm/year in the last 2500 years. The latter was 19.5% larger than the former.Before the Tang Dynasty (about 1000 years ago), the average advancing speed of the delta plain was 9.1 meters per year (in the west and north river deltas) and 7.25 meters per year (in the east river delta);After the Tang and Song Dynasties (about 1000~700 years ago), it was 37.3 m/year and 14.5 m/year respectively;In the past 100 years, 63.6 m/year in Wanqingsha and 121.7 m/year in Lantongsha.[5]
water disasters
There is an average flood and drought disaster in the Pearl River basin of Guangdong Province in about three years.
flood
The floods in the Pearl River are mainly caused by rainstorm, and the rainstorm causes of large floods are mainly frontal, southwest trough, tropical depression and typhoon.Due to the wide drainage area, heavy rainfall intensity, fast flood convergence in the upper and middle reaches of mountains and hills, and no lakes for regulation and storage in the middle reaches, large areas of continuous torrential rain often form floods with high peak, large volume and long duration, endangering low-lying, populous, economically developed towns and vast farmland along the middle and lower reaches of the river, restricting economic development and affecting social stability.[8]
The floods in the Pearl River basin were first recorded before 1900, which can be traced back to the first year of Han Yongchu (107 years).The later major flood disasters included the eighth year of Taiyuan in the Eastern Jin Dynasty (383 years), the fourth year of Xianqing in the Tang Dynasty (659 years), the second year of Zhidao in the Northern Song Dynasty (996 years), the fifth year of Hongzhi in the Ming Dynasty (1492 years), the fourteenth year of Jiajing in the Ming Dynasty (1535 years), the fifth year of Longqing in the Ming Dynasty (1571 years), the fourteenth year of Wanli in the Ming Dynasty (1586 years), the fourteenth year of Wanli in the Ming Dynasty (1616 years), the fortieth year of Kangxi in the Qing Dynasty (1701 years)In the 43rd year of Kangxi's reign (1704), the 34th year of Qianlong's reign (1769), the 38th year of Qianlong's reign (1773), the 59th year of Qianlong's reign (1794), the 13th year of Daoguang's reign (1833), the 6th year of Xianfeng's reign (1856), the 3rd year of Tongzhi's reign (1864), the 3rd year of Guangxu's reign (1877), and the 11th year of Guangxu's reign (1885), the 13th year of Daoguang's reign was the most serious.[9]
According to the flood records from 1900 to 1949, the major floods in the Xijiang River included the 28th year of the reign of Emperor Guangxu of the Qing Dynasty (1902), the 34th year of the reign of Emperor Guangxu of the Qing Dynasty (1908), the 3rd year of the Republic of China (1914), the 4th year of the Republic of China, the 13th year of the Republic of China, the 15th year of the Republic of China, the 20th year of the Republic of China, and the 38th year of the Republic of China;Beijiang was in the 3rd, 4th, 13th, 20th, 36th and 38th years of the Republic of China;Dongjiang took 36 years of the Republic of China as the year of catastrophic flood.
On average, there is a flood in the Pearl River Delta in about three years, and the affected farmland area exceeds 1 million mu.In terms of the whole basin, the floods in the 4th year of the Republic of China (1915) and the 38th year of the Republic of China caused the heaviest losses.The disasters of these years are reflected in local chronicles, newspapers at that time and some historical materials.For example, the flood in the 4th year of the Republic of China flooded Guangzhou for 7 days.According to the Guohua Daily at that time, "... the water on No. 13 suddenly rose, which was even worse than the previous day. The Long Causeway reached three feet, while the water depth around Xiguan was more than ten feet, or several feet. The worst was in Fengyuan, Duobao, and Baohua streets, where the water was the deepest. There were countless collapsed houses, and people who were crushed or drowned were unknown...".According to statistics, in the Pearl River Delta alone, 6.48 million mu of farmland was flooded, 4.5 million mu of farmland was lost, more than 3.78 million people were victims, and more than 100000 people were killed or injured.
The flood in the 38th year of the Republic of China (1949), according to the report of the then Guangdong Business Daily, "all the major dikes in the lower reaches of the Xijiang River in the province (referring to Guangdong Province) have collapsed successively. Qingyuan, Yingde, Huaxian, Sanshui and other counties in the Beijiang River and Xiaobeijiang River have been hit by the flood at the same time, soaking fields and losing houses.As the last reaches of the West and North Rivers, even the rice producing areas in the Pearl River Delta are also baptized by floods... "According to the statistics of the former Pearl River Water Conservancy Bureau, the Pearl River Delta alone has a disaster area of more than 2.5 million mu and more than 1.4 million victims.
After 1950, there were records of major flood disasters in the Pearl River Basin in Guangdong Province. The lower reaches of the Xijiang River were 1968, 1973 and 1976;Beijiang in 1964, 1968, 1982 and 1985;Dongjiang in 1959, 1964 and 1979;Tanjiang in 1965;1983 in the Pearl River Delta.
In August 1986, Guangdong Provincial Hydrological Station compiled Guangdong Water Resources, which recorded that "in 1959, a flood with a return period of more than one hundred years occurred in the Dongjiang River and affected 1.3 million mu of farmland. In 1979, a flood with a return period of two hundred years occurred in the Xizhijiang River due to the combined impact of typhoon and cold air, which destroyed more than 80000 houses and 1 million mu of farmland." According to the People's Pearl RiverIn the fifth issue of 1982, it was recorded that "before and after May 12, 1982, more than ten counties in the northwest of Guangdong Province experienced heavy rain, the water level of the West and North Rivers rose sharply, the dike was broken due to lack of enclosure, and Yingde, Qingyuan, Yangshan, Lianxian, Sihui five counties and more than 4000 villages were flooded.According to preliminary statistics, 1.09 million people were affected, 430 people died, more than 1.79 million mu of farmland was flooded, more than 46000 houses collapsed, and 84 dikes were breached.The old Hengshi Shengping section of Beijing Guangzhou Railway was severely damaged.According to the data of Guangdong Provincial Hydrological Station, "the flood caused a direct loss of 4.4 billion yuan to industry and agriculture, and the Beijing Guangzhou Line stopped operating for 23 days." On September 9, 1983, the strong typhoon 8309 hit the Pearl River Estuary head-on,According to the data of Guangdong Provincial Hydrological Station, "the sea walls of Zhuhai, Panyu, Zhongshan, Dongguan and other counties and cities are generally overtopped and burst, large areas of villages and cultivated land are vast, and the roads along the river and low-lying places in Guangzhou are flooded to varying degrees below 1 meter".[5]
According to incomplete statistics of historical data, since the Han Dynasty, basin floods have occurred more than 400 times. The major floods in the past 100 years include the Xijiang River floods in 1915, 1968, 1988, 1994, 1996, 1998 and 2005, the Dongjiang River floods in 1959, the Beijiang River floods in 1982, and the Nanpan and Beipan River floods in 1991.The probability of flood is increasing day by day, and the loss caused by flood is also increasing with the increase of population and economic development.According to the statistics of Guangdong and Guangxi provinces (autonomous regions), the direct economic losses caused by floods in the past decade from 1988 to 1998 reached 187.3 billion yuan, with an average annual loss of 18.4 billion yuan.[10]
drought
In the Pearl River basin, northern Guangdong is prone to autumn drought, southern central Guangdong is prone to spring drought, and the Xijiang River valley region is prone to continuous autumn and spring drought.There are 77 years of drought in the whole basin recorded in history, and the drought in the 21st year of Guangxu (1895) of the Qing Dynasty was the most serious;The ninth year of Jiajing in the Ming Dynasty (1530), the sixteenth year of Chongzhen in the Ming Dynasty (1643), and the 32nd year of the Republic of China (1943) followed.
According to statistics, in the 21st year of the reign of Emperor Guangxu of the Qing Dynasty (1895), the area of drought affected farmland in the Pearl River basin of Guangdong reached 10.17 million mu.
After 1949, there was an average of one drought every three years, and the more serious disasters were in 1955, 1963 and 1977.
From the autumn of 1954 to April of 1955, the drought in 1955 lasted for a long time without rain, and the rainfall was more than 50% less than that in normal years;The drought in 1963 lasted from October 1962 to May 1963, and there was almost no permeable rain. The rainfall was about 50% less than that in normal years, while the rainfall from March to May 1963 was 60% to 95% less than that in normal years. The return period exceeded the 100 year return period, and even reached the 200 to 300 year return period.According to records, the drought area of the lower reaches of the Xijiang River, Beijiang River and Dongjiang River in 1963 was 10.1709 million mu, accounting for 43.8% of the total cultivated land area of 23.27 million mu in the Pearl River basin of Guangdong.The drought in 1977 lasted for 18 months from October 1976 to April 1978, and the Pearl River Delta was the main drought area in the basin.[5]
Basin overview
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Regional scope
The Pearl River basin is located between 21 ° 31 ′~26 ° 49 ′ north latitude and 102 ° 14 ′~115 ° 53 ′ east longitude.The basin starts from Nanling in the north and ends at Yunwu, Yunkai, 60000 and 100000 mountains in the south;From Lianhua Mountain in the east to Wumengshan Mountain in the west.It is located in Yunnan, Guizhou, Guangxi, Guangdong, Hunan, Jiangxi and other six provinces and regions. The upstream of its secondary tributary Zuojiang River is in Vietnam.The drainage area is 453690 square kilometers, of which the domestic part is 442100 square kilometers, accounting for 4.6% of the total area of the country.The annual runoff is second only to the Yangtze River, and its length and drainage area rank fourth in China.[7]
climatic conditions
The Pearl River basin has a subtropical climate, with an average temperature of 14~22 ℃ for many years.The interannual change is not large, but the regional difference is large.The highest temperature is 42 ℃, and the lowest is - 9.8 ℃.The relative humidity for many years is between 71% and 82%.The annual average wind speed is 0.7~2.7 m/s, and the maximum wind speed is 30 m/s.The annual average sunshine duration is 1282~2243 hours, including 2243 hours for Luliang of Nanpan River and 1282 hours for Tiane of Hongshui River.The maximum sunshine distribution in the year is in July and August, about 180 hours per month;At least in February and March, about 1200 hours per month.The basin has abundant rainfall, with annual average precipitation of 1470mm.The precipitation decreases gradually from east to west. Generally, there is more precipitation in mountainous areas and less precipitation in plain valleys.The precipitation of Shangping Station in Longchuan County at the upstream of Zengjiang River in the basin is the largest, with an average annual precipitation of 2574mm;The annual average precipitation of Yuguopu Station in Mengzi County in southeast Yunnan is the smallest, 720mm.[12]
The Pearl River is located on the north and south sides of the Tropic of Cancer and near the South China Sea. The monsoon has a strong impact. The climate is warm in winter and long in summer, dry in winter and wet in summer.It belongs to the tropical and subtropical monsoon climate zone. The climate is mild and rainy. The average temperature for many years is between 14~22 ℃, with little interannual change.The rainfall is abundant, with an average annual rainfall of 1525.1 mm for many years.Rainfall decreases from east to west.The time distribution of precipitation is unbalanced, and the precipitation in rainy season (April to September) can account for more than 80% of the whole year.The disastrous climate is seriously harmful. The wet season rainfall is too concentrated and the rainfall intensity is high. The one-time continuous rainfall in some areas can reach more than 400 mm, so that the river valleys and plains are prone to flood disasters, and the mountains are prone to water and soil loss;The precipitation in dry season is obviously less, and the spring drought is prominent, which has a greater impact.The southeast coastal area is a high frequency area where tropical cyclones pass through, with an average of 6 to 9 impacts every year. July to September is the high frequency season when tropical cyclones attack.[11]
Geomorphic features
The Pearl River Basin is high in the northwest and low in the southeast.The highest point of watershed is Wumeng Mountain, 2853m above sea level;Mountains and hills account for 94.4% of the total area.It is located in the subtropical monsoon humid climate zone.[5]
The Pearl River basin is mostly mountainous and hilly, accounting for 94.5% of the total area, while the plains are small and scattered, accounting for only 5.5%.The overall terrain is high in the northwest and low in the southeast.The northwest is the Yunnan Guizhou Plateau with an average altitude of 1000~2000 meters, on which there are basins and lake groups.There are many rapids waterfalls at the edge of the plateau, among which the Huangguoshu Waterfall on the Baishui River, the source of the Dabang River in the Beipan River, is the most famous.To the east of the Yunnan Guizhou Plateau, there is a low mountain and hill with an altitude of about 500 meters, called the Liangguang Hill.There are also many mountains with an altitude of up to or more than kilometers between low mountains and hills, and many basins and valleys are distributed at the same time.Limestone is widely distributed in Guangxi and the eastern part of the Yunnan Guizhou Plateau. Strange stone forests, deep caves and underground rivers can be seen everywhere. The stone forests in Yunnan and the mountains and waters in Guilin are the most typical.The alluvial plain at the lower reaches of the Pearl River is the famous Pearl River Delta, where rivers and seas meet, river networks crisscross, and flat and green fields are beautiful and rich, with the unique style of southern water towns.
Most of the coastal areas of Guangdong and Guangxi are hilly lands, with the terrain high in the north and low in the south. There are a series of middle and low mountains along the coast, which serve as the boundary between the coastal rivers and the Pearl River system.There are alluvial plains or deltas of different sizes distributed at the estuaries of coastal rivers, of which the Hanjiang Delta is the largest.Coastal platforms are mainly distributed in Leizhou Peninsula, Hailufeng in eastern Guangdong and western Huilai.Hainan Island is the second largest island in China, with an area of 33900 square kilometers. Facing the Leizhou Peninsula, the terrain is high in the center and low around, with platforms and plains accounting for 65% of the total area, mountains and hills accounting for 35%. Basalt is widely distributed in the north, and a complete volcanic crater is reserved.
Resources
land resource
The total area of the Pearl River basin is 796300 square kilometers, with a total cultivated area of 95.6 million mu and a paddy field area of 60.4 million mu, accounting for 11% of the total area of the region.Among them, the land resources in the Pearl River basin are 663 million mu, the total cultivated land area is 72 million mu, the paddy field area is 39.6 million mu, and the forest land is 189 million mu. The cultivated land rate is lower than the national average. The per capita land ownership in the basin is only 93100 mu, about 3/5 of the national per capita land ownership.[11]
water resource
The total amount of water resources in the Pearl River basin is 518.2 billion cubic meters, of which the total amount of water resources in the Pearl River basin is 336.7 billion cubic meters. Its water volume ranks second among the seven major rivers in China, only second to the Yangtze River.According to the population in 2000, the per capita water resources in the basin are 3093m3/person, higher than the national average.However, about 80% of the rainfall is concentrated in the flood season, resulting in uneven distribution of surface runoff within the year. The runoff in the dry season only accounts for about 20% of the whole year.Affected by the topography and monsoon activities, there are obvious high and low value areas of runoff in the basin. High value areas such as the upper and middle reaches of the Gui, Liu and He Rivers, the southeast of Hainan, and the middle and lower reaches of the Beijiang River have an average annual runoff depth of 1000~1600 mm;Low value areas, such as southeast Yunnan, the upper reaches of the Nanpan River, the upper reaches of the Red River and river valleys, are only 50-300 mm.Due to the uneven distribution of water resources in time and space, frequent floods, floods and droughts in the basin, it is difficult to allocate water resources.
The Pearl River is rich in runoff and water resources. The hydropower installed capacity that can be developed in the whole basin is about 25.12 million kilowatts, and the annual power generation can reach 116.8 billion kilowatt hours.Among them, the Hongshui River in the Xijiang River has concentrated fall, large flow and superior development conditions, which is known as the "rich mine" of hydraulic resources.
There are 1088 navigable rivers in the basin with abundant water volume, stable river courses and good shipping conditions. The total navigable mileage is 14156 kilometers, accounting for about 13% of the national navigable mileage. The annual freight volume is second only to the Yangtze River.
mineral resources
There are 58 kinds of proven mineral resources in the Pearl River basin, including 25 kinds of coal, iron, sulfur, tin, tungsten, aluminum, manganese and other precious minerals with ore reserves of more than 100 million tons, as well as gold, uranium, titanium, niobium, tantalum and other precious minerals.More famous mining areas include Liupanshui Coal Mine in Guizhou, Nandan Dachang Mine, Pingguo Dachang Mine, Daxin Xialei Manganese Mine, Xiangzhou Barite Mine, gold mine in southeast Wuzhou, ilmenite in Cenxi, Yunfu Pyrite in Guangdong, Gejiu Tin Mine in Yunnan, etc.In addition, the South China Sea outside the mouth of the Pearl River is rich in oil and natural gas.[11]
Biological resources
According to the Plan for the Protection of Aquatic Biodiversity in Key Watersheds jointly issued by the Ministry of Ecology and Environment, the Ministry of Agriculture and Rural Affairs and the Ministry of Water Resources in 2018, there are 425 species of fish, 210 species (genera) of planktonic algae, 410 species (genera) of zooplankton, 268 species (genera) of benthos and 129 species of aquatic vascular plants in the Pearl River Basin according to incomplete statistics.There are Chinese sturgeon, Chinese white dolphin, turtle, flower eel, barbel, giant salamander and other national key protected animals in the basin, and about 200 kinds of endemic fish, such as southern wave fish and Hainan sea buckthorn.At present, there are 44 aquatic biological and inland wetland nature reserves and 27 national aquatic germplasm resources reserves in the Pearl River basin.[14]
socioeconomic
The total population of the Pearl River basin is 89.8 million. There are many ethnic groups in the basin, including more than 50 ethnic groups.The main ethnic groups are Han, Zhuang, Miao, Buyi and Maonan, among which Han people are the most, followed by Zhuang people.The coastal open port cities in the Pearl River basin include Guangzhou, Zhanjiang and Beihai, and the cities in the special economic zones include Shenzhen, Zhuhai and Shantou. Hainan Province is the largest special economic zone in China. The Pearl River Delta is a coastal economic development zone, and has formed a city cluster in the Pearl River Delta with Guangzhou as the center, including Shenzhen, Zhuhai, Foshan, Jiangmen and dozens of small and medium-sized towns around,It has the highest level of urbanization in China.[11]
According to statistics in 2000, the total annual population of the Pearl River basin is 168 million (excluding Hong Kong and Macao), with a GDP of 1330 billion yuan.The secondary and tertiary industries are mainly distributed in the river basin. In terms of the GDP composition in 2003, the primary industry accounted for only 13%, while the secondary and tertiary industries accounted for 46% and 41% respectively.
Due to geographical location, resource and environmental constraints and historical reasons, the regional economic development in the basin is extremely uneven, and the gap between rich and poor is wide.Among them, Guangdong Province, which is located in the lower reaches, has seized the favorable opportunity of reform and opening up by virtue of its geographical advantages and resource advantages adjacent to Hong Kong and Macao to develop a characteristic economy led by light manufacturing and high-tech industries, with a GDP of 966.2 billion yuan, accounting for 73% of the total GDP of the basin;According to the per capita level, in 2000, Guangdong, the province (autonomous region) with the highest per capita GDP in the basin, was more than 7 times that of Guizhou, the lowest, with a huge gap, and the per capita GDP in the Pearl River Delta region was more than 15 times that of the upper reaches of the basin.The Pearl River Estuary accounts for less than 0.3% of the country's territory and 1.5% of the population, creating 7.5% of GDP and 33% of the total export volume.The per capita GDP has exceeded 30000 yuan, ranking first in the country.
Governance development
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Hydropower development
Distribution of Hydropower Projects in the Pearl River System
The Pearl River is rich in runoff and water resources. There are 570 rivers with theoretical reserves of water resources of 100000 kilowatts and above, with a total theoretical reserves of 46.454 million kilowatts;2504 hydropower stations with a single installed capacity of 5000 kilowatts and above can be developed by technology, with a total installed capacity of 39.05 million kilowatts and an annual generating capacity of 168.2 billion kilowatt hours;There are 2263 economically developable hydropower stations with a total installed capacity of 37.321 million kilowatts and an annual generating capacity of 160.6 billion kilowatt hours.[11]
By the end of 1985, 13657 large and small hydropower stations with a total installed capacity of 3.588 million kilowatts had been built in the whole basin, including two large hydropower stations with a single installed capacity of more than 250000 kilowatts, with a total installed capacity of 692500 kilowatts and an average annual generating capacity of 3.085 billion kilowatt hours;There are 14 medium-sized hydropower stations with a total installed capacity of 1.0368 million kilowatts and an average annual generating capacity of 4.777 billion kilowatt hours.By the end of 1995, there were six large hydropower stations with a single installed capacity of more than 250000 kilowatts in the basin, with a total installed capacity of 4.5825 million kilowatts;There are 33 medium-sized hydropower stations with a total installed capacity of 25000-250000 kilowatts.
By the 1980s, Dazhai and Lubuge hydropower stations were built in 1978 and 1991 respectively in the Huangni River cascade, the largest tributary of the Nanpan River.Hongshui River is planned to be developed at 10 levels, namely Tianshengqiao Level I (1.2 million kilowatts in Bapan), Tianshengqiao Level II (1.32 million kilowatts in Basuo), Pingban (320000 kilowatts), Longtan (4 million kilowatts), Yantan (1.2 million kilowatts), Dahua (600000 kilowatts), Bailongtan (180000 kilowatts), Otan (560000 kilowatts), Qiaogong (500000 kilowatts), Datong (1.2 million kilowatts).There are Yantan, Bailong Beach, Dahua, Aitan and Tianshengqiao two levels built.The Mashi Power Station was built on the Liujiang River, a tributary of the middle and lower reaches of the Xijiang River, and was completed in 1977.Xijin and Guiping power stations have been built in Yujiang.Zhaoping Hydropower Station on the Guijiang River was completed.Hejiang has built Hemianshi, Baigou and Duping power stations.There are three power stations in Beijiang, namely Mengzhouba, Baishiyao and Feilaixia.Feilaixia Hydropower Station is a key project in the main stream of the Beijiang River and a hub for comprehensive utilization of flood control, navigation and power generation.Pillow Village and Maple Dam in the main stream of Dongjiang River have been built.[12]
flood control works
The cultivated land in the Pearl River basin threatened by flood tide is 926600 hectares, and the affected population is 20 million. The Pearl River flood is mainly concentrated in the confluence zone of the Pearl River Delta, Xunjiang River, Liujian River and Qianjiang River.These areas are densely populated and economically developed. Although most of them are protected by dikes, the flood control standard is not high. Except the Beijiang Dike in Guangzhou, which defends the flood with a return period of 20 years, most of them only defend the flood with a return period of 10 years.According to the policy of "combining embankment with reservoir, combining discharge with storage, and focusing on discharge", three flood control projects with embankment and reservoir were planned in the 1980s:
(1) The levees and reservoirs in the middle and lower reaches of the West and North Rivers are combined with flood control works.The construction of Feilaixia Reservoir in the middle and lower reaches of the Beijiang River can control a drainage area of 34097km, accounting for 73% of the area of the Beijiang River, mainly protecting Guangzhou City and the delta in the lower reaches of the Beijiang River. The benefit area is 106600 hectares of arable land, with a population of 3.38 million.The Feilaixia Reservoir, together with the reinforcement of the Beijiang River levee, can prevent the once-in-a-century flood and enable Guangzhou to withstand the 300-500-year flood from the Beijiang River.The Longtan Reservoir will be built on the Hongshui River in the upper reaches of the Xijiang River, with a drainage area of 98500 kilometers and a flood control storage capacity of 7 billion cubic meters.The Datongxia Reservoir will be built in Qianjian, with a controlled drainage area of 197755 km and a flood control storage capacity of 2 billion m.The joint operation of Longtan Reservoir and Datongxia Reservoir can effectively control the flood in the main stream of Xijiang River.The flood control engineering system composed of the above three reservoirs and corresponding embankments can ensure the safety of flood control in Guangzhou and key areas of the delta.
(2) Flood control engineering system combining dyke and reservoir in the middle and lower reaches of Yujiang River.The construction of Baise Reservoir in Yujiang River controls a drainage area of 19600km. Through reservoir regulation, the flood control standard of Nanning can be raised to a 50 year return period. Laokou Reservoir will be built in the future, controlling a drainage area of 73344km, accounting for 99.5% of the drainage area above Nanning. The combined use of the two reservoirs can make the flood control standard of Nanning reach a 100 year return period.
(3) The levees and reservoirs in the middle and lower reaches of the Dongjiang River are combined with the flood control engineering system. The control area of the built Xinfeng River, Fengshuba and Baipenzhu reservoirs is 11740km, accounting for 43.5% of the drainage area.The combined use of three reservoirs and embankment strengthening can raise the flood control standard of the middle and lower reaches of the Dongjiang River to the once-in-a-century flood.
The easy to salvage areas in the Pearl River basin mainly include the lower reaches of the Pearl River and the delta, the coast of the Xijiang River and the coast of the Xunjiang River.The above three waterlogging prone areas cover an area of 342000 hectares, of which 20% have not yet been harnessed and 80% have been preliminarily harnessed.It is planned to upgrade the installed capacity of the electric platoon to 176000 kw. After the key control, the area of waterlogged farmland will reach 324000 hectares, accounting for 94.7% of the area that should be controlled.[13]
Shipping situation
According to the statistics in 1980, there were 1088 navigable rivers in the Pearl River basin, with a navigable mileage of 14156 kilometers, including 79 major channels and 7154 kilometers of navigable mileage.The channel for 1000 ton ships is 757 kilometers long, 948 kilometers for 300~500 ton ships and 1546 kilometers for 100~300 ton ships.3000-5000 ton seagoing ships are available from Guangzhou to Huangpu, and 10000-25000 ton ocean going ships are available from Huangpu to Pearl River.[13]
Irrigation water supply
In 1985, there were 4.656 million hectares of cultivated land in the whole basin, with an effective irrigation area of 2.856 million hectares, and the irrigation rate of cultivated land was 61%, including 2.292 million hectares of protected irrigation area, with a protected irrigation rate of 49%.By 2000, the planned irrigation area will be 3.51 million hectares, with the irrigation conservation rate of 75%.
In order to solve the water supply problem in Hong Kong, the Shenzhen Reservoir was built in 1960, supplying 18.99 million cubic meters of water to Hong Kong every year;In 1965, the Dongjiang River Water to Shenzhen Reservoir Project via Shima River was built, increasing the water supply to Hong Kong to 68 million cubic meters every year. In 1978, the first phase of the expansion project was completed, increasing the water supply to 144 million cubic meters;In 1987, the second phase expansion was completed, and the annual water supply increased to 430 million cubic meters.[12]
