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Lijiang River belongs to the Xijiang River system in the Pearl River Basin, which is the general name of the upper reaches of Gui Jiang, a tributary, and is located in the northeast of Guangxi Zhuang Autonomous Region. In the traditional sense, the starting point of Lijiang River is Maoershan, Yuechengling, the source of Gui Jiang, and the modern hydrology is defined as Lingqukou, Rongjiang Town, Xing 'an, and the end point is Pingle Sanjiangkou. The upper reaches of Lijiang River are Darong River and the lower reaches are the traditional names of Gui Jiang. Lingqu Estuary is the dividing point between Darong River and Lijiang in Gui Jiang, while Lipu River and Gongcheng Estuary are the dividing points between Lijiang and Gui Jiang. The total length of Lijiang River 164 km. The riverbed along the river is mostly pebbles, with little sediment and clear water quality, and the banks are mostly karst landforms. The famous landscape of Guilin lies on the Lijiang River, which is rich in tourism resources.

Lijiang River, the general name of the upper reaches of Gui Jiang, a tributary of Xijiang River (the main stream of the upper reaches of the Pearl River), is located in the northeast of Guangxi Zhuang Autonomous Region. Lijiang River originates in the north of Maoershan, Huajiang Township, Xing 'an, Guangxi Zhuang Autonomous Region, and south of Laoshan boundary, with an altitude of1.732m (yellow sea bottom). Wugui River, the main source of Lijiang River, joins Longtang River in the south and Heikong River in the east. When these three rivers meet, they are called Liu Donghe. It flows south to Simenkou to join the Huangbaijiang River and Chuanjiang River, which is called Darongjiang River, and then joins Linghe River near Rongjiang Town, which is called Lijiang River. Lijiang River flows through lingchuan county and Guilin and joins Gongcheng River in the north of pingle town, Pingle County, with a total length of164km. Pingle town is hereinafter referred to as Gui Jiang. The river continues to flow south to Wuzhou and into Xijiang River. [ 1]

In xing an, the mouth of Rongjiang Town is connected with the Lingqu of the ancient canal, which is the starting point of the Lijiang River (ancient hydrology thought that Lingqu was the upper source of the Lijiang River [3]), and then it is connected with Xiaorongjiang River and left the country.

In lingchuan county, it entered the territory in Xiaorongjiang Village. Lijiang River basin covers an area of 2 173.29 square kilometers. The total length is 45km, which is divided into two sections: the upper section is 33.5km, and the average width of the river surface is160m. Starting from Xiaorongjiang Village, it flows through Xiabei, Yantou, Sanjie, Fuqiudu, Dutou, Shuangtan, Cuijiawei and Sanchawei. It has collected Baiyun River, Lujiang River, Ganjiang River, Waterfall River, Sanyuanhe River and Gan Tang River, and flowed into Guilin from Qin Xia to Dadianwei. The lower section 1 1.5km, the average width of the river surface is 220m, and the river bottom is pebbles mixed with sand and silt. From Shanglijiao Village in Dawei Town to Nancun Village via Ganxing and Dawei Town, it connects with the Yellow River, Jiansha River and Chaotian River, flows southward to Qingshuitan to connect with ancient water, and leaves the suburbs of Guilin and Xiayangshuo County. [4]

In the urban area of Guilin, the Lijiang River enters the urban area of Guilin at Qinjia, lingchuan county, passes through the urban area from north to south, flows to Douji Mountain after meeting in taohuajiang, winds south after passing through Dawei Town, Lingchuan, enters Yangshuo in Yan Guan, Caoping Township, and flows through the urban area for 49.3 kilometers. Guilin Hydrological Station (at the end of Zhangmu Village, Chuanshan Township) covers an area of 2,762 square kilometers, with an average width of 39.2 kilometers and the length of the main stream 105 kilometers. The shape of the basin is a long multi-branch water system with narrow top and wide bottom. Darongjiang to Guilin is a karst peak forest plain with a riverbed gradient of 0.94‰ and an average riverbed gradient of 0.44‰ in urban areas. [ 1]

In Yangshuo County, it flows into the county from Yan Guan Village, Di Yang Township. Entering the county town, it flows through tributaries such as Di Yang, Xingping, Welfare, Yangshuo Town, Chengguan, Puyi, Nashanbei River, Tuling River, Dayuan River, Zhangguihe River, Shuangyue River, Tianjiahe River and Shuangqiao River. Ma Caoping entered Pingle County in Puyi Township, with a total length of 69 kilometers, accounting for the main stream of Lijiang River (usually called the section from Xing 'an to Pingle as Lijiang River, with a total length of 6544 kilometers). [5]

In Pingle County, the Lijiang River (Lipu River, Lijiang River and Chajiang River) meets in pingle town and is called Gui Jiang, which flows southward into Zhaoping County.

River bed characteristics

The ground elevation on both banks of Guilin section of Lijiang River is between154 ~132m, which belongs to the first-class terrace deposit. The upper part is silty clay with a general thickness of 2 ~ 4m, and the lower part is sandy egg layer with a maximum thickness of 20 ~ 30m. The width of the channel is between125 ~ 585m, and the height of the river bank is 3 ~ 5m. The riverbed is composed of sand and pebbles, and there are aquatic plants all year round. The riverbed and the beach alternate, and the beach is long and deep. The floodplain is mainly distributed near Dongjiaxiang, Xintou, jiefang bridge, Xiangshan, Lijiang Bridge, Baiguoshu Village, Wu Jiali, Wang Jiali, Zhemu Town and Xiaolongmen Village. In dry season, the water depth of the beach is generally less than 1m, and the length of the beach is generally 500 ~ 1000m, of which Wu Jia beach is the longest, reaching1970 m. Deep pools on the riverbed are mainly distributed near Baishitan, Sizhou Bay, Mulongdu, Fubo Mountain, nine niang Wharf, Xiangshan, Nanxi Mountain, Jingping Mountain, Huziyan, Longmen Village and Ma Jiafang. When the rivers reach the deep pools, the water depth is all over 6m, the deepest is Jinping Mountain Pool, with the water depth exceeding14m, followed by Nanxi Mountain and Ma Jiafang, with the water depth exceeding12m. [ 1]

The banks of Yangshuo section of Lijiang River are the most typical karst peak forest landforms in the world, and also the most beautiful reach in Guangxi. Lijiang River starts from Qian Jing Village near Yangshuo County, enters the canyon area and winds among the mountains. This valley is 400 meters deep. Lijiang River is not only deep in valley, but also steep in riverbed, with an average of four thousandths, forming many beaches, continents, canyons and Rocky Mountains. There are 38 beaches on the Lijiang River in the county. There are 29 floodplains and floodplains with different widths, covering an area of 2,397 mu, with deep soil layer, soft texture, rich organic matter, moderate pH and high natural fertility. [5]

3 Hydrological characteristics

Huajiang, Chuanjiang, Yantian, Shandong and Gaozhai in the upper reaches of Lijiang River are one of the areas with high rainstorm value in China. The annual average precipitation in the central area is 2600 mm, the maximum precipitation in three hours is 27 1.9 mm, and the maximum precipitation in 24 hours is 425 mm, which is the main source of the Lijiang River flood. The average annual precipitation in Lingchuan Sanjie and Guilin is 1900 mm, and the precipitation in the basin decreases from northwest to southeast.

The surface runoff of Lijiang River comes from the surface water and groundwater in the basin, and the surface water seeps into the groundwater during the rain and flood. In dry season and dry season, groundwater supplies the river, forming the runoff process of Lijiang River. The measured annual average runoff at Guilin Hydrological Station of Lijiang River is 4.03 billion cubic meters (194 1 ~ 1990), with the measured maximum value of 5.63 billion cubic meters (1968) and the measured minimum value of 2.33 billion cubic meters (1963). The monthly distribution of runoff in a year is similar to that of precipitation in a basin. Among them, the runoff accounts for 77.5% in March-August, 37.7% in May-June, which is the high-value period of the whole year, and 4.5% in the following year from 65438+February to 65438+1October, which is the low-value period of runoff. The difference between high-value period and low-value period is 8.4 times. According to the actual measurement, the instantaneous maximum water level147.43m (1952), the maximum flow rate of 5200m3/s (1952) and the minimum water level140.18m (/kloc-0)

194 1 ~ 1990 Guilin's average runoff depth 1 120mm, annual runoff of 633 million cubic meters, inflow of 3.88 billion cubic meters, surface water resources of 4.5/kloc-0.00 billion cubic meters and per capita water consumption of 65438.

The sediment of Lijiang River mainly comes from the upper reaches of Xing 'an, Lingchuan and taohuajiang, which is formed by heavy rains and floods scouring the ground and banks, and is mainly suspended sediment. The change of sediment concentration depends on rainstorm and flood. The sediment concentration is high in flood season, and the measured maximum value of the section of Guilin Hydrological Station reaches 10.3kg/m3 (1977), while the sediment concentration is low in dry season. 1, February, 1 1 and 12 are often close to zero every year. The average sediment concentration for many years is 0.084 kg/m3, and the average sediment transport for many years is 343,000 tons. The upper reaches of Lijiang River flow through mountainous areas, with lush vegetation, high coverage and little topsoil loss. The riverbed below Simenkou is mainly composed of pebbles and sand, with a small amount of silt. At the same time, there are deep pools on its riverbed, which play the role of settling sediment and clarifying water color, creating a crystal clear river, becoming the river with the lowest sediment concentration in Guangxi and winning the reputation of "making the river a green belt". [ 1]

Specific to Yangshuo County, it has the following characteristics:

(a) the relative flow is abundant. According to the data of Yangshuo Hydrological Station, the annual maximum runoff modulus is 55.8 cubic decimeter per second square kilometer, with an average of 38.8 cubic decimeter per second square kilometer, which is second only to Liujiang River and higher than Hongshui River and Yujiang River. However, 1984 and 1985 are less than the multi-year average 10%. This is related to the serious destruction of vegetation in the basin.

(2) Summer rises and winter dries up, with ups and downs. According to the data from 1967 to 1985, the difference between the minimum discharge of Lijiang River in dry season and the maximum discharge in flood season is 5 14.6 times, which is the highest in Guangxi, while the difference between Nanliu River, which ranks second in Guangxi, is only 240 times. The maximum discharge in 1974 was 6330 m3/s, while the minimum discharge in the same year was only 13. 1 m3/s, and its appearance date was165438+1October 30th, earlier than other years. The minimum flow of 1972 is only 12.3 cubic meters per second.

The ups and downs are extremely unfavorable to the navigation of tourist ships all year round. According to the measured data of Yangshuo Hydrological Station, the highest water level of 1974 (above the Pearl River base) is11.75m, and the lowest water level is 102.64m, with a general difference of 8-9m. As a result, the guarantee rate of navigable water level (103.20m) is low and the number of days is few. The highest year (1982) is 304 days, and the lowest year (1974) is only 180 days.

This is because the Lijiang River basin has deep rivers, narrow channels and large river bed gradient. Every time we encounter heavy rain and mountain torrents, the river surges and the water level rises sharply. After the rainstorm, the river subsided and the water level dropped sharply. Especially in Guilin, there are many droughts in autumn and little rain in winter, which leads to the lowest water level and large water level difference. In addition, the destruction of vegetation in the basin is also very important. For example, Bangu Village, Baisha Town, located in the Lijiang River Basin, had a forest area of 1 1,000 mu in the 1950s, and clean water was everywhere. At present, among the hills in the village 132, 26 have shaved their heads, 83 have been cut into scorpions, and 23 are slightly better. The forest coverage rate dropped from 59.8% to 30%, and nearly 5,000 mu of forest was destroyed. Therefore, the function of forest water conservation is reduced, and streams are often cut off. In autumn and winter, people in some places will go to 1 Duoli to fetch water for dinner.

(3) The flood season is long. Due to the early arrival of southeast monsoon in summer and the influence of typhoon in autumn, the rainy season of Lijiang River is longer, and the flood season determined by regional hydrological station is from March 1 to September 1, which lasts for half a year.

(4) Less sediment concentration. 1967 ~ 1984, the average sediment concentration is 0. 13 1 kg/m3, and the annual sediment discharge is 1.72 million tons. 1969 The lowest average sediment concentration is only 0.053 kg/m3, and the annual sediment discharge is 522,000 tons. It is a relatively clear river in Guangxi. But after the 1970s, the sediment concentration was more than twice as high as that of 1969. The worst 197 1 year, as high as 0.24 1 kg per cubic meter, 1984, as high as 0. 15 kg per cubic meter. Mainly due to the destruction of vegetation in the basin and serious soil erosion. In addition, the waves formed by cruise ships in the past hit the coast and brought sediment. 1980, the green washing area is 980m, and 1987 is 37,206m long, of which 164 has a minimum width of 2m, a maximum width of 20m and an average width of 4m-6m. Bamboo forest 1856 plants (clumps) were washed away, and 2234 plants (clumps) were washed away, of which the largest bamboo forest earthwork volume was 50 cubic meters. In addition, 49 120 newly-built young forest was washed away.

Water quality: Yangshuo Liuduan 1980, all the indexes reach the first-class standard except dissolved oxygen and the number of Escherichia coli. The cadmium concentration in 198 1 rose to the second level, and other indicators were the same as those in 1980. 1982, dissolved oxygen and cadmium concentration all reached the first grade, and Escherichia coli was the second grade, so the water quality was greatly improved. 1983 is the same as 1982. 1984 coliforms rose to the third level, and the rest remained at the first level. However, at 1985, the dissolved oxygen rose to the second level, and the number of coliforms seriously exceeded the third level standard, and the rest were all first level. It can be seen that the water quality of Lijiang River has improved from 198 1 to 1983, 1984 and 1985, and the water quality has deteriorated again: the number of coliforms has increased sharply and the dissolved oxygen has decreased. This is due to the great impact of the upstream cut-off in Guilin. After 1983, the pollution degree of tributaries such as Jiang Xiaodong River, Liangfeng River, Ningyuan River and nanxi river became worse. In addition, the garbage and feces in the towns along the Yangtze River in Di Yang-Xingping-Yangshuo were not properly treated and washed into the river when it rained. With the rapid increase of tourist boats, the excrement and garbage on board are discharged into the river, and the suspended matter brought by the collision of tourist boats with the river bank. According to the monitoring of 1985, the dissolved oxygen in the section from Di Yang to Xingping is Class II, and Escherichia coli is Class III. On the section of Yangshuo Bridge, the number of coliforms is 3 to 6 times that of the third-class standard. In order to protect the water quality of the Lijiang River, the Guihuagou regulation project in Yangshuo Town was put into use on 1986, and the county sewage was discharged into the Lijiang River after being purified by the oxidation pond. In addition, garbage and feces collection equipment will be set up on tourist boats, which will be concentrated on landing and fixed-point treatment. 1986 the monitoring data of the section of Lijiang bridge in yangshuo in February show that the water quality of Lijiang river has improved: the average coliform group has reached the third-grade standard for several years, the annual dissolved oxygen has reached the first-grade standard, and other indicators have reached or exceeded the first-grade standard. According to the monitoring data of county sewage oxidation pond by county environmental protection monitoring station1April 1988, the annual average since 1986 shows that the removal rate of chemical oxygen consumption is 85%, that of biochemical oxygen consumption is 9 1%, that of total colonies is 58%, and that of Escherichia coli is over 60%. The dissolved oxygen in the effluent (i.e. into Lijiang River) reached 4.70-7.66 mg/L, and the removal rate of suspended solids was 67.2%. [5]

4 General situation of water conservancy

Lijiang River was once an important waterway connecting Lingnan and the Central Plains, and played an important role in national unity and economic and cultural exchanges. In the thirty-third year of Qin Shihuang (2 14 BC), Shilu, a state under Qin supervision, dug a canal in xing an to connect the Yangtze River and the Pearl River. From the beginning of the Yuan Dynasty to the 24th year of the Yuan Dynasty (1287), Tuohuan, the king of Zhennan, led his division to sign his toes and set up Yinjiangli County East. In the second year of Hongwu in Ming Dynasty (1369), there were three inspection departments in Lijiang County: Qian Qiu Gorge, Baishitan and Lutiancheng. After 1930s, the shipping position and function of Lijiang River were gradually replaced by roads and railways.

According to statistics, before liberation, there were 7 weir dams 176 bamboo waterwheels176 in Lingchuan section of Lijiang River, which irrigated 4078 mu of farmland. Now it is replaced by water storage, water diversion and water lifting projects. Lijiang River is rich in sand storage and is a high-quality building material, especially the sand in Sanjie River. [4]

Yangshuo County has five main ferries (Shuangquan, Xingping, Yangshuo, Welfare and Puyi) and four main docks (Di Yang, Xingping, Yangshuo and Fuan). [5]

5 Tourism development

The scenery of Lijiang River has the reputation of "green hills, beautiful waters, strange caves and beautiful stones". The 83km section of the Lijiang River from Guilin to Yangshuo is the essence of the Lijiang River and the beautiful scenery of "deep pools, dangerous beaches, flowing springs and waterfalls". It is a typical, rich and concentrated karst terrain area, which condenses the essence of Guilin's landscape and gives people the feeling of "sailing on the blue waves and people roaming in the picture world".

1982165438+10 "Guilin Lijiang scenic spot" was listed as the first batch of national key scenic spots in the State Council and needs special protection. 199 1 65438+February, Lijiang Scenic Area ranked second in the list of "Top 40 Tourist Attractions in China" published by the National Tourism Administration. 1996165438+10 The Lijiang River was listed as one of the 13 rivers under special state protection. 1April 1997, Guilin-Yangshuo route was rated as "Guangxi Waterway Transportation Civilized Route" by Guangxi Communications Department. 1May, 1998, Guilin-Yangshuo tourist route was awarded "Guangxi Waterway Transportation Civilized Route" by the autonomous region. 1July, 1998, was identified as the first batch of "national civilized scenic spots demonstration sites". 199865438+In February, the spiritual civilization construction committee of the autonomous region awarded the Guilin-Yangshuo route as "Guangxi civilized route". From June 5438 to February 2000, the Ministry of Communications awarded the Guilin-Yangshuo route a ministerial-level "civilized route"; Mopanshan Wharf was awarded as "first-class civilized passenger station" and Zhujiang Wharf as "third-class civilized passenger station". Lijiang Scenic Area was rated as "National AAAA Scenic Area" by the National Tourism Administration. 200 1, 1 The Lijiang River route, known as the "golden waterway", was rated as "ministerial civilized route" by the Waterway Passenger Transport Tourism Management Committee of China Transportation Enterprise Management Association. In April, 2002, the tourism management of Lijiang River, with Guilin Municipal Transportation Bureau as the main body, passed three international management system certifications: ISO900 1 international quality management system, ISO1400/environmental protection management system and OHSASI800 1 occupational health and safety.