Overview of water conservancy in Qinjiang River

There is one large-scale Lingdong Reservoir in the basin, 12 small (I) reservoirs including Niupita, Tongyoutang, and Longtang, and small (II) reservoirs such as Huangmao and Datianpo Reservoirs. 37, as well as numerous small mountain pond reservoirs. These mountain pond reservoirs control a total rainwater collection area of ??221.5 square kilometers, accounting for 21.2% of the total area of ??the basin, and a total storage capacity of 230 million cubic meters, accounting for 24.3% of the annual runoff of the basin.

Lingdong Reservoir is located 13 kilometers east of the county, at 109°23′ east longitude and 22°28′ north latitude. The dam is located between Dazhangdong and Yuanyanshan Village in Fozi Town. Because the reservoir is in the east part of the county, it is named Lingdong Reservoir. The project was surveyed and designed in 1957, and construction started in October 1958. In 1961, the main project of the hub was basically completed. During the construction period, the maximum daily labor force reached 25,000. In 1961, the reservoir was trial-filled with water and exerted some irrigation benefits. In 1963, the main dam, water release culvert, spillway and other key projects were completed. With the completion of the irrigation area project, irrigation benefits increased year by year. In 1977, irrigation benefits reached 173,000 acres. During the construction of the reservoir hub project, Premier Zhou En of the State Council came to Guangdong for an inspection and asked about the construction status of the Lingdong Reservoir, and instructed the project construction to strengthen specific leadership, conscientiously carry out the project construction, ensure the safety of the project, and realize its benefits as soon as possible. The reservoir has a rainwater collection area of ??145 square kilometers, a total storage capacity of 179 million cubic meters, and an effective storage capacity of 79 million cubic meters. The designed irrigation area of ??the reservoir is 177,450 acres (including the benefits of the melon project in the irrigation area). There are 2 hydropower stations built behind the dam, with 5 installed capacity of 1,240 kilowatts. After the completion of the reservoir, the Lingdong Reservoir Management Bureau was established on December 31, 1963, with a staff of 80 people; at the same time, seven water conservancy management offices were established: Fozi, Xinwei, Sanhai, Tanwei, Nalong, Sanlong and Luwu.

Niupita Reservoir is a project of the south main channel of Lingdong Reservoir. It is located in Lixingpo Village, Xintang Village Committee, Fozi Town, 4 kilometers away from Foziwei, at 109°22′ east longitude and 22°24′ north latitude. The project was constructed in November 1958. The rainwater collection area is 11.45 square kilometers. The main dam is a homogeneous earth dam with a height of 35.9 meters and a crest length of 150 meters. The total storage capacity is 5.97 million cubic meters and the effective storage capacity is 3.73 million cubic meters. When the reservoir is at normal water storage level, 240 acres of farmland are submerged. The spillway is located at the right end of the dam. It is a gate-type wide-top weir with a width of 4.8 meters. The maximum flood discharge flow is 118.8 cubic meters per second. The water release culverts are divided into high culverts and low culverts. Culvert tube. The high culvert pipe is an H-shaped gate, the diameter of the culvert pipe is 0.65 meters, and the water discharge flow is 1 cubic meter per second. The entrance of the low culvert pipe is opened and closed by a cable-stayed plate. The diameter of the pipe body is 0.9 meters, and the water discharge flow is 2.36 cubic meters per second. The reservoir benefits are included in the Lingdong Reservoir Irrigation District, and the reservoir is under the unified management of the Lingdong Reservoir Management Bureau.

Tiendingshan Reservoir is located in Tiandingshan Village, East Bank Village Committee, Tanwei Town, hence the name Tiandingshan Reservoir. It is 5 kilometers away from Tanwei and located at 109°11′ East Longitude and 22°18 North Latitude. '. The project was constructed in September 1957. The dam body is a homogeneous earth dam with a height of 14.5 meters and a crest length of 220 meters. It collects rainwater and covers an area of ??4.5 square kilometers. The total storage capacity is 3.13 million cubic meters and the effective storage capacity is 2.208 million cubic meters. The spillway is located in a mountain col on the right side of the dam. It is a wide-top weir with a width of 20 meters. The bottom flow dissipates energy and the maximum discharge flow is 124 cubic meters per second. The water discharge culvert is located at the right end of the dam, and the water is discharged through a stepped inclined pipe. The culvert is a reinforced concrete round pipe with an inner diameter of 0.8 meters. The maximum discharge flow is 0.5 cubic meters per second. When the reservoir reaches the normal water storage level, 470 acres of cultivated land will be submerged. The reservoir is a construction project of the south main channel of Lingdong Reservoir and is managed by the Lingdong Reservoir Management Bureau. The benefits are included in the Lingdong Irrigation District.

Tongyoutang Reservoir is located in Tongyoutang Village, Chazi Village Committee, Nalong Town, hence the name Tongyoutang Reservoir. It is 7 kilometers away from Nalongwei and located at 09°07′ east longitude and 22°17′ north latitude. . The project was constructed in January 1956. The dam body is a homogeneous earth dam with a height of 20.5 meters, a crest length of 160 meters, and two auxiliary dams with a maximum length of 36.5 meters. It collects rainwater and covers an area of ??5.28 square kilometers, with a total storage capacity of 3.33 million cubic meters and an effective storage capacity of 2.296 million cubic meters. The spillway is located at a mountain depression on the right side of the main dam. It is an open wide-top weir with a width of 18 meters. The bottom flow dissipates energy and the maximum discharge flow is 93.7 cubic meters per second. The water discharge culvert is located at the left end of the main dam. It is a reinforced concrete round pipe with an inner diameter of 0.7 meters. The discharge culvert is a stepped inclined pipe with a maximum flow rate of 0.82 cubic meters per second. When the reservoir reaches normal water storage level, 110 acres of cultivated land will be submerged.

The reservoir is a fruiting project of the south main channel of Lingdong Reservoir. The benefits are included in the Lingdong Irrigation District and are under the unified management of the Lingdong Reservoir Management Bureau.

Longtang Reservoir is located in Liwutang Village, Dama Village Committee, Sanlong Town, 6 kilometers away from Sanlongwei, at 109°00′ east longitude and 22°20′ north latitude. The project was constructed in September 1957. The dam is a homogeneous earth dam with a height of 15 meters, a crest length of 115 meters, and two auxiliary dams with a total length of 146 meters. The rainwater collection area is 6.29 square kilometers. The total storage capacity is 5.66 million cubic meters, and the effective storage capacity is 4.06 million cubic meters. The spillway is located in a mountain col on the right side of the main dam. It is an open wide-top weir with a width of 25 meters and a maximum discharge flow of 75 cubic meters per second. The water discharge culvert is located at the left end of the main dam. It is a circular reinforced concrete pipe with an inner diameter of 0.7 meters. The water is discharged through a stepped inclined pipe with a maximum discharge flow of 0.25 cubic meters per second. When the reservoir reaches the normal water storage level, 1,350 acres of cultivated land will be submerged. The reservoir is a fruiting project of the North Main Canal of Lingdong Reservoir. The benefits are included in the Lingdong Irrigation District and are under the unified management of the Lingdong Reservoir Management Bureau.

Jingtang Reservoir is located behind Jingtang Village, Pingsha Village Office, Pingji Town. It is a tributary of the Shuiche River in the Pingji section of the Qinjiang River Basin, intercepting the river for 6.91 kilometers. The dam area has a rainwater collection area of ??9.44 square kilometers. It is a medium-sized reservoir mainly used for irrigation, power generation and breeding. The total storage capacity is 11.16 million cubic meters, the effective storage capacity is 7 million cubic meters, and the dead storage capacity is 200,000 cubic meters. The designed irrigation area is 18,000 acres, irrigating farmland in 13 village offices in two towns, Pingji and Qingtang. Construction started in January 1959, and the main dam, auxiliary dam, and water discharge pipe were basically completed the following year. The main dam is a homogeneous earth dam. The dam crest elevation is 58 meters, the wave wall elevation is 59 meters, the dam height is 24 meters, the dam crest length is 107 meters, the top width is 5.5 meters, the normal water level is 54 meters, the design flood level is 56.46 meters, the check flood level is 57.46 meters, and the water level is controlled during the flood season. 50 meters, and the dead water level is 42 meters. The original designed irrigation area of ??the reservoir was 18,000 acres. After the completion of the reservoir, small (I) type reservoirs such as Nala and Zhucaolu and small (II) type reservoirs such as Jiqutang, Lecailu and Nadaba were placed under the Jingtang Irrigation District. Under unified management, the total irrigated area is 21,750 acres. The total main canal in the irrigation area is 4 kilometers long, and the main canal is 7 kilometers long. There are 12 branch canals with a total length of 50.2 kilometers, and 14 aqueducts with a length of 346 meters. Bainiuling, the origin of the Qinjiang River, is the peak of the Dongshan Mountains, the remnant of the Liuwan Mountains. The Liuwan Mountains extend into the northeast of Lingshan County, and two mountain ranges, Luoyang Mountain and Dongshan Mountain, are formed in the county. The general direction of the mountains is northeast—— Southwest direction. Among them, the Dongshan Mountain Range starts from the north of Pingshan Town and stretches to the north of the Qinjiang River. It is the watershed between the Qianlu River, Xiuzhu River and Pingnan River of the Qinjiang River System and the Yujiang River System. The main peak is Dongshan, with an altitude of 714.9 meters. It is located between Pingshan and Fengtang towns. It is the largest mountain in the county.

The terrain of Lingshan County in the upper reaches is high in the northeast and low in the southwest. The northeast is a high hilly area (i.e., low mountains), the northwest is a medium hilly area, the middle is low hills and basins alternately, and the south is a low hilly area. In the high hilly areas in the northeast, the altitude is generally 200 to 800 meters; in the central Qinjiang Valley, the altitude is generally 30 to 100 meters; in the low hilly areas in the south, the altitude is generally 50 to 200 meters.

The middle and lower reaches are located in Qinzhou City. The northern part of the middle reaches is a low mountainous area. It is located in the north and northeast of Qinzhou City. There are four small mountain ranges, including Gudaoling, Jianling, Gaozhuoshan, and Hending, running from the northeast to It runs parallel to the southwest, thus dividing it into two belt-shaped alluvial plains along the Maoling River and south along the Qinjiang River, namely the Bandong Plain and the Pingji Jiubaidong Plain. The average altitude of small mountain ranges is between 400 and 630 meters. Gudaoling in the north is the highest, with an altitude of 629 meters, followed by Gaozhuoshan, with an altitude of 535 meters, which is a low mountain zone. The rocks are mostly granite, brown or green sandy shale.

The southern part of the middle reaches and the lower reaches are plains, and the northern part is alluvial plain, mainly distributed in the central and southern regions. The larger alluvial plains are Qinjiang Delta, Bandong Plain and Pingji Jiubaidong Plain. The Qinjiang Delta is located in the lower reaches of the Qinjiang River in the south of the city. It is formed by the alluvial flow of the Qinjiang River. It is the largest alluvial plain in the city and the second largest delta in Qinzhou area. Its top is a sandy slope in the northeast corner of the city. It develops in a bay between pincer-shaped hills. It is 10 kilometers long from north to south and 13-14 kilometers wide from east to west. It covers an area of ??135 square kilometers and has an average altitude of 3 meters. River sand and marine silt are staggered. , with obvious alternating phases of sea and land. The bay goes deep into the delta, with wide river channels, dense water networks, and good water, soil, light and heat conditions. It is an important grain and sugarcane producing area in Guangxi.

Jiubaidong Plain is located in the middle of Pingji Town. It is distributed in a strip along both sides of the Qinjiang River, covering an area of ??about 20 square kilometers. It is the second largest plain in Qinzhou City. The land in the plain area is fertile and rich in rice and sugar cane. It is one of the sugar cane bases in Qinzhou City. . The Bandong Plain is formed by the alluvial deposits of the Maoling River. It is distributed in a strip along both sides of the Maoling River in Bancheng and Xiaodong areas, covering an area of ??about 14 square kilometers. The parent material of the soil in the area is mostly granite, and the soil is the most fertile. It is the most fertile area in the city. The main grain-producing area is known as the "Qinzhou Granary". In addition, there are small alluvial plains among the low hills near Napeng in the southeast.

The lower reaches are coastal plains, mainly distributed in the southern coastal areas, with a relatively large area. Among them, Shabu, the southern part of Kangxi Ridge and Jianshan are the most broad and flat, while the southern part of Rhinoceros Foot is divided by rolling hills. Wave erosion has turned it into a coral zone. The soil parent material of the coastal plain in the city is mostly shallow sea sediments, and the soil is barren, mostly composed of highly acidic paddy soil, swampy saline soil and sandy soil, making it a low-yield food area in the city. Due to the influence of monsoons and topography, rainfall is extremely unevenly distributed throughout the year. The coastal plain has less rainfall in spring and is prone to drought, while it has more rainfall in summer and is prone to floods and tides.

The Qinjiang River finally flows into Maowei Sea, which is a small bay in Qinzhou Bay and is located in the northernmost part of the western sea of ??Qinzhou Bay. The bay has a wide mouth and a narrow mouth, and is oval in shape. It is surrounded by land on the east, west and north sides. It covers an area of ??about 135 square kilometers, most of which are dry beaches. The water in the sea is shallow, generally 0.1-5 meters deep. Injected by the Qinjiang River and the Maoling River, the river and the sea blend together, with low salinity, moderate temperature, and abundant plankton in the water. It is a good place for shallow-water fish and shellfish to breed. It is rich in oysters, perch, mullet, sea bream, yellow croaker, blue crab, etc., and is especially famous for its oysters. In the southeast and west of the bay are Qinzhou Marine Aquaculture Farm and Kangxiling Oyster Farm respectively, which are the city's offshore fishery production and marine aquaculture bases. In addition, there are lush sedge, aquatic plants and sea olive trees growing in the bay, and it is rich in wild waterfowl such as teal. Throughout the year, thousands of wild ducks, seagulls, sand snail doves and Demoiselle cranes live here.

The estuary forms a delta coast, which is characterized by the coast developing in the estuary bay; the branch channels are densely covered, the shoreline is cut and broken, and the tidal flat width is large, especially along the Maowei Sea, where the tidal flat area accounts for about 80% , the tidal flat is 5-7 kilometers wide, with a slope of <1‰; marine sand embankments are developed, and the coastline is significantly silted into the sea, which is conducive to land reclamation from the sea, and there are artificial embankments outside the shore. The upper reaches of the basin is in Lingshan County, which is located at low latitudes and has a south subtropical monsoon climate. The climate is mild throughout the year, with long summers and short winters, abundant rainfall, and sufficient sunlight. There are intermittent cold wave invasions in winter and spring. According to the records of the county weather station from 1956 to 1984, the annual average temperature is 21.7℃, the extreme maximum temperature is 38.2℃ (August 15, 1957), and the extreme minimum temperature is -0.2℃ (January 15, 1963). The annual accumulated temperature is 7500-8100℃, the average frost-free period is 348 days, and the average annual number of frost days is only 2.5 days. The total annual sunshine hours range from 1,400 to 1,950 hours, with an average of 1,673 hours. The maximum annual precipitation was 2,438 mm (1961), the minimum was 1,005 mm (1963), and the average was 1,658 mm. Most of the precipitation occurred from April to September. During this period, the precipitation accounted for 80% of the whole year. The average annual precipitation The number of days is 161 days.

Qinzhou City is located south of the Tropic of Cancer, in the famous monsoon region of southeastern Asia, with strong solar radiation and obvious monsoon circulation. As it faces the Beibu Gulf to the south and the Shiwanda Mountains to the northwest, it is mainly affected by the oceanic climate and also by the continental air mass. The oceanic climate is obvious and it is one of the hot, humid and rainy places.