Talk about Beijiang River in the rain.

The Pearl River Delta is located in the south-central part of Guangdong Province, and consists of Xijiang River, Beijiang River, Dongjiang River, Gaoming River, Shapingshui River, Tanjiang River, Liuxi River, Shahe River, Suifu River, Zengjiang River, Yayao River, Nangang River, Maozhou River and Shenzhen River, which flow into the estuary alone. Generally, the Pearl River Delta is within the connecting lines of Xinhui, Heshan, Sanshui, Zengcheng, Dongguan and Shenzhen. It can be divided into Xijiang River Delta and Beijiang River Delta in the west (8370 square kilometers) and Dongjiang River Delta in the east (1380 square kilometers) with a total area of 9750 square kilometers.

The Pearl River Delta is a typical river network delta, with numerous water systems, numerous canals and criss-crossing tributaries. After reclamation, there are 65,438+005 main waterways in the river network area, with a length of 65,438+738 km. In addition, the density of the main tributary river network is 0.8 1-0.88km/km2, the river width is generally 300-500 m, the widest is about 2000m, and the ratio of width to depth is 65438+. However, due to the restriction of dikes, the riverbed is relatively stable, and it is divided into eight gates to go to sea. Judging from the mainstream drainage channels, they are basically independent systems.

The topography of the delta

The Pearl River Delta plain is low and flat, with an altitude of one o.2 to one o.9 meters. According to statistics, Shatian, with an altitude of 0.5-0.9 meters, covers an area of 3,560.4 square kilometers, accounting for 36.5% of the total area; The newly reclaimed coastal plain has an elevation of one o.2 to one o.3m and an area of1742.3km2, accounting for 17.9% of the total area. There are nearly 654.38 million fish ponds in Shunde, with an area of 1200 square kilometers, accounting for 12.3% of the total area. There are more than 160 hills, terraces and residual hills scattered on the plain, with an area of 1668.6 square kilometers, accounting for 17. 1% of the total area. The largest area is Wugui Mountain in the south, which is 530 meters above sea level and consists of Yanshanian granite. Strangely, Xiqiao Mountain in the west is 344 meters above sea level. It is the first extinct volcano in Himalaya and consists of Paleogene trachyte. There is also Lianhua Mountain in Panyu City, which is composed of Paleogene sandstone in the east. These hills are islands in the ancient bay before delta deposition. The average thickness of Quaternary in delta plain is 25. 1m, and the maximum thickness is 63.6m in Denglongsha. It is determined that the average deposition rate is 65438 0.6 mm per year. Delta margin and main channel are controlled by faults. Since the fifth year of the Northern Song Dynasty (1045), there have been 780 earthquakes in the delta and its surrounding areas, with high frequency but low magnitude. At present, the delta plain is still extending outward, and there are different degrees of siltation and beach reclamation outside the eight gates of the Pearl River. The annual sedimentation height of the beach downstream of Sikoumen in the east is 1.5-2.5cm, and the average sedimentation height of the western sea area in recent 20 years is 3.39cm ... Since the Qing Dynasty, the average elongation speed in the direction of Modaomen is 5.06 meters per year, and that in Dongjiang Delta is 8.2 meters.

The climate of the delta

The Pearl River Delta belongs to the south subtropical humid monsoon climate. The average temperature is 265438 0.8℃,165438 0.3℃ in October and 28.3-28.7℃ in July. The annual average precipitation is 1660- 1748 mm, with April-September as the flood season and10-March as the dry season. More than 80% precipitation is concentrated in the flood season. The average runoff depth for many years is 800- 1200mm, and the total annual flow of river network is about 320 billion cubic meters, which is six times that of the Yellow River. Due to the influence of monsoon and low geothermal level, it is often affected by floods, floods, tides, salt and drought. After liberation, a lot of water conservancy construction was carried out, which improved the disaster resistance.

Shipping in the delta

The Pearl River Delta, where rivers and seas meet, enjoys convenient transportation. There are 823 navigable waterways with a total length of 5,347 kilometers. By 1989, there were 90 large and small ports with annual throughput exceeding 1 10,000 tons, among which Guangzhou Port has become the largest international port with land-water combined transport and river-sea combined transport in South China, and has import and export business with 335 ports in 64 countries and regions around the world. In short, the Pearl River Delta has a mild and rainy climate, fertile land, rich products, dense population, developed culture and many overseas Chinese. It is the most developed area in Guangdong, and its urbanization level is among the best in the country. Now it has become a land of plenty and developed places, industry, agriculture, commerce, trade and tourism.