The hydrological situation of Guangzhou in recent years
1) Geographical location and scope
Guangzhou is the capital of Guangdong Province and the political, economic, technological, educational and cultural center of Guangdong Province. Guangzhou City is located in the south of mainland China, in the south-central part of Guangdong Province, on the northern edge of the Pearl River Delta, close to the estuary of the lower reaches of the Pearl River Basin. Its range is 112 degrees 57 minutes to 114 degrees 3 minutes east longitude, and 22 degrees 26 minutes to 23 degrees 56 minutes north latitude. It connects Boluo and Longmen counties in Huizhou City to the east, Sanshui, Nanhai and Shunde Districts of Foshan City to the west, the urban area of Qingyuan City and Fogang County and Xinfeng County of Shaoguan City to the north, and Dongguan City and Zhongshan City to the south. It faces Hong Kong and Macau Special Administrative Regions across the sea.
Due to the numerous islands and dense waterways at the Pearl River Estuary, including Humen, Jiaomen, Hongqimen and other waterways leading to the sea, Guangzhou has become an excellent seaport for China's ocean shipping and an import and export port in the Pearl River Basin. Guangzhou is also the intersection point of the Beijing-Guangzhou, Guangzhou-Shenzhen, Guangzhou-Maoming and Guangzhou-Meizhou-Shantou railways and the civil aviation transportation center of South China. It has extremely close connections with all parts of the country. Therefore, Guangzhou is known as the "Southern Gate" of China.
(2) Land area and land resource characteristics
In 2005, the total area of Guangzhou was 7434.40 square kilometers. Among them, the area of 10 districts under the municipal jurisdiction is 3843.43 square kilometers, accounting for 51.7% of the city's total area; the area of 2 county-level cities is 3590.97 square kilometers, accounting for 48.3%.
The cultivated land area in Guangzhou is 130,100 hectares, and the forestry land area is 257,000 hectares. Guangzhou has diverse land types, wide suitability and complex terrain. The terrain decreases from north to south, with the highest peak being Tiantangding at the junction of Conghua City and Longmen County in the north, with an altitude of 1,210 meters; the northeast is a medium-low mountainous area; the middle is a hilly basin; and the south is a coastal alluvial plain, which is part of the Pearl River Delta. . Due to the interaction of various natural factors, various land types are formed. According to the vertical zone of the land, it can be divided into the following types: (1) Medium and low mountainous land. It is a mountainous area with an altitude of more than 400 to 500 meters, mainly distributed in the northeastern part of Guangzhou City. The general slope is above 20 to 25 degrees. The parent material of soil is mainly granite and sand shale. This type of land is an important water conservation forest base and is suitable for the development of ecological forests and hydropower. (2) Hilly land. It is a slope in a vertical zone below an altitude of 400 to 500 meters. It is mainly distributed between mountains, basins, valleys and plains. It is distributed in Zengcheng City, Conghua City, Huadu District and the eastern and northern parts of urban areas. The soil parent material is mainly composed of Made of sand shale, granite and metamorphic rock. This type of land can be used as a growth base for timber forests and economic forests. (3) Gangtai. It is a gentle slope or a low slope with a relative elevation of less than 80 meters and a slope of less than 15 degrees. It is mainly distributed in Zengcheng City, Conghua City and Baiyun and Huangpu Districts. It is also scattered in Panyu District, Huadu District and Tianhe District. It is a soil The parent material is mainly composed of accumulated laterite, red rock series and sand shale. This type of land can be developed and utilized as agricultural land and is also suitable for growing fruits, economic forests or pasture. (4) Alluvial plain. The main areas include the Pearl River Delta plain, the Liuxi River alluvial Guanghua Plain, and the alluvial and marine plains in the coastal areas of Panyu and Nansha. The soil is deep and the land is fertile. It is the main production base for grain, sugar cane, and vegetables in Guangzhou. (5) Tidal flat. Mainly distributed in the coastal areas of Nansha, Wanqingsha and Xinken Town in Nansha District.
(3) Climate characteristics
Guangzhou is located in the south subtropical zone, and its climate is a typical monsoon ocean climate in the south subtropical zone. Because it is backed by mountains and faces the sea, the maritime climate characteristics are particularly significant, with climate characteristics such as warm and rainy weather, sufficient light and heat, small temperature differences, long summers, and short frost periods. Because the water and heat are at the same time, it is extremely conducive to the growth of crops, but the threat of natural disasters is also greater. Disastrous weather such as typhoons, heavy rains, cold waves, lightning, and haze often have adverse effects on industrial and agricultural production, transportation, etc.
There are sufficient light and heat resources. In 2005, the annual sunshine hours in Guangzhou ranged from 1288.5 to 1780.0 hours, the annual average temperature ranged from 21.9℃ to 22.8℃, the annual extreme maximum temperature ranged from 38.6℃ to 39.3℃, and the annual extreme minimum temperature ranged from 0.0℃ ~2.3℃. This summer, all districts (county-level cities) experienced high temperatures and extremely hot weather. In winter, except for frost and ice in Conghua City and Zengcheng City, there was basically no cold damage in other areas.
There is abundant rainfall. In this year, the total precipitation in various districts in Guangzhou ranged from 1384.4 to 2278.3 mm. Except for Panyu District, which was 15.0% less than the previous average, the other districts were 5.0% to 18.8% more than the previous average. The total precipitation in Zengcheng City was 2278.3 mm, ranking first in the city. First place, 18.8% more than the average over the years. The rainfall in the rainy season (April to September) accounts for 80% to 83% of the whole year. Due to the influence of topography, precipitation is more in mountainous areas than in plains, and more in the north than in the south. The distribution of precipitation time this year is extremely uneven, with significantly more precipitation in each region from April to June. In June, floods occurred in Zengcheng City due to local heavy rains and water from upstream. At the same time, the rainy season coincides with strong light and high heat, resulting in a very high climate biological potential, reaching 77865-97950 kg/ha.
The monsoon climate is prominent. The alternation of winter and summer monsoons is a prominent feature of Guangzhou's monsoon climate. The northerly wind in winter is formed by the southward expansion of the polar continental cold air mass, making the weather drier and colder; the southerly wind in summer is formed by the northward expansion of the tropical ocean warm air mass, and the weather is often warm, hot and humid. The transition from summer monsoon to winter monsoon usually occurs in September each year, while the transition from winter monsoon to summer monsoon usually occurs in April each year.
(4) Water Source Characteristics
Guangzhou City is located in the southern water-rich area, with a well-developed river system, numerous large and small rivers (wells), a vast water area, and a rainwater collection area of 100 square meters. There are 21 rivers with a length of more than 100 kilometers, and there are 231 rivers in Laoba District, with a total length of about 913 kilometers. It not only constitutes the unique cultural characteristics of Lingnan Water Town, but also plays a prominent role in improving the urban landscape and maintaining the stability of the urban ecological environment.
The main feature of Guangzhou’s water resources is that there are relatively few local water resources and relatively abundant transit water resources. The city’s water area is 74,400 hectares, accounting for 10% of the city’s land area. The main rivers include the Beijiang River, the north trunk stream of the Dongjiang River, Zengjiang River, Liuxi River, Baini River, the Guangzhou Reach of the Pearl River, Shiqiao Waterway, Shawan Waterway, etc. Beijiang , the Dongjiang River flows through Guangzhou City and merges with the Pearl River into the sea. The local average total water resources is 7.979 billion cubic meters, including 7.881 billion cubic meters of surface water and 1.487 billion cubic meters of groundwater. In terms of local water resources, there are 1.0601 million cubic meters per square kilometer, and 1,139 cubic meters per capita, which is one-half of the country's per capita water resources. The amount of water resources for transit passengers is 188.615 billion cubic meters, which is 23 times the total local water resources. The passenger water resources are mainly concentrated in the southern Wanghe District and Zengcheng City. The passenger water resources diverted from the Xijiang and Beijiang Rivers into Guangzhou City amount to 159.15 billion cubic meters, and the passenger water resources diverted from the Dongjiang River into the north main stream of the Dongjiang River are 14.203 billion cubic meters. cubic meters, increasing the water inflow from the upper reaches of the river to 2.828 billion cubic meters. The southern river network area is in the tidal influence area, with large runoff and strong tidal effect. The three major entrances of the Pearl River, Humen, Jiaomen and Hongqili, enter the Lingding Ocean and exit the South China Sea in the south of Guangzhou City. The annual high tide volume is 271 billion cubic meters and the annual ebb tide volume is 408.8 billion cubic meters. The annual runoff of the three major entrances is 137.7 billion cubic meters. Compared with meters, the annual tide can bring a large amount of water, part of which is fresh water resources that can be utilized.
(5) Biological resources
The natural conditions of Guangzhou provide a good ecological environment for the habitat and reproduction of various organisms and the cultivation of crops. There are many kinds of organisms and they grow rapidly. The zonal vegetation is the south subtropical monsoon evergreen broad-leaved forest, but there are very few natural forests. The forests in the mountains and hills are all secondary forests and artificial forests.
Cultivation crops have the distinctive characteristics of transition from tropical to subtropical areas, and are one of the regions with the richest fruit tree resources in the country, including 3 categories: tropical, subtropical and temperate zones, 40 families, 77 genera, 132 species and varieties* There are more than 500 varieties, and it is the center of the origin and formation of lychees, oranges, longans, black (white) olives, etc. Vegetables are famous for their high quality and variety, with more than 400 varieties in 14 categories. Flowers include foliage plants, fresh cut flowers, potted flowers, bonsais, potted oranges, ornamental seedlings, industrial flowers, etc. There are more than 300 traditional varieties and new varieties introduced, developed and utilized in recent years. There are also many types of grain, cash crops, livestock, aquatic products and wild animals, and there are many famous and special varieties.
(6) Mineral Resources
The geological structure of Guangzhou City is quite complex and has good mineralization conditions. 46 types of minerals have been discovered in 794 mineral locations, of which 43 types have been subject to geological survey and 29 types have proven reserves. Among the minerals with proven reserves, there are 15 types of large-scale, medium-sized or above, and 111 mining areas. The main minerals include granite for construction, cement limestone, ceramic clay, potassium, albite, refractory clay, quartz sand, mirabilite, nepheline, orthoclase, marble, mineral water and underground hot water. Among them, granite for construction The reserves are 2.10816 million tons, the cement limestone reserves are 376.0497 million tons, and the ceramic soil reserves are 24.4953 million tons. There is a severe shortage of fuel minerals and metal minerals in the area, and they are all small and scattered.