Zigong, a regional central city in southern Sichuan and the southern central city of Chengdu-Chongqing economic circle, enjoys the reputation of "Millennium Salt Capital", "Dinosaur Town", "Southern Lamp Capital" and "Gourmet House". The city governs Ziliujing, Gongjing, Daan, Yantan, Rongxian and Fushun counties, which are prefecture-level cities under the jurisdiction of Sichuan Province. 1990, Huidong New District (Zigong High-tech Industrial Development Zone) was established in Zigong, which is one of the four existing national high-tech zones in Sichuan Province. [ 1]

Zigong, one of the earliest 23 cities established in the Republic of China, is one of the richest cities in China and the city with the highest donation in War of Resistance against Japanese Aggression. Zigong is the earliest place to develop and utilize natural gas in the world, and the earliest provincial city and industrial center in Sichuan. During the Republic of China, Zigong was one of the most economically developed and densely populated areas in Sichuan. In the 20 13 ranking of China's urban competitiveness, Zigong ranks first among the top ten cities in the growth competitiveness of municipal administrative regions.

Zigong, the production base of high-quality commodity grain and pigs in China; It has many well-known domestic enterprises and national scientific research institutes, such as Chen Guang Research Institute, Carbon Black Industry Research Institute, Well, Mine and Salt Research Institute. Zigong is a national historical and cultural city, an excellent tourist city in China, a national garden city, an open city, a national intellectual property pilot city, a national health city, a national top 100 "city of literature", a provincial-level scenic spot and a provincial-level model city with beautiful environment.

Zigong's climate belongs to subtropical monsoon climate zone. The sunshine time is short, the four seasons are distinct and cloudy weather is common. The climate is warm, with annual average temperature 17.0- 18.0, extreme maximum temperature of 40, annual sunshine 1 150- 1200 hours. The frost-free period is 320-350 days. There is abundant rainfall, with an average annual precipitation of 1000- 1 100 mm.

It belongs to a typical basin climate with the characteristics of early spring, hot summer, cool autumn and warm winter. Zigong has a foggy climate and short sunshine time. The folk proverb "Shu dog barks at the sun" is an image description of this climate feature. The air in Zigong is very humid. Although the temperature is not high in summer, the average maximum temperature generally does not exceed 30 degrees Celsius, which often makes people feel sultry. The temperature is not low in winter, and the average monthly temperature is above 5 degrees Celsius. However, due to the influence of cloudy days and air tides, the rain in Zigong is concentrated in July and August, with a monthly rainfall of more than 200 mm and an average rainy day of 16- 18 days. In winter and spring, there is little rain and little snow and ice. [6]

topography

Zigong's shallow hills are undulating, and the terrain is inclined from northwest to southeast. Generally, the altitude is between 250 and 500 meters, and the urban area is between 280 and 400 meters. The rivers in the city are mainly the Tuojiang River system, and the lower reaches of the Tuojiang River flow through the city boundary 127 km. Fuxi River is the main tributary of Tuojiang River in the city, with Xushui River and Weiyuan River in the upper reaches, with a total basin area of 3,490 square kilometers. To the west of the city, Yuexi River runs through Rongxian County from north to south, belonging to Minjiang River system.

The tectonic system of Zigong is Yangzihuai, Sichuan Taiao, Zhongchuan Taigong and Zigong Depression. It is adjacent to Weiyuan-Longnvsi platform dome in the north, Chishui depression in the southeast, Luzhou uplift in the south and Liangshan fold belt in the southwest. The structure of this area is simple and the distribution of rocks is gentle. The southeast is tightly folded and has a long and narrow structure; The northwest structure is relatively broad and gentle. The terrain is high in the northwest and low in the southeast. The northwest is the distribution area of low mountains in the city, and the elevation of mountains is generally 500 ~ 800 meters. The highest point is the main peak of Dingjiashan in Rong county, with an altitude of 90 1 m. The elevation in the southeast is generally about 300-400 meters, mostly 300 meters (50 meters), and the lowest point is on the surface of Tuojiang River, with an altitude of 24 1 meter. The maximum relative height difference is 66 1m, and the general terrain relative height difference is less than 50m.

The landform type belongs to low mountains and hills, which are composed of low mountains, hills, flat dams and river valleys. The low mountains are banded, distributed in the northwest and southeast, with a wide distribution area, criss-crossing valleys and interspersed among hills. The terrain is dominated by hills, and the flat dams are very narrow and scattered, generally terraces along the river and flat land between hills. The terrain is divided into low mountains, hills and flat dams. The low mountains are mainly distributed in 13 towns in the west of Zheng 'an, Bao Hua and Lijia in Rong County, and in Shuanggu, Changshan, East of Liu Jia, and Qingshanling and Longguan Mountain in Fushun County, accounting for about 17% of the total area of the city, with hills accounting for about 80% and flat dams accounting for only 3% of the total area of the city. In addition, there are various valleys, accounting for nearly 45% of the city's total area, which are divided into gullies, gullies, erosion gullies, karst valleys, basins and river valleys. The density of all kinds of valleys is 2.85 kilometers per square kilometer. [2]

4 Natural resources

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land

Under the comprehensive action of specific climate, topography, parent material, biology and human beings, the soil in Zigong City has formed 5 soil types, 9 subtypes, 25 soil genera and 70 soil species. High yield soil accounts for 32%, middle yield soil accounts for 42%, low yield soil accounts for 26%, purple soil accounts for 50.08%, yellow loam soil accounts for 65,438+03.73%, and black cinnamon soil accounts for 0.765,438+0%. The total land area is large, with little arable land, which is divided into 5,443,600 mu of agricultural land; 765,300 mu of construction land; Other land is 349,800 mu. [4]

mineral

There are 18 proven minerals in Zigong, including salt mines and coal mines, and 12 exploited minerals, including rock salt, bituminous coal, limestone, brick shale, clay, kaolin and mineral water. The proven reserves of rock salt resources are 7.93 billion tons, coal resources are 64.8 million tons, and kaolin resources are 89 1 10,000 tons. In 20 10, the annual ore output was 10898400 tons, and the mining output value was 676 million yuan, accounting for 1.05438+0% of the total industrial output value of the city. [4]

water resource

The rivers in Zigong belong to Minjiang River and Tuojiang River. Yuexi River and Mangxi River in the west belong to Minjiang River system, with a drainage area of 1.207 square kilometers, and the rest belong to Tuojiang River system. Tuojiang River System There are Fuxi River, Xushui River, Weiyuan River, Changtan River, Zhenxi River and other important rivers in the city. There are 142 rivers with a drainage area of more than 5 square kilometers in the city, of which 17 rivers with a drainage area of more than 50 square kilometers are mostly feathered or tree-shaped. Zigong is extremely short of water resources, with a total water resource of about1600 million cubic meters, making it one of the 50 cities with the most serious water shortage in China. The city's per capita water resources are 585 cubic meters and 868 cubic meters per mu, which are only 18.84% and 23.5% of Sichuan Province's respectively. Especially in urban centers with dense population, concentrated factories and mines and prosperous commerce and trade, the problem of water shortage is particularly prominent. The per capita water resources is only 307 cubic meters, accounting for 9.7% of the per capita water resources in Sichuan Province.