Neijiang, a county in the Eastern Han Dynasty, was once named Han 'an and Zhongjiang. The northern part of Tuojiang River is called Niu Shui, which is Beijiang River. The southern section is Zhijiang, called Nanjiang, and this is Zhongjiang. In the early Sui Dynasty, it was changed to Neijiang to avoid the taboo of Taizu Yang Zhongzhi. 195 1 year is set as Neijiang city. One said that because of the name of internal water (that is, Tuojiang River), cities and counties were built on the west bank of Tuojiang River. Here, the river winds into an arc, like a peninsula, hence the name of the city. Neijiang City (also known as Sweet City) is located in the southeast of the land of abundance, by the beautiful and rich Tuojiang River. Neijiang City is located at the east gate of Sichuan, connecting Chongqing in the east, Chengdu and Ziyang in the west, Zigong, Yibin and Luzhou in the south, Suining and Nanchong in the north, and chengdu-chongqing railway and neijiang-kunming railway in the north. Chengdu-Chongqing Expressway and Neiyi Expressway meet here. The highway density is higher than the national and provincial average, with a mileage of 3 149 km. It is an important intersection of traffic in southeastern Sichuan and even southwestern provinces. It is an important town in eastern Sichuan and one of the eight mega-cities with a population of one million planned and built in Sichuan Province. Geographical location: east longitude10415'-10526', north latitude 29 1 1 '-30 2'. The city covers an area of 5,386 square kilometers, and now has jurisdiction over three counties and two districts, namely, Shizhong District, Dongxing District, Weiyuan County, Zizhong County and Longchang County,11towns, 2,070 administrative villages,1sub-district offices and 253 community neighborhood committees. At the end of 2008, the total population was 4,250,500, including 840,000 non-agricultural population, 34 1.600 agricultural population and 0/.637 hectares of cultivated land, with a per capita cultivated land area of 0.0385 hectares. Neijiang lies in the middle of Sichuan Basin. It is adjacent to Longquan Mountain in the west and Huaying Mountain in Chongqing in the east. The terrain is gentle, with shallow hills and flat dams alternating with each other, extending north and south. Together with the hilly areas of Zigong, Luzhou, Yibin, Deyang, Suining and Nanchong, it forms the whole hilly area in the basin, with a length of 12 1.5 km from east to west and a width of 94.7 km from north to south. It is a typical landform in the hilly area of central Sichuan. The main landform area is 300-500m above sea level. In this landform area, the river network is underdeveloped and the soil is insufficient. Neijiang area is a shallow hill in Sichuan basin. Shallow hills evolved from red strata of Jurassic and Baixie, accounting for 88.8% of the total area, and the rest are low mountains. Longquan Mountain in the northwest and Jiugong Mountain in the southwest are the watershed between Minjiang River and Tuojiang River, and the main peak is 800- 1000m above sea level. There are also the remaining veins of Huaying Mountain in the southeast-Luoguan Mountain and Shengdeng Mountain. The Tuofu Valley in the eastern shallow hills consists of some ridged peaks, with a general height of 450-560 meters. The whole terrain is high in the northwest and low in the southeast. The highest point in the territory is Lion Rock in Longquan Mountain, with an altitude of 992.3 meters, and the lowest point is the Shiyang River exit in Baishui Township, Anyue, with an altitude of 248 meters. There are Lianmu Mountain and Baiyun Mountain in Neijiang. The city is rich in mineral resources. Energy minerals mainly include coal, natural gas and oil shale; Non-metallic and building material minerals include limestone, sandstone, shale, refractory clay, bauxite, marble, river sand, gravel and ceramic clay. Metal minerals and dispersed elements include iron, potassium and gold, and dispersed elements such as aluminum, gallium, rubidium and lithium in salt mines, sylvite mines and coal seams; Chemical minerals include salt minerals and potassium-bearing hydromica clay minerals. Neijiang City is located in the center of the basin, with simple geological structure and relatively stable crust. The exposed strata in this area are mainly influenced by three geological structures: Wei Zi Dome Anticline, Shengdeng Dome Anticline and Luoguanshan Anticline. The minerals in the city are mainly distributed in Weiyuan, Zizhong and Longchang counties in these three structural zones. Natural gas is mainly produced in Wei Zi dome anticline and Shengdeng dome anticline, with proven reserves exceeding 60 billion cubic meters. Placer gold deposits occur in Zizhong, Shizhong and Dongxing areas along the river bed of Tuojiang River. Mineral resources are mainly coal, natural gas and limestone, with a small amount of salt, potassium-bearing clay, refractory clay, lead soil and placer gold. In the future, the development of mineral resources is promising. Influenced by the basin and local natural environment, Neijiang city has the characteristics of mild climate, abundant rainfall, sufficient light and heat and long frost-free period. It is warm in winter and hot in summer, with moderate rainfall. The average temperature is 15℃-28℃, the monthly average temperature is 6℃-8℃, the July average temperature is 26℃-28℃, the highest temperature is 4 1℃, the lowest temperature is -5.4℃, and the active accumulated temperature is about 598℃. China is rich in heat resources, with an average annual total solar radiation of 89.6 kcal/cm2, annual total sunshine hours 1 100- 1300 hours and a frost-free period of 330 days. The number of frost days in the whole year is generally about 4-8 days, and the disastrous weather is mainly drought, alternating with drought and flood; Spring, summer, autumn and winter, low temperature, strong wind and heavy rain occur from time to time, and the rain is remarkable. The annual temperature is obviously dry in winter and dry in spring, while summer drought and summer drought also occur from time to time. The annual rainfall is below 1000 mm, mostly distributed in summer, accounting for about 60% of the annual rainfall. The high temperature period is basically the same as the rainy season, accounting for about 17% in spring and only 4% in winter.