Investigation report on topography and climate characteristics of Tangshan

2. 1.2 Topography Tangshan is high in the north and low in the south, which is the central plain of Beishan and Nanhai, with a total area of 13472km2. The landform is mainly formed by the strong uplift of the northern Mongolian Plateau and Yanshan Mountains since Cenozoic, and the strong decline of the southern plain and Bohai Sea, which shows a trapezoidal downward trend from north to south, and gradually forms the following six landform types: ① Low mountains and hills. Located in the north of Jingshan Highway, with a total area of 3,396.6 square kilometers, accounting for 23.74% of the city's total area. (2) Mountains and valleys. There are mainly three river valleys: Sahe-Luanhe River Valley, Qianxi Luotun Luanhe River Valley and Luanhe-Huanxiang River Valley. The total area is 400.6 square kilometers, accounting for 2.8% of the city's total area. ③ Intermountain basin. There are mainly seven river basins, namely Zunhua Chengguan, Ping 'an City, Qian 'an Chengguan, Xinji, Jianchangying, Yejituo and Hazel Town. Area 193 1.5 square kilometers, accounting for 13.5% of the city's area. ④ Foothill platform. Mainly two foothills, Feng Run and Kaiping. ***309. 1 km2, accounting for 2. 16% of the whole city. ⑤ piedmont plain. Including Yutian piedmont alluvial plain, Huanxiang River-Douhe piedmont alluvial plain, Luanhe River-Shahe piedmont alluvial plain, * * * 3,968.9 square kilometers, accounting for 27.74% of the city, with abundant groundwater, good water quality and fertile soil, which is the main agriculture in this city. ⑥ Low plain area. It mainly includes two low plains, Binhai and Wolong Valley, with a total area of 4,300.9 square kilometers, accounting for 30.06% of the city. There are many depressions and swamps, with heavy soil, shallow groundwater, high salt content and serious soil salinization. 2. 1.3 rivers and water systems There are more than 70 rivers in Tangshan, including Luanhe River, Douhe River, Huanxiang River and Shahe River. The main rivers in the territory are the main tributaries of Luanhe River system and the tributaries of Shahe River to the north of Zunhua in Ji-Yun He River Basin of North Sanhe River system. The basin area of these rivers outside China is 53,576.1km2, accounting for 95.0% of the total water area. The average annual inflow is 3.256 billion cubic meters. 2. 1.4 climate Tangshan city belongs to the continental climate zone of warm temperate zone and semi-humid monsoon. Winter is controlled by polar continental air mass, with cold climate and scarce rain and snow; In spring, due to the influence of continental air mass, there is not much precipitation, and because of the prevailing northerly or westerly winds, the evaporation increases, often forming dry weather; In summer, due to the northward shift of the Pacific subtropical high ridge, the warm and humid air flow from the southwest or southeast ocean surface is transported northward, which becomes the main precipitation season; In autumn, the southeast monsoon weakens, the polar continental air mass gradually strengthens, and autumn gradually turns into a crisp rainy season. There are seven kinds of weather systems that affect our city in summer, namely northeast depression, East Mongolia vortex, cold drop, west trough, lateral variation, Yellow River cyclone and typhoon. According to statistics, the main weather systems affecting our city are the West Trough and the cold drop. Our city is located on the north bank of Bohai Sea. When tropical cyclones, strong cold air and temperate cyclones pass through the sea area, the combination of strong wind and air pressure is easy to cause the accumulation of seawater on the windbank, and even make the water in the sea area react as a whole, forming a storm surge. The annual average temperature in the city is 10.6℃, the lowest in June, and the monthly average temperature is -5 ~-8℃, and the lowest can reach -26℃. The highest temperature is in July, the monthly average temperature is 25 ~ 26℃, and the highest temperature is 40℃. The average annual precipitation in the city is 644.2mm, of which the precipitation in flood season is 526.5mm, accounting for about 82% of the annual precipitation. The average frost-free period is 180 days, the first frost period is generally 65438+1early October, and the last frost period is early April of the following year. Good hydrothermal conditions, suitable for the growth of many crops such as wheat, corn, rice, peanuts and various dried and fresh fruits.

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