general situation
Northeast Plain lies between Daxing 'anling, Xiaoxing 'anling and Changbai Mountain. It is about 1000 km long from north to south, 400 km wide from east to west and covers an area of 350,000 square kilometers. It is the largest plain in China. The Northeast Plain can be divided into three parts. The northeast is mainly the Sanjiang Plain alluvial by Heilongjiang, Songhua River and Wusuli River. The south is the Liaohe plain, which is mainly alluvial from the Liaohe River. In the middle, Songhuajiang River and Nenjiang River alluvial the Songnen Plain. The Great Plains of Northeast China is a plain surrounded by mountains and waters. After the founding of New China, a large number of demobilized soldiers, educated youth and cadres responded to the call of the state, and went to the "Great Northern Wilderness" with great aspirations to defend and build the frontier, draining swamps and reclaiming wasteland. Now it has developed into one of the major grain bases in China, and the inaccessible "Great Northern Wilderness" in the past has been built into a rich "Great Northern Warehouse".
location
Northeast Plain, the largest plain in China. Also known as Songliao Plain. Located in the northeast of China. Between 40 25' ~ 48 40' north latitude and118 40' ~128 east longitude. It is more than 0/000 kilometers long from north to south and 300-400 kilometers wide from east to west, with a total area of about 350,000 square kilometers. The eastern and western sides of the plain are Changbai Mountain and Daxing 'anling, the northern part is Xiaoxing 'anling, and the southern end is near Liaodong Bay.
natural resource
Land resources and oil resources are the most advantageous natural resources in the Northeast Plain. The plain soil layer is deep, fertile and rich in organic matter. Black soil with high natural fertility is dominant in the east and north, chernozem and meadow soil are dominant in the west, and meadow soil-tidal soil is distributed in Liaohe Plain in the south. Most areas of China are rich in surface water and groundwater, which are suitable for irrigation. According to statistics, the arable wasteland 1 10,000 mu, grassland 1 10,000 hectares and grassy slope 210.3 million hectares in China. The development potential of agriculture and animal husbandry is very huge. Oil is the most important mineral resource in the Northeast Plain. In the late Jurassic of Mesozoic, a depression basin was initially formed in the northern plain. During the development of Baijian River, the sedimentary thickness of lakes and rivers reached 6 meters. Later, due to the uplift and contraction of the basin, the Cenozoic sedimentary thickness was about 15(x) meters, which provided favorable conditions for oil generation. According to research, the total output of oil in Songliao Basin can reach 800 million tons. According to the accumulation coefficient of ro%, the total accumulation amount is about 8-10 million tons, and the prospect of natural gas reserves can reach more than 20 million cubic meters. In addition to Daqing Oilfield, there are Jilin Oilfield and Liaohe Oilfield. Liaohe Plain, where Liaohe Oilfield is located, is also a subsidence zone. Its downstream Cenozoic sedimentary thickness is more than 2 "ix "meters, which has a good oil-generating environment.
North China Plain
abstract
North China Plain is the second largest plain in China. Located in the lower reaches of the Yellow River. It starts from Taihang Mountain and Western Henan Mountain in the west, reaches the Yellow Sea, Bohai Sea and Shandong Hill in the east, starts from Yanshan Mountain in the north, reaches Tongbai Mountain and Dabie Mountain in the southwest, reaches northern Jiangsu and Anhui in the southeast, and is connected with the plain in the middle and lower reaches of the Yangtze River. It extends to Beijing, Tianjin, Hebei, Shandong, Henan, Anhui and Jiangsu provinces. The area is about 3 1 10,000 square kilometers. The North China Plain has a warm temperate monsoon climate with obvious changes in four seasons. The Huaihe river basin in the south is in a transitional area to the subtropical zone, and the temperature and precipitation are higher than those in the north. The average annual temperature in the plain is 8 ~ 15℃, and it is cold and dry in winter. Most crops are harvested three times a year and twice a year in the south.
localism
According to the different regional characteristics of the North China Plain, it can be divided into four sub-regional plains: the lower reaches of the Liaohe River, bounded by Shanhaiguan, and the outer plain of Shanhaiguan is alluvial from the Liaohe River, with more swamps, local salinization and low average temperature, but rice can still be planted in summer, and the main crops are sorghum, rice and corn; Haihe Plain, south of Yanshan Mountains, north of Yellow River and east of Taihang Mountain. It is alluvial from Haihe River and Yellow River, so it is also called Yellow Sea Plain, which is an important grain and cotton producing area in China, with a distance of more than 500 kilometers from north to south. The main crops of the so-called "Thousand Miles Plain" are wheat, corn and cotton. It can realize double cropping of wheat and corn in one year. The flood plain of the Yellow River is located between Haihe Plain and Huaibei Plain, which is alluvial by the Yellow River. There are many saline-alkali land and sandy land, but the average temperature is high, which is suitable for the growth of crops that like temperature and sand. The main crops are cotton, peanuts, rice and dates. Huaibei Plain, north of Huaihe River and south of Yellow River floodplain, is formed by Yellow River flood and Huaihe River flood, with high temperature and abundant water resources. Because of the flood of the Yellow River and the siltation of the Huaihe River trunk line in the past, famine often occurred in this area. After the Huaihe River was dredged, Huaibei Plain became one of the main wheat producing areas in China.
Plains of the Middle and Lower Reaches of the Yangtze River
abstract
In some places, the altitude is less than 5 meters, the river network is vertical and horizontal, and there are many lakes, so it is called "Water Town Zeguo". The banded plain in the middle and lower reaches east of the Three Gorges of the Yangtze River in China. From Wushan to the seaside in the east, Huaiyang Mountain in the north and Jiangnan hills in the south, it is alluvial by the Yangtze River and its tributaries. The area is about 6.5438+0.6 million square kilometers. The terrain is low and flat, and the ground height is mostly below 50 meters. In some places, the altitude is less than 5 meters, and there are many rivers and lakes, so it is known as "Water Town Zeguo". The middle reaches include Jianghan Plain in Hubei, Dongting Lake Plain in Hunan and Poyang Lake Plain in Jiangxi. The downstream plain includes the Yangtze River Delta along the Yangtze River in Anhui, Chaohu Plain and between Jiangsu, Zhejiang and Shanghai, in which the ground height of the Yangtze River Delta is below 10 meter. Rivers, branches and lakes are criss-crossed on the plain. Dongting Lake, Poyang Lake, Taihu Lake, gaoyou lake, Chaohu Lake, Hongze Lake and other famous freshwater lakes are all distributed in this narrow strip.
climate
Most of the climate belongs to the north subtropical zone, and a small part belongs to the northern edge of the middle subtropical zone. The annual average temperature is 14 ~ 18℃, the most Leng Yue average temperature is 0 ~ 5.5℃, the absolute minimum temperature is-10 ~-20℃, the hottest month average temperature is 27 ~ 28℃, and the frost-free period is 2 10 ~ 270 days. For agricultural crops, the annual precipitation is 1000 ~ 1400 mm, which is concentrated in spring and summer. Zonal soil is only found in low hills and gentle hills, mainly yellow brown soil or yellow cinnamon soil. The southern margin is red soil, and most of the plains are paddy soil. With developed agriculture and high land reclamation index (62. 1% in Shanghai and 45.6% in Jiangsu), it is an important grain, cotton and oil production base. Rich in rice, wheat, cotton, rape, silkworm, ramie, jute and so on.
Central Shaanxi plain
abstract
Guanzhong Plain, located in the middle of Shaanxi Province, is the richest place in Shaanxi Province, and it is also the place where China was first called "Huang Jincheng thousands of miles away, the land of abundance". History Last week, thirteen dynasties including Qin, Han, Sui and Tang established their capitals here, and Qin Zhou has been the capital of emperors since ancient times. "Huang Jincheng is thousands of miles away" means that the Guanzhong Plain is surrounded by mountains and rivers, just like a huge natural castle. There are Qinling Mountains in the south-central, Longshan Mountain in the west, Loess Plateau in the north, and Yellow River natural moats in the north and northwest. There is a natural terrain barrier in the east, which is easy to defend but difficult to attack. Since the Warring States period, there has been a saying of "a country with four blockades". Therefore, in the Han Dynasty, Sean used the advantage of "a golden city of thousands of miles" to persuade Liu Bang to make Guanzhong his capital. People are familiar with Sichuan Basin, which is customarily called "Land of Abundance", that is to say, it is rich in products, just like a land of abundance. In fact, Guan Zhong was the first to be called "Feng". During the Warring States Period, Su Qin told Qin Chen about the plan of "Lian Heng", praising Guanzhong's "fertile land, rich people, numerous chariots, tackling difficulties in all fields, fertile fields and abundant products", and said that "this so-called rich land is also a hero in the world", more than 500 years earlier than Chengdu Plain was awarded the title of "Land of Abundance". This is because Guanzhong has become a treasure trove of geomantic omen and the capital of emperors since Zheng Guoqu was restored in the Warring States Period.
cause
Guanzhong Plain connects Qinling Mountains in the south and Beishan Mountains in the north. Between the northern Shaanxi Plateau and the Qinling Mountains. From Baoji Gorge in the west to Tongguan Port in the east, it is about 360 kilometers long from east to west, narrow in the west and wide in the east. The total area is 39,064.5 square kilometers. Guanzhong plain is formed by river alluvial and loess accumulation, with flat terrain, fertile soil, rich water resources and good mechanical farming and irrigation conditions. It is the area with the best natural conditions in Shaanxi and is known as "Qinchuan in 800 Li". The Weihe River passes through the basin and flows into the Yellow River. The waterway is low and flat, with an altitude of 326-600 meters. From the Weihe River to the south, north and south, the terrain is asymmetrical and stepped, from the alluvial terrace of the first and second rivers to the first or second loess plateau 200 ~ 500 meters higher than the Weihe River. Terraces are distributed continuously on the north bank and incomplete on the south bank. The main tributaries of Weihe River also have corresponding multilevel terraces. The broad terrace plain is the most fertile area in Guanzhong. Between the second terrace on the north bank of Weihe River and the northern Shaanxi Plateau, there is a loess tableland in Weibei extending from east to west. The plateau is wide, with an altitude of 460 ~ 800 meters, and it is the main grain-producing area in Guanzhong. The loess tableland on the south side of Weihe River is intermittently distributed, about 250 ~ 400 meters higher than Weihe River, and it is stepped or inclined shield-shaped. It slopes gently from the northern foot of Qinling Mountains to Weihe Plain, such as Wuzhangyuan in Qishan, Shenheyuan, Shaolingyuan and Bailuyuan in the south of Xi, Yangguoyuan in Weinan, Gao Yuanyuan in Hua County and Yuyuan Garden in Huayin. At present, they have developed into a comprehensive agricultural area dominated by forests and gardens.