Zunyi geographical environment

Zunyi City is located in the north of Guizhou Province. Located in the middle and upper reaches of the Yangtze River and an important area for comprehensive development of the economic zone in central Guizhou, it is the core area and main corridor of the corridor of Chengdu-Chongqing Economic Zone, the bridgehead, main position and pioneer area of cooperation between Guizhou and Chongqing, and it is an important transportation hub for southwest China to undertake north and south, connect east and west, and connect the river with the sea. Between east longitude10617' 22 "and north latitude 2713'15". The city is 247.5 kilometers long from east to west and 232.5 kilometers from north to south. It borders tongren city and Qiandongnan Autonomous Prefecture in the east, Qiannan Prefecture in the southeast, Guiyang, the provincial capital, Bijie City in the southwest, Sichuan Province in the west and Chongqing City in the north. The central city is 0/44km away from Guiyang, the provincial capital, and 239km away from Chongqing in the north. Zunyi covers an area of 30,762 square kilometers, accounting for 17.46% of the total area of Guizhou Province. Zunyi City is located in the slope zone of transition from Yunnan-Guizhou Plateau to Hunan hills and Sichuan basin, with large topographic relief and complex landform types. The altitude is generally 800 ~ 1300m, which is on the second step of the national terrain. The flat dam and valley basin in Zunyi City account for 6.57%, the hills account for 28.35% and the mountains account for 65.08%. The Dalou mountain range from southwest to northeast has become a natural barrier, which is the watershed of the north-south water system of the city. Zunyi city is obviously divided into two regions in landform: Shannan is one of the main parts of Guizhou Plateau, which is mainly composed of low Zhongshan hills and wide valley basins. The cultivated land is relatively concentrated and contiguous, and the land utilization rate is high. It is the main producing area of grain and oil crops.

From the edge of Wujiang River Valley to Dalou Mountain Range, we can clearly see three platforms: the lowest level is 1000 ~ 1200m, the middle level is 1300 ~ 1350m, and the highest level is1500 ~/kloc-. In the north of the mountain, Zhongshan Canyon is the main one, with high mountains and deep valleys, obvious vertical differences between mountains and scattered cultivated land. The southern area accounts for 37.6% of the total area of Zunyi City, and the northern area accounts for 62.4%. According to the genesis, the landform types of Zunyi City can be divided into three categories: erosion landform area, erosion structural landform area and erosion landform area. Among them, karst landforms are the most widely distributed, accounting for about 75% of Zunyi's land area. The lowest elevation of Zunyi City is at the confluence of Xishui River and Chishui River at the junction of Chishui City and Hejiang County, Sichuan Province, with an altitude of 22 1 meter. Niujiaozhai, the highest mountain in Qingba Nature Reserve of Baizhiba, Tongzi County, is the highest peak of Dalou Mountain at an altitude of 2,227 meters.

Dalou Mountain is the main skeleton of the city's topography. This mountain range starts from Bijie City in the west and extends to Sichuan Province in the northeast. It is not only the watershed between Wujiang River and Chishui River, but also the boundary mountain between Guizhou Plateau and Sichuan Basin. The road section running through the central part of this city is in an arc protruding to the southeast, with an altitude of1500 ~ 2000m and a relative height difference of more than 500m. The famous Loushan Pass is located on the main vein of Dalou Mountain, and Xiaojian Mountain stands on the east and west sides, which is magnificent. The ancients called this pass "Feng Wan inserted into the sky and connected with the first line", which is very dangerous and has always been a battleground for military strategists. The elevation of the mountain pass is 1226 meters, and the height difference between north and south is 400 meters. Sichuan-Guizhou national highway winds through the pass, while Sichuan-Guizhou railway and Chongzun expressway tunnel through the abdomen of Loushan. The rivers in Zunyi City are divided into Wujiang River, Chishui River and Qijiang River, all of which belong to the Yangtze River basin. There are 4 16 rivers with flowing water in Zunyi city, with a river network density of 0.3km/km2, a river length of 10km or a rainwater collection area of more than 20km2. Among them, there are two main streams (Wujiang River and Chishui River), both of which are beneficial to navigation. The inland river voyage is 44 1km, which goes straight to the Yangtze River. There are 60 first-class tributaries, 68 second-class tributaries 168, 3 third-class tributaries 149, 33 fourth-class tributaries and 4 fifth-class tributaries. The surface runoff (river) is 65.438+0.788 billion cubic meters, which is about 654.38+07% of that of Guizhou Province, and the water production per square kilometer is 580,000 cubic meters, which is about twice the national average.

There are 463 rivers * * * over 0/0 km from Mayor Zunyi/KLOC, all of which belong to the Yangtze River Basin, with the Daloushan Mountains as the watershed, and the north and south belong to Wujiang District and the mainstream area in the upper reaches of the Yangtze River. The main stream area in the upper reaches of the Yangtze River includes the main stream of Chishui River and its main tributaries, such as Niudushui River, Tongzi River and Xishui River, and Wujiang District includes Pianyan River, Xiangjiang River, Qing Yu River and Furong River. Annual average of rivers in Zunyi City. The groundwater runoff is 4.225 billion cubic meters, and the annual power generation of exploitable hydropower resources is 20.5 billion kWh, and the per capita possession is 1.85 times that of the whole country. Zunyi city is particularly affected by monsoon. Winter and spring seasons are mostly affected by cold waves or cold air in the northern hemisphere, and winter winds are generally northeast or easterly. When Zunyi is affected by the northeast monsoon, the clouds are thick and low, and the radiation of the cloud top cools down at night, which often produces night rain. If the southerly airflow meets the northerly airflow between Sichuan and Guizhou again, it will often form a Yangtze shear line at an altitude of 3300 meters, or a quasi-static front in the near-surface layer, and the rainy weather will be longer. In mid-April, the southwest monsoon moved northward, cloudy weather decreased, cloudy days increased, and the temperature increased significantly. Due to the low latitude and strong sunshine in Zunyi, the temperature may rise above 30℃ for three consecutive days.

Due to the northward summer monsoon (southwest airflow), the water vapor swept from the Bay of Bengal and the Indian Ocean increased greatly, and Zunyi entered the rainy season around April 16, with frequent moderate to heavy rains. From May to June, the summer monsoon moved to the Yangtze River basin and met with the northerly airflow, resulting in rainy weather in the Yangtze River basin. Zunyi City is located in the upper reaches of the Yangtze River, which also produces heavy rainfall and frequent rainy weather. The summer monsoon continues to strengthen, and the southwest airflow continues to push north. Zunyi city is controlled by the pure southwest monsoon, and the rainy weather begins to end, and it enters sunny, high temperature and dry weather with little rain. In mid-September, the summer monsoon gradually weakened and retreated southward, and the winter monsoon gradually strengthened southward, and Zunyi began to experience continuous autumn rain. In the future, when the winter wind basically controls Zunyi, it turns cloudy and gloomy.

Zunyi City is located in the low latitude, and the cold air from Siberia greatly weakens its degeneration, so the extreme minimum temperature in the coldest winter period of 65438+1October is only-7.1℃ (197765438+1October 30th), which is 0.2 higher than that in Zhijiang at the same latitude. Summer is often influenced by the southwest monsoon, and the extreme maximum temperature in the hottest period over the years is only 38.7℃ (1953 August 18), which is lower than the neighboring Chongqing's 40.4℃ 1.7℃. The annual average temperature in Zunyi 15. 1℃ is 0.6℃ higher than that in Kunming. Therefore, Zunyi City has no severe cold in winter, no intense heat in summer, abundant rainfall and pleasant climate.

Spring (March-May): It is warm and windy in spring, but sometimes it is cold; The seasonal average temperature is about 15.3℃, and the total precipitation is close to 300mm. In spring, the temperature warms up early and sunny days increase. Generally, it passes through the first day of ≥ 10℃ in early April, but the climate is extremely unstable, and there is often late spring cold from late March to early April. Due to the frequent intersection of cold and warm air, hail occurs in April and May, which will bring serious disasters in some years. The rainy season usually begins in the middle and late April.

Summer (June-August): rainy in early summer, dry in midsummer, hot but not cold; The seasonal average temperature is about 24.65438 0℃, and the total precipitation is 400~500mm. The extreme maximum temperature appeared in late July, reaching 37.4℃, but the high temperature weather of ≥35℃ was only 1 ~ 5 days. Summer is the season with the most rainfall in the whole year, especially in early summer and June, which is the time with the most rainfall in a year. Heavy precipitation weather occurred, and severe floods occurred in some years. From July to August in midsummer, it is often controlled by the western Pacific subtropical high, and there is often a summer drought.

Autumn (September ~165438+1October): the temperature drops suddenly in autumn, and the autumn wind drizzles; The seasonal average temperature is about 16. 1℃, and the total precipitation is 240 ~ 280 mm In autumn, due to the sharp weakening of summer monsoon and the south wind in winter, the rainfall is obviously reduced, the temperature is obviously reduced, and the number of rainy days is gradually increasing. Autumn wind appeared in early September, and from mid-September to mid-June of 10, rainy weather appeared in more than half of the years, and rainy years also affected the production of Sanqiu. The rainy season usually ends in the middle and late June of 10.

Winter (12 ~ February): There is no severe cold, little rain and occasional freezing in winter. The seasonal average temperature is about 5.5℃, the total precipitation is 60 ~ 70 mm, and the extreme minimum temperature appears in late June of 1, reaching -7. 1℃. In winter, due to the frequent cold air activities, the static front of Yunnan and Guizhou often forms, resulting in more rain and less sunshine in our city, which is the season with the least radiation throughout the year. The coldest period often occurs in 65438+ in the middle of winter 10 month, and it is often accompanied by freezing.