What is the terrain like in Beijing?

The northwest is high and the southeast is low.

Beijing is located at the northwest end of North China Plain, with the east longitude115 20 ′ to17 30 ′ and the north latitude 39 28 ′ to 4105 ′. Located in the middle of Haihe River basin, about 150 km east of Bohai Sea.

The total area of the city is 1.64 million square kilometers, the mountainous area is 1.02 million square kilometers, accounting for 62% of the total area, and the plain area is 6,200 square kilometers, accounting for 38% of the total area. The terrain of Beijing is high in the northwest and low in the southeast. The western hills in the west belong to Taihang Mountain range; The northern and northeastern parts of Du Jun belong to the Yanshan Mountains. The highest mountain is Dongling Mountain in Mentougou District, western Beijing. The lowest land is the southeast border of Tongzhou District.

Rainfall characteristics in Beijing area

(1) The precipitation variability is large.

The distribution of precipitation in Beijing is uneven during the year and varies greatly between years. According to statistics, the average annual rainfall in Beijing is 585 mm, and the rainfall in flood season (June to September) accounts for about 85% of the annual rainfall. The precipitation in flood season is often concentrated in several heavy rains at the end of July and the beginning of August, which is very easy to form floods. However, in spring and winter, there is little precipitation and droughts often occur. Drought and flood alternate. The annual precipitation (or precipitation in flood season) varies greatly from year to year, for example, the precipitation of 1869 is 242mm, and that of 1959 is 1406mm, with a difference of 4.8 times.

(2) The intensity and frequency of rainstorm are high.

According to the statistics of rainstorm data since 1949, the rainstorm with 24-hour rainfall greater than or equal to 50 mm occurs five times a year on average, with the youngest two times and the most frequent 15 times.

Heavy rains are not only frequent, but also very intense. The maximum rainfall of 1 hour can reach 1 50mm, and it is very common that the rainfall of1hour exceeds100mm. In recent years, extreme rainstorms have occurred frequently in cities. According to statistics, since 2004, there have been 88 times when the rainfall per hour has exceeded 70mm.

(3) Uneven distribution of precipitation.

Rainstorm centers in Beijing are distributed along the windward belt in front of Yanshan Mountain and Xishan Mountain, and the annual precipitation is above 650 mm ~ 700 mm, among which jujube trees and Shuiman River are the places where heavy rains occur. Thus gradually reduced to about 500mm in front of the mountain and behind the mountain. The famous rainstorm in the history of Beijing area is different in central position, intensity and coverage of rain area. Serious floods often occur in the central area of rainstorm, while the marginal areas of rainy areas suffer from less rainfall, less disasters and even drought due to long-term non-rain. This fully shows that regional differences in precipitation lead to different regional distributions of flood and drought disasters.

What is the source of the above content? Baidu Encyclopedia-Beijing