Guyuan geographical environment

Guyuan is located in the warm and semi-arid climate zone of the Loess Plateau, which belongs to a typical continental climate. It has the characteristics of long and cold winter, changeable temperature in spring, short and cool summer, rapid temperature drop in autumn, large temperature difference between day and night, less precipitation in spring and early summer, more disastrous weather and great regional precipitation difference. The annual average sunshine hours are 25 18.2 hours, the annual average temperature is 6. 1℃, the annual average precipitation is 492.2mm, the annual evaporation is 1753.2mm, and the active accumulated temperature greater than 10℃ is 2000-2700℃, and the frost-free period is/.

The main meteorological disasters in Guyuan are drought, strong wind, dust, low temperature freezing injury, high temperature, local hail, heavy rain and lightning. In spring, strong winds and sand blowing frequently occur, and meteorological disasters such as drought and low temperature freezing injury occur one after another. There are more strong convective weather such as local hail in summer, less dry and warm precipitation in autumn, and the phenomenon of dry and warm in winter is very obvious. Guyuan city is located in North China stratum and Qilian stratum, bounded by Longshou-Liupanshan deep fault. The secondary unit of stratigraphic area in North China is the marginal area of Shaanxi-Gansu-Ningxia Basin, and parts of Pengyang County, Jingyuan County and Yuanzhou District are located in Pingliang area of this area. Most of the remaining areas are located in Liupanshan District of Hexi Corridor-Liupanshan District and Jingyuan-Xiji District of North Qilian District. The distribution characteristics of Pingliang community strata are as follows: Lower Proterozoic, Cambrian, Ordovician, Carboniferous to Jurassic are well developed, but because of the large area of loess, it is only scattered in residual mountains or valleys; The Lower Cretaceous is widely distributed and thick. The Cenozoic is well developed and spread all over Guyuan. The strata in Liupanshan residential area are extremely incomplete, lacking Paleozoic, Triassic, Jurassic, Upper Cretaceous and Paleocene. The lower Proterozoic distributed sporadically. Copper mineralization of clastic rocks and sandstone in rivers and lakes deposited in the early Cretaceous. The oldest stratum exposed in Jingyuan-Xiji community is the Lower Proterozoic, and the Paleozoic is only the Middle and Lower Devonian. Cenozoic is the most widely distributed, lacking Paleocene. Most areas are covered by Quaternary loess, which constitutes loess hills.

Due to different geological structures, different stages of development from animal husbandry to farming and animal husbandry to dry farming, and the influence of natural conditions, soil types are also different, but the main soils can be divided into three categories: (1) black loessial soil, accounting for 66.4% of the total area, distributed in vast areas outside the mountain, that is, semi-humid and semi-arid areas in climate. (2) Mountain soil. Distribution accounts for 33.6% of the total area, including mountain meadow soil, mountain brown soil and mountain gray cinnamon soil. They are distributed from top to bottom in high mountain areas such as Liupan Mountain and Moon Mountain.