Why is the riverbed of Lanzhou section of the Yellow River exposed?

February 20th, 20 17 From the winter of 20 16 to the middle of February 20th17, Gansu experienced the warmest winter in the past 60 years. Due to the high temperature, 83% of the regional average temperature exceeds the historical extreme value; 60% of the regional precipitation is less than 50%, while Lanzhou has no precipitation for more than 100 days. Due to the lack of sufficient precipitation in Lanzhou section of the Yellow River, a large area of stones in the depths of the riverbed are exposed.

According to the meteorological department of Gansu Province, cold air has little activity, weak intensity and high temperature. Due to the climatic characteristics of few days and long duration of precipitation, the relative humidity of air in most areas of Gansu Province is low, the air is dry, and the fire risk rating of forest and grassland is high. The picture shows the wetland growing with the Yellow River. As the water level of the Yellow River drops, only dry reeds remain.

Since the beginning of winter, the average precipitation days in Gansu are only 2.5 days, 5 days less than normal, which is the second time since 196 1. 65438+1Since the end of June, there has been no effective precipitation in some areas of Gansu, and there have been no precipitation days for more than 40 days in 20 counties of Jiuquan, Zhangye, Wuwei, Lanzhou and Baiyin, including 20 16 years1October 29 to 201February 7.