The reason for the low precipitation in Zhaotong

Zhaotong City is located in the slope terrace terrain transitioning from the Sichuan Basin to the Yunnan-Guizhou Plateau. The special terrain of the "One Belt and Three Platforms" facing the northeast brings difficulties to this study of hydrometeorological factors. In particular, the complex precipitation distribution makes the difference between the north and south of the multi-year average annual precipitation reach 3.8 times. The distribution of precipitation within the year is extremely uneven. The amount of precipitation in the flood season decreases from 91% of the annual precipitation in the south to 66% in the north. The terrain is high in the southeast and low in the northeast. The highest point is Yaoshan 4040m, and the lowest point is 270m in Shuifu County. The main mountains and rivers are arranged from south to north, and the water systems are radial, tilting from southwest to northeast, near the Sichuan-Yunnan border, and the elevation is from Sichuan The 500m of the basin rises to 1200m, forming a crescent-shaped transition zone. This special terrain lifts and horizontally expands the southward-moving precipitation weather system, creating a stable northern rainy belt. The northern end of Wulian Peak, the upper section of Baishui River and the source area of ​​Chishui River and Wujiang River in Zhenxiong and Weixin, with an elevation of 1200~2000m, is the largest step in this area.