• 研究报告 •

### 绿洲防护林缓减冰雹灾害的动力学机制

1. 1内蒙古磴口荒漠生态系统国家定位观测研究站/中国林业科学研究院沙漠林业实验中心， 内蒙古磴口 015200；2内蒙古磴口县气象局， 内蒙古磴口 015200）
• 出版日期:2019-09-10 发布日期:2019-09-10

### The kinetic mechanism of oasis shelter forest in mitigating hail disaster.

LIU Ming-hu1, ZHANG Jian-ping1, SU Zhi1, GAO Jun-liang1, ZHAO Ying-ming1, MA Ying-bin1, MAN Da2, LU Zhan-dong2, WANG Zhi-gang1*

1. (1National Research Station of Inner Mongolia Dengkou Desert Ecosystem/Experimental Center of Desert Forestry, Chinese Academy of Forestry, Dengkou 015200, Inner Mongolia, China; 2Weather Bureau of Dengkou County, Dengkou 015200, Inner Mongolia, China).
• Online:2019-09-10 Published:2019-09-10

Abstract: We conducted an onthespot investigation on the occurrence of hail disaster in Dengkou County, Inner Mongolia on June 13, 2016, to uncover the protection and kinetic mechanism of the desert oasis farmland shelterbelt system against hail disasters. We selected typical plots to survey yield and survival rate of crops inside and outside shelterbelt network after hail disaster. We estimated the variation of the horizontal speed of hail falling near the ground (H=0-40 m), based on the damage degree of the external wall of buildings in different height. We estimated the variation of the vertical speed of hail falling near the ground (H=0.5-50 m), based on the damage degree of the roof in dust level flux analyzer in different heights. The results showed that the survival rate of corn outside and inside the shelterbelt network plots were 24% and 87% respectively. The horizontal and vertical speed of hail decreased with decreasing height, which was consistent with the declining trend of wind speed profile and subsidence flow near the ground. The kinetic mechanism of mitigating hail disaster of shelter forest is that there is a strong kinetic effect of air which serves as a medium between the oasis shelter forest and the hail. The wind break belt is strongly resistant to the nearsurface airflow movement, which curbs the sinking and divergence of the hail airflow. After entering the low wind speed zone of the shelterbelt network, the hail blocks receive greater air resistance than those in the forestless zone, and the vertical and horizontal speed are significantly lower than that outside the shelterbelt network area, thus the ability of hail disaster is apparently reduced. Our results provide scientific basis for shelter forest construction and the assessment of their disaster reduction benefit.