Abstract: Based on the observational hail data from 64 weather stations from 1971 to 2010 and 1:50 000 digital elevation model (DEM) in Dalian, the topographical factors such as elevation, slope, aspect, relief amplitude and terrain incision depth which can be extracted from digital elevation model were selected as potential affecting factors, and the relationships between topographical factors and hail were analyzed using  methods of a digital terrain analysis and an irregular zonal statistics and so on. The results indicate that mean elevation, west-northwest aspect and terrain incision depth are the major factors affecting the distribution of hail. With the increase of elevation, the occurrence probability of hail increases. The west-northwest aspect and complex topography are favorable to the formation of hail, especially for the latter. Finally, a regression equation is established to simulate the relationship between the hail and topographical factors, and the distribution map of hails is simulated. It shows that the serious hail disaster occurs in the northern Wafangdian and Pulandian, while it is seldom in the coastal and southern regions.

Key words: Digital elevation model (DEM), Hail, Topographical factors, Geographic information system (GIS)