中文摘要：

青藏高原腹地的雹灾形成与其它地区有一定的差别。根据三江源地区126个乡整理的近60a的雹灾数据，分析了青海南部高原雹灾的空间和时间变化规律，并通过对雹灾次数与海拔高程、地形起伏度、居民点密度的相关分析，结果表明：三江源地区雹灾的高发区域为东北部的兴海、同德、贵南等地及南部的称多、玉树、囊谦等2个地区，雹灾主要发生在5～9月份，在6、8月份形成明显的双峰性特点，地形起伏度、居民点密度与雹灾频次具有明显的正相关，海拔高程与雹灾频次呈负相关。雨带推移和生产方式不同是三江源地区雹灾产生空间分异的主要原因。

英文摘要：

Hail disaster is an important natural weather disaster with severe weather in a short time and difficult to forecast, because of complex causes, rapid generation process, small special-scale, and various forming causes in the different regions. The Tibetan Plateau is one of main distribution area of hail disasters in China; one of disaster centers with higher incidence is in the Three-river Headwaters region. Due to the special geographical condition in- side the Tibetan Plateau, the formation of hail disasters in Three-river Headwaters region has some differences from the other areas. Basecl on the official statistics, meteorological data and previous researches, a synthetic database was established of hail disasters in 126 townships of the Three-river Headwaters region during 1950-201 l, and the Arc- GIS analysis tools were used to analyze the spatial-temporal change of the hail disasters. Correlation analysis was performed among the hail disasters, elevation, precipitation, topographic relief and resident sites density. The conclusions were given as follows ： （ 1 ） the high-risk centers of hail disasters in the Three-river Headwaters Region include two areas. One is the northeast area with average hail frequency of 26 days a- including Qinghai county, Tongde county, and Guide county. The other one is the south area with average hail frequency of 18 days a-l, includ- ing Chenduo county, Yushu county, and Nangqian county. （2）The frequency of hail disasters increased in recent 60 yrs., form 3 days a-1 in 1950s to 15 days a-1 in 1990s. The hailstorms mainly happen between May and September, and reaching peaks in June and August. （3）The correlation analysis among hail disasters and other natural and social factors shows that the hail disasters of the Three-river Headwaters region have the close relations with altitude, relief of land surface and＇ human activities. The hailstorm frequency has positive correlations with relief degree of land surface and resident sites density, while has negative corre