利用陕西省延安市12个气象站建站至2013年7月的降水资料和延安市降水引发的地质灾害资料，从1 h、3 h、6 h、12 h、日最大降水量、3 d连续最大降水量和月降水量等方面分析了延安市2013年7月连续降水的极端性和致灾特点。结果表明：延安市2013年7月全市平均降水量419 mm，为1000 a一遇极端降水。过程累积地质灾害次数(DL)和过程累计降水量(RL)关系密切，两者关系可以用分段函数描述。延安市RL＜137 mm时，无群发地质灾害；137mm≤RL＜200 mm且日降水量(RR)＜50 mm时，有群发地质灾害但较少；RL≥200 mm或200 mm＞RL≥137 mm且RR≥50 mm时，群发地质灾害多。经济比较发达、防灾减灾能力较强的延安市宝塔区2013年7月降水量568 mm，超过1000 a一遇，其RL＜332 mm时，无群发地质灾害；RL≥332 mm时，群发地质灾害多。%By using the precipitation data and geographic disasters data, in this study we analyzed the characteristics of extreme and disas-trous precipitation in Yan’an City during July 2013 from several angles including maximum precipitation during 1 h, 3 h, 6 h, 12 h and daily maximum precipitation, 3-day continuous maximum precipitation and monthly precipitation and so on. In the study we also analyzed the rela-tionship between process accumulated precipitation (RL) and process accumulated geological disaster frequency (DL), daily precipitation (RR) and daily geological disaster frequency (DR). The results show that:(1) The monthly mean precipitation in Yan'an city during July 2013 is 419 mm, which is a thousand year frequency extreme precipitation. (2) RL is closely related to DL, and the relationship between the two can be de-scribed by piecewise function. (3) There are no group geological disasters in Yan’an city when RL<137 mm, seldom when 200 mm>RL≥137 mm and RR<50 mm, and frequent when RL≥200 mm or 200 mm>RL≥137 mm and RR≥50 mm. (4) The precipitation of Baota district in Ju-ly 2013 is 568 mm, exceeding a 1 000-year frequency. There are no group geological disasters when RL<332 mm, and frequent group geolog-ical disasters when RL≥332 mm.
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