Abstract:
By using the precipitation data and geographic disasters data, in this study we analyzed the characteristics of extreme and disastrous 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 relationship 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 described 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 July 2013 is 568 mm, exceeding a 1 000-year frequency. There are no group geological disasters when
RL < 332 mm, and frequent group geological disasters when
RL≥332 mm.