滑坡频度-降雨量的分形关系

Fractal relation of landslide frequency and rainfall

降雨-滑坡关系是对降雨引发的滑坡进行预报的一个重要基础。本文根据中国浙江省1990～2003年期间有明确日期和坐标记录的1414个滑坡数据和基本覆盖浙江全部陆地区域的1257个雨量站记录的日降雨量数据,研究了滑坡频度-降雨关系。研究结果表明,降雨引发滑坡的频度与降雨量之间遵循分形的幂指数关系,并且在两个尺度的降雨量范围内具有不同的标度指数。按照幂指数关系拟合的两条滑坡累计频度-降雨关系线交点(拐点)处的降雨量(Rin)指出了引发75%左右滑坡的累计降雨阀值的上边界(以THCR表示)。对1d、4d、6d和11d这4个累计降雨时段的研究表明,引发75%左右滑坡的累计降雨阀值分别为205mm(1d)、273mm(4d)、294mm(6d)、315mm(11d)。

This paper studied the relationship between the landslide occurrences and the rainfall level based on 1414 landslides from field survey and daily rainfall data corresponding to the date of the landslide occurrence during 1990-2003 in Zhejiang Province,China.The results showed that the cumulative frequency of the landslide occurrence correlates well with the landslide-triggering rainfall and can be described using two power-law relations with different scaling exponents for two different ranges of the rainfall level.The rainfall level corresponding to the intersection point of two fitted correlation lines may be defined as the cumulative rainfall threshold（THCR） that defines the upper-bound rainfall thresholds for triggering shallow landslides;a large number of landslides may be induced when the amount of cumulative rainfall comes to the THCR value.For the cumulative rainfall in four time intervals considered（1,4,6 and 11 days）,the THCR for triggering about 75% of landslides in the study region is 205mm for 1 day,273mm for 4 days,294 mm for 6 days,and 315 mm for 11 days,respectively.