三峡库区山地灾害基本特征及滑坡与降水关系

连阴雨是滑坡、崩塌等地质灾害的重要诱发因素，也是三峡水库安全的潜在威胁。利用三峡库区39个站1960—2015年春季逐日降水观测资料，分别分析了总的连阴雨和各类连阴雨的时空分布特征和变化趋势。结果表明：（1）从空间上看，连阴雨过程频次、总天数和总降水量均呈现自北向南逐渐增多的分布特征；从时间上看，在近56 a连阴雨过程的频次、总天数和总降水量呈明显减少趋势，1979年以来过程降水强度显著增强且年际变率明显。（2）从分类来看，持续时间5~6 d的短期过程频次、总天数以及总降水量均呈弱增加趋势，降水强度在整个库区均较强，持续时间7~10 d的中期过程和持续时间10 d以上的长期过程频次、总天数和总降水量呈减少趋势，且长期过程的减少趋势更明显，在2000年以后很少出现。
（3）从连阴雨过程总降水量对春季总降水量的贡献占比趋势来看，连阴雨的贡献减弱，而小于5 d的非连阴雨过程增多。（4）就不同类型连阴雨而言，库区以南的区域主要以长期过程为主，而以北的地区主要以短、中期过程为主。（5）连阴雨过程总降水量的变化主要由过程总天数的变化引起。值得关注的是，在连阴雨长时间减少的背景下，在最近10 a来却表现出一些新的特征，连阴雨过程发生频次、总天数和总降水量增多且年际变率增大，特别在三峡库区的东南部，应重点关注库区东南部地质灾害。

Reconstructing recent landslide activity in relation to rainfall in the Llobregat River basin,Eastern Pyrenees,Spain

The consecutive rainfall event (CRE) is an important trigger to geologic hazards like landslide and collapse, which are potential risk factors for the safety of the Three Gorges Reservoir. Based on the daily precipitation dataset from 1960 to 2015, the spatial-temporal distribution and the trend of the CREs occurring in the Three Gorges Reservoir Area in spring are investigated. The results show that:(1) the occurrence frequency and duration days of the CREs exhibit regional differences, with a greater occurrence frequency and a longer duration for the CREs in the southern than those in the northern regions. The occurrence frequency and the duration of CREs as well as the precipitation have exhibited a trend of decrease in recent 56 years. The precipitation intensity slightly enhanced and the interannual variability of CREs is evident. (2) The CREs are classified into three categories, i.e., the short-termed done with the duration of 5 to 6 days, the medium-termed with the duration of 7 to 10 days and the long-termed with the duration of 11 days and beyond, and the spatial-temporal distribution and the trend of these CRE sub-categories are further compared.
The results suggest that the occurrence frequency, duration and precipitation of the short-termed CREs have increased slightly. In comparison, these feature variables in the medium-termed and the long-termed have decreased, particularly for the latter, because none has occurred since year 2000. (3) The trend of the ratio of precipitation of CREs to the total precipitation in spring is analyzed and the results suggested a decrease trend. In addition, the ratio of the transient rainfall with the duration less than 5 days has increased. (4) Specially, the long-termed sub-category dominates the reduction trend in the southern region, whereas the short-termed and the medium-termed play a major role for the reduction in the northern region. (5) The event accumulated precipitation is determined by the duration. In spite of such a reduction trend of CREs, which have shown some new features in the last 10 years, such as the increase in the occurrence frequency, precipitation intensity and interannual variability of the CREs have been found evident, particularly in the southeastern region. This implies an increased risk of the geological hazards, and thus deserves more attentions.