四川盆地泥石流、滑坡的时空分布特征及其气象成因分析

Analyses on Spatial-Timporal Characteristics of Mud-Rock Flow and Landslip in Sichuan Basin and Its Meteorological Cause

通过对1991—2001年四川盆地泥石流滑坡的时空分布特征与气象条件分析,得出了一些有益的认识,为泥石流滑坡预警预报提供了参考依据。(1)四川盆地泥石流滑坡主要发生在6～8月,以7月份为最多,多发区在四川盆地西南部,其次是四川盆地中、东部;岷江下游、沱江上中游是无泥石流滑坡区;在5～8月,有逐月从四川盆地东南部向西北推进到盆地西北部的趋势。(2)四川盆地泥石流、滑坡的气象成因是四川盆地多暴雨,为多发泥石流滑坡提供了充足的水源条件;四川盆地西北、西南部在大暴雨情况下,盆地西南、中东部在大雨、暴雨情况下发生泥石流滑坡的可能性大;在不同地质、地貌条件下,不同等级降水诱发泥石流滑坡的可能性还与前期的降水情况有关。反映了强降水对诱发泥石流滑坡的重要作用。

By analyzing the spatialtimporal charateristics of the mudrock flow and landslip in Sichuan basin during the period of 1999—2001 and its meteorological cause, the some useful results were obtained from it, which provided a reference for forcasting and warning landslip in advance. The results are as follows: (1) The spatialtemporal characteristics of the mudrock flow and lanslip in Sichuan basin are to mainly occurs in June～August, mostly in July; frequentlyoccurring areas of the mudrock flow and landslip located in southwesten Sichuan basin and then the middleeastern; no landslip occurs in the lower reach of Ming river and the middle and upper reaches of Tuo river, but there is a trend that the location of the landslip monthly moves from southwester to northwestern Sichuan basin in May～August. (2) So many landslip occurs in Sichuan basin is due to the meteorological reason, namely, the rain areas provide abundant water for it. (3) There is a great possibility with mudrock flow and landslip occurring if it is a sever heavy rain there, only a heavy rain or even just a rainfall with over 30 mm may trigger landslip in the southwester and middleeastern Sichuan basin. (4) Besides the mudrock flow and landslip related to the intensity of rain, geology and geomorphology, and it is also relevant with the precedingrainfall.