Rapid appraisal of rainfall threshold and selected landslides in Baguio, Philippines
Rapid appraisal of rainfall threshold and selected landslides in Baguio, Philippines
复制标题
菲律宾碧瑶降雨阈值和选定滑坡的快速评估
作者：
Dymphna Nolasco;L. Kumar;A. Tengonciang
菲律宾最容易发生山体滑坡的地区之一是碧瑶区，它是贸易、商业、教育和治理的中心。它也有全国最高的降雨量记录。降雨诱发的山体滑坡（RILs）每年发生，由西南季风、热带气旋及其相互作用引起的降雨引发;以及科迪勒拉山脉的地形抬升。自然和人为因素都是该地区易受RIL影响的原因。每次事故的死亡人数可达数百人，经济损失可达数十亿美元。2000年至2013年期间的降雨量和报告的RIL发生情况进行了汇编。主要的RIL，如2009年10月的台风芭玛煽动的特点和影响突出。大多数山体滑坡与热带气旋、增强的季风气流和24小时降雨量有关，降雨量从73毫米到1 086毫米不等，相当于每小时平均降雨量3毫米到45毫米。每日报告的山泥倾泻事件由1宗至41宗不等。据观察，滑坡、泥石流和泥石流是主要类型。由于观测到的引发山体滑坡的降雨量低于或在观测到的年最大24小时降雨量（164-1086毫米）的范围内，RIL可能会继续每年发生，并对碧瑶构成重大挑战。最低70毫米的日降雨量可以作为早期滑坡咨询的阈值。鉴于山泥倾泻的数目有限，以及就山泥倾泻的发生与其他控制/诱发因素的关系进行的分析，所确定的门槛只能被视为指示性的。
Among the most landslide prone in the Philippines is the Baguio district, a center of trade, commerce, education and governance. It also has the highest recorded rainfall in the country. Rainfall-induced landslides (RILs) occur yearly and are triggered by rainfall due to southwest monsoon, tropical cyclones and their interactions; and orographic lifting by the Cordillera mountain range. Both natural and human factors contribute to the region’s susceptibility to RIL. Fatalities can reach hundreds, and economic damages may reach billions of dollars per event. The rainfall and reported RIL occurrence were compiled for the period 2000–2013. The characteristics and impact of major RIL such as those instigated by Typhoon Parma in October 2009 are highlighted. Most landslides were associated with tropical cyclones, enhanced monsoon flow and 24-h rainfall that ranged from 73 to 1086 mm, corresponding to average rainfall rates of 3–45 mm per hour. The number of daily-reported landslide incidents ranged from 1 to 41. Slides, debris flows and earth flows were observed as the predominant types. As the observed landslide-triggering rainfall is below or within the range of the observed yearly maximum 24-h rainfall, which is 164–1086 mm, RIL will likely continue to occur annually and pose a major challenge for Baguio. The minimum of 70-mm daily rainfall may serve as a threshold for early landslide advisory. Given the limited number of landslides and analysis of landslide occurrence in relation to other controlling/predisposing factors undertaken, the threshold identified can only be regarded as indicative.