ABSTRACT

During the afternoon of 23 September 2018, a flash flood event occurred at Peribán de Ramos (Michoacán, Mexico). This event was triggered by 2-h precipitation of 58 mm, affecting at least 100 families, damaging 30 houses and killing 8 people. We present the first assessment of this event, for which we carried out stratigraphic descriptions, took sedimentological samples of the deposits and performed numerical simulations with the FLO-2D model to recreate the flow. Our results present a good fit with the flow heights, velocities, and the distribution of the flood zones observed in the field. We additionally performed a flood hazard assessment based on a rainfall frequency analysis for extreme events of 2-h duration at different return periods. Results show that even the 2-year event would reach flow depths >5 m and velocities exceeding 6.5 m/s, causing the overspill of Cutio river, affecting ~1500 inhabitants and avocado farming lands, causing a bigger impact on the population’s incomes and their way of life. We consider that these types of events could become more frequent and of major magnitude due to the change in land cover and land use, obstruction of natural drainages and changes in precipitation patterns in response to climate change.

摘要

2018 年 9 月 23 日下午，佩里班德拉莫斯（墨西哥米却肯州）发生山洪暴发。这次事件是由2小时58毫米的降水引发的，影响了至少100个家庭，损坏了30栋房屋，造成8人死亡。我们对这一事件进行了首次评估，为此我们进行了地层描述，采集了沉积物的沉积学样本，并使用 FLO-2D 模型进行了数值模拟以重建流动。我们的结果与现场观察到的水流高度、速度和洪泛区的分布非常吻合。我们还根据不同重现期持续 2 小时的极端事件的降雨频率分析进行了洪水灾害评估。结果表明，即使是 2 年的事件也会达到>5 m 的水流深度和超过 6.5 m/s 的速度，造成库蒂奥河泛滥，影响约1500名居民和鳄梨种植地，对居民收入和生活方式造成更大影响。我们认为，由于土地覆盖和土地利用的变化、自然排水系统的阻碍以及气候变化导致的降水模式的变化，这些类型的事件可能会变得更加频繁和严重。