How well can we simulate complex hydro‐geomorphic process chains? The 2012 multi‐lake outburst flood in the Santa Cruz Valley (Cordillera Blanca, Perú)

Abstract

Changing high‐mountain environments are characterized by destabilizing ice, rock or debris slopes connected to evolving glacial lakes. Such configurations may lead to potentially devastating sequences of mass movements (process chains or cascades). Computer simulations are supposed to assist in anticipating the possible consequences of such phenomena in order to reduce the losses. The present study explores the potential of the novel computational tool r.avaflow for simulating complex process chains. r.avaflow employs an enhanced version of the Pudasaini (2012) general two‐phase mass flow model, allowing consideration of the interactions between solid and fluid components of the flow. We back‐calculate an event that occurred in 2012 when a landslide from a moraine slope triggered a multi‐lake outburst flood in the Artizón and Santa Cruz valleys, Cordillera Blanca, Peru, involving four lakes and a substantial amount of entrained debris along the path. The documented and reconstructed flow patterns are reproduced in a largely satisfactory way in the sense of empirical adequacy. However, small variations in the uncertain parameters can fundamentally influence the behaviour of the process chain through threshold effects and positive feedbacks. Forward simulations of possible future cascading events will rely on more comprehensive case and parameter studies, but particularly on the development of appropriate strategies for decision‐making based on uncertain simulation results. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

An Enhanced Framework to Quantify the Shape of Impulse Waves Using Asymmetry

“…The new condition describing the breaking wave limit (equation ) should be further investigated in order to determine the limitations in terms of scalability with field cases and applicability in three dimensions. This should also be evaluated for granular landslides that have interactions between solid and fluid components of the flow (e.g., Mergili et al, ) that impacts a water body.…”

“…When the release box is triggered, the gate swings open about a hinge at the top at a tip angular velocity of 1 ms. Water is used as the sliding material and impacts the reservoir as an idealized fast‐moving slide and thus is neutrally buoyant. With zero internal shear strength, this material is hypothesized to present an upper bound of slide mobility, representative of highly mobile slides such as a mudflow, water‐saturated debris flow, or liquefied soil that behaves as a fluid (e.g., Mergili et al, ). As the purpose of the work is to explore the evolution of a wide range of shapes of impulse waves during their postimpact travel time from the near‐field region, the findings are expected to be representative of postimpact wave evolution from other slide types that generate the same shape and amplitude of wave.…”

GLOFs in the WOS: bibliometrics, geographies and global trends of research on glacial lake outburst floods (Web of Science, 1979–2016)

“…Certain challenges are still seen ahead in this regard (e.g. Mergili et al, 2018;Westoby et al, 2014) despite rapid progress in this direction and improvements to technical capabilities as well as data availability and acquirability (e.g. Mallalieu et al, 2017;Wigmore and Mark, 2017).…”

A Multi‐Phase Mass Flow Model

“…This work should be seen as a first step in the direction of simulating real multi‐phase mass flows. Several important aspects can further be considered when simulating multi‐phase flows: Interaction processes are the key drivers to cause transitioning from one dynamic mass flow regime to another, eventually leading to a cascading mass flow event (Mergili, Emmer, et al, ; Mergili, Frank, et al, ). Interactions with the basal sliding surface and with water bodies are most relevant for rapid gravity‐driven mass flows.…”