Journal ArticleDOI
Objective definition of rainfall intensity–duration thresholds for the initiation of post-fire debris flows in southern California
TLDR
In this article, an objective method to define the threshold intensities for post-fire debris-flow prediction is proposed. But, the objective method is limited to the number of correct predictions of debris flow occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors.Abstract:
Rainfall intensity–duration (ID) thresholds are commonly used to predict the temporal occurrence of debris flows and shallow landslides. Typically, thresholds are subjectively defined as the upper limit of peak rainstorm intensities that do not produce debris flows and landslides, or as the lower limit of peak rainstorm intensities that initiate debris flows and landslides. In addition, peak rainstorm intensities are often used to define thresholds, as data regarding the precise timing of debris flows and associated rainfall intensities are usually not available, and rainfall characteristics are often estimated from distant gauging locations. Here, we attempt to improve the performance of existing threshold-based predictions of post-fire debris-flow occurrence by utilizing data on the precise timing of debris flows relative to rainfall intensity, and develop an objective method to define the threshold intensities. We objectively defined the thresholds by maximizing the number of correct predictions of debris flow occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors. We identified that (1) there were statistically significant differences between peak storm and triggering intensities, (2) the objectively defined threshold model presents a better balance between predictive success, false alarms and failed alarms than previous subjectively defined thresholds, (3) thresholds based on measurements of rainfall intensity over shorter duration (≤60 min) are better predictors of post-fire debris-flow initiation than longer duration thresholds, and (4) the objectively defined thresholds were exceeded prior to the recorded time of debris flow at frequencies similar to or better than subjective thresholds. Our findings highlight the need to better constrain the timing and processes of initiation of landslides and debris flows for future threshold studies. In addition, the methods used to define rainfall thresholds in this study represent a computationally simple means of deriving critical values for other studies of nonlinear phenomena characterized by thresholds.read more
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Journal ArticleDOI
Current research issues related to post-wildfire runoff and erosion processes
TL;DR: In this article, the authors identify and quantify functional relations between metrics of fire effects and soil hydraulic properties that will better represent the dynamic and transient conditions after a wildfire and determine the interaction between burned landscapes and temporally and spatially variable meso-scale precipitation, which is often the primary driver of post-wildfire runoff and erosion processes.
Journal ArticleDOI
Earthquake-Induced Chains of Geologic Hazards: Patterns, Mechanisms, and Impacts
Xuanmei Fan,Gianvito Scaringi,Gianvito Scaringi,Oliver Korup,A. Joshua West,Cees J. van Westen,Hakan Tanyas,Niels Hovius,Tristram Hales,Randall W. Jibson,Kate E. Allstadt,Li Min Zhang,Stephen G. Evans,Chong Xu,Gen Li,Xiangjun Pei,Qiang Xu,Runqiu Huang +17 more
TL;DR: In this paper, the authors analyze how earthquakes trigger landslides and highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface, highlighting research gaps.
Book ChapterDOI
What is debris flow
TL;DR: There are two types of debris flows, known as Lahar and Jökulhlaup as discussed by the authors, which have to do with flows that are related to volcanic activity, such as melting of glacial ice due to volcanic activities, intense rainfall on loose pyroclastic material, or the outbursting of a lake that was previously dammed by pyroteclastic or glacial material.
Journal ArticleDOI
A review of the recent literature on rainfall thresholds for landslide occurrence
TL;DR: The most recent papers published in scientific journals are reviewed, highlighting significant advances and critical issues and the definition of standard procedures for the identification of rainfall events and for the objective definition of the thresholds.
Journal ArticleDOI
Hydrogeomorphic response to extreme rainfall in headwater systems: Flash floods and debris flows
TL;DR: In this paper, the authors provide a review on current European and international research on early warning systems for flash floods and debris flows, identifying: (a) the state of the art; (b) knowledge gaps; and (c) suggested research directions to advance warning capabilities for extreme hydrogeomorphic processes.
References
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Journal ArticleDOI
A physically based model for the topographic control on shallow landsliding
TL;DR: In this paper, a model for the topographic influence on shallow landslide initiation is developed by coupling digital terrain data with near-surface through flow and slope stability models, which predicts the degree of soil saturation in response to a steady state rainfall for topographic elements defined by the intersection of contours and flow tube boundaries.