China
Africa
Explore chapters and articles related to this topic
A new debris flow mitigation method based on small watershed functional map: A case study in the Shenshui watershed, China
Published in Chongfu Huang, Zoe Nivolianitou, Risk Analysis Based on Data and Crisis Response Beyond Knowledge, 2019
Jun Wang, Qinghua Gong, Yan Yu*
Debris flows are rapid, gravity-induced mass movements consisting of a mixture of water, sediment, wood and anthropogenic debris that propagate along channels incised on mountain slopes and onto debris fans (Gregoretti et al. 2016). It has been reported in over 70 countries in the world and often causes severe economic losses and human casualties, seriously retarding social and economic development (Tecca and Genevois 2009; Degetto et al. 2015; Tiranti and Deangeli 2015; McCoy et al. 2012; Imaizumi et al. 2006; Hu et al. 2016; Cui et al. 2011; Dahal et al. 2009; Liu et al. 2010). Therefore, debris flow run-out effects analysis and mitigation are extremely important for preserving lives, mitigating disasters, and determining layouts for economic construction. Great efforts have been made to this issue (Stancanelli and Foti 2015; Berti and Simoni, 2007, 2014; Sakals et al. 2006; Viles et al. 2008; Armanini 2009; Tuladhar 2012; Wang et al. 2016; He and Zhai 2015; Li and Tuya 2015; Gao et al. 2016).
Geohazards
Published in White David, Cassidy Mark, Offshore Geotechnical Engineering, 2017
Slope failures initiate movement of material down-slope in the form of run-out, or mass gravity flows. Material involved in a slide originates as a solid material and gradually transforms towards a fluid state as it remoulds and softens during down-slope transport entraining additional water. Mass gravity flows following a submarine slope failure are generally described as debris flows and turbidity currents. The terminology of these phenomena is not standardised; Niedoroda et al. (2003) suggest the following distinctions. Debris flows are mass movements in which the source sediment travels downslope, coming to rest after the initially stored potential energy is dissipated by friction. During debris flows, the source sediment is remoulded and reconstituted, and the degree to which this occurs, including the amount of water entrained, determines the rheological and flow properties. The soil mass travels as a visco-plastic material with distinct stress–strain rate characteristics and flow is generally laminar. Turbidity currents are sediment rich heavy liquid flows that proceed from debris flows. Suspended sediment provides the density contrast with the ambient water in a turbulent current resulting in a gravitational energy that drives the flows. As turbidity currents travel downslope, they may pick up more sediment, becoming denser and accelerating, resulting in flow that is primarily turbulent. The density of a turbidity current is typically 2–4 per cent greater than the ambient water and speeds range from less than 1 m/s to more than 10 m/s.
Potential impacts of climate change on landslides occurrence in Canada
Published in Ken Ho, Suzanne Lacasse, Luciano Picarelli, Slope Safety Preparedness for Impact of Climate Change, 2017
C. Cloutier, J. Locat, M. Geertsema, M. Jakob, M. Schnorbus
Glaciers erode, redistribute and deposit sediments. Upon retreat and thinning, glaciers expose both scoured bedrock and glaciogenic sediment (Fig. 3.9). Exposed soils can range from thin veneers over bedrock to complex sediment assemblages tens of metres thick. The unvegetated, and often still ice-cored sediments in the alpine belt, are subject to a variety of hillslope processes (Ballantyne, 2002) and can be readily mobilized (Chiarle et al., 2007). Where unconsolidated and cohesionless sediments are exposed on steep slopes, debris flows are the primary agents of sediment transport (Ballantyne, 2002). Bulking of sediment in gullies and along channel side walls often result in long runout debris flows. While intense rainstorms and rapid snowmelt are the principal triggers of debris flows, sediment supply on relatively young steep slopes, and the lack of vegetative cover govern the magnitude (volume and peak discharge) of debris flows. This characteristic differentiates debris flows from recently deglaciated areas apart from other landslide prone regions worldwide (Geertsema and Chiarle, 2013). For example, in a survey of 19 alpine basins in southern B.C. Coast Mountains, Holm et al. (2004) found that debris movements were concentrated along Little Ice Age (LIA) lateral moraines and trimlines. Once mature vegetation invades these slopes, their stability increases in response to a changing hillslope hydrology (canopy intercept and evapotranspiration changes) and increasing root soil strength.
Bayesian learning of Gaussian mixture model for calculating debris flow exceedance probability
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2022
Qin-Xuan Deng, Jian He, Zi-Jun Cao, Iason Papaioannou, Dian-Qing Li, Kok-Kwang Phoon
Debris flow is a common geohazard in mountainous regions, threatening lives, properties and critical infrastructure. Predicting the occurrence and magnitude of debris flows is a challenging task due to its complex mechanism (Marchi and D’Agostino 2004; Eidsvig et al. 2014; Mostofi et al. 2019; Marin and Mattos 2020; Zhao, Lei, and Xu 2021; Xu, Yan, and Zhao 2021). Implementing debris flow mitigation strategies and/or countermeasures in practice requires reliable design references that can be derived from quantitative risk assessment of debris flows. For example, the risk level of a debris flow event can be quantitatively represented by the exceedance probability (EP) of some key kinetic and/or physical quantities. The EP is defined as the occurrence probability of these quantities exceeding certain threshold values assigned by practitioners.
Development of fragility curves for road embankments exposed to perpendicular debris flows
Published in Geomatics, Natural Hazards and Risk, 2021
Natalia Nieto, Alondra Chamorro, Tomás Echaveguren, Esteban Sáez, Alvaro González
Debris flows are sediment and water mixtures driven by gravity transporting debris of various sizes (Takahashi 2014; Jakob and Hungr 2005). This phenomena are considered the third most lethal and destructive natural hazard, after earthquakes and floods (Thouret et al. 2020). Prieto et al. (2018) emphasize that these phenomena represent a significant part of the global economic losses generated by hydrological hazards, often affecting human settlements and infrastructure located at valley bottoms. The consequences of debris flows include loss of human lifes, destruction of homes and facilities, damage to railway lines, destruction and interruption of roads, among other indirect consequences such as loss of productivity and social impact (Jakob and Hungr 2005; Tacnet et al. 2012). One of the most exposed infrastructures to these phenomena are road networks, as they adapt to the topographies in which they are located. In 2004 in Scotland a series of debris flows affected the road network, resulting in approximately US$2.5 million of direct costs for clearing, repairing, and replacing of damaged infrastructure (Winter et al. 2016). In 2006, an event affected the motorway connecting Sweden and Norway where losses of EUR$1.2 million were estimated due to road damage and disruption (Jenelius 2010). In 2015, several debris flows affected the North of Chile where damages to homes, buildings and road infrastructure were valued at US$1.5 billion (SERNAGEOMIN, Servicio Nacional de Geología y Minería 2017).
Reliability-based vulnerability analysis of bridge pier subjected to debris flow impact
Published in Structure and Infrastructure Engineering, 2022
Hao Tang, Chaoyi Xia, Kunpeng Wang, Jinghui Jiang, He Xia
Debris flow is a complex fluid-solid mixed flow, which is composed of viscous slurry with silt and clay (fine particles), and coarse boulders and debris boulders (coarse particles). The debris flow model established herein can be used to explore the impact action of fluid, solid, and fluid-solid coupling effect. The size of debris flow model is 12 m × 5 m × 6 m, in which arranged three solid particles with intervals of 2 m, as shown in Figure 4.