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Geomorphology and Flooding
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Giovanni Barrocu, Saeid Eslamian
The term landslide dam identifies a natural obstruction of a river channel caused by slope movements. The blockage can be complete or only partial; in both cases, it may form an impoundment and flooding upstream. Landslide-dammed lakes can remain stable, but such dams are frequently breached by overtopping, piping, or slope failure (Costa, 1991; Costa and Schuster, 1988). The breaching of a landslide dam can be a catastrophic event since it originates the formation and propagation of an anomalous flood wave downstream.
The 2014 Ludian co-seismic landslide dam (Yunnan, China): Transformation from high hazard to dual purpose water conservancy and hydropower project
Published in Jean-Pierre Tournier, Tony Bennett, Johanne Bibeau, Sustainable and Safe Dams Around the World, 2019
S.G. Evans, Jing Luo, Xiangjun Pei, Runqiu Huang
However, the breach of a landslide dam usually results in catastrophic flooding downstream, causing loss of life and property damage (Evans et al., 2011). It has been claimed that at least 5,500 deaths have occurred due to landslide dam failure events in China since 1900 (Chanson 2005; Dai et al. 2005). The Yigong landslide dam in Bomi County, Tibet, failed on 10 June 2000, 62 days after emplacement, when the debris dam breached following overtopping through an excavated spillway; the breach generated a major outburst flood downstream in the Yarlung Zangpo, Dihang, and Brahmaputra rivers, resulting in 30 deaths and 100 missing persons (Delaney & Evans 2015; Shang et al. 2003).
Criteria for a preliminary assessment of landslide dams evolution
Published in Jan Rybář, Josef Stemberk, Peter Wagner, Landslides, 2018
Areas located downstream from the dam are at higher risk (Casagli & Ermini, 1999), because of the possibility of a sudden dam failure; however also people living in the areas placed upstream are subjected to high hazard levels, as it is testified by several episodes inventoried in the Northern Apennine (Casagli & Ermini, 1999). For example, in 1812 a landslide occurred at Quarto sul Savio (Forlì, Italy); it completely blocked the Savio river, causing the formation of a huge landslide dam (Bertoni, 1843; Casagli & Ermini, 2000). On this occasion 18 people died, most of them drowned in the lake that inundated the areas located upstream from landslide dam. In this case no casualties were recorded in the downstream area, because of the stability of this huge natural blockage that in 1923 was selected as the site for the construction of an artificial concrete dam.
Increase in hazard from successive landslide-dammed lakes along the Jinsha River, Southwest China
Published in Geomatics, Natural Hazards and Risk, 2020
Hai-mei Liao, Xing-guo Yang, Hai-bo Li, Bin-Rui Gan, Jia-wen Zhou
The formation and collapse of landslide-dammed lakes are important geomorphic processes in sloped areas all over the world (Korup 2005; James and De Graff 2012; Hu et al. 2020a). A spontaneous breach of a landslide dam usually results in a sudden loss of damming materials and impounding water, posing threats to human lives and property and creating long-term impacts on the course of river channel (Fan et al. 2012; Huang and Fan 2013; Wu et al. 2016; Delaney and Evans 2017). Landslide-dammed lakes may occur successively at the same site, where a major landslide has been subjected to several reactivation phases chronologically that can supply enough materials to block the river channel (Zhou et al. 2013; Huang et al. 2016; Gan et al. 2020).
A geotechnical index for landslide dam stability assessment
Published in Geomatics, Natural Hazards and Risk, 2022
Hai-mei Liao, Xing-guo Yang, Gong-da Lu, Jian Tao, Jia-wen Zhou
Natural river-damming events induced by landslides have occurred in all mountain environments on the globe (Delaney and Evans 2015; Do et al. 2016). The potential outburst flood from landslide dam failure often poses a major hazard to society and environment downstream, making dam stability assessment necessary (Chen et al. 1992; Glancy and Bell 2000; Hewitt 2006; Davies and Korup 2007; Evans et al. 2011a, b; Hermanns et al. 2011a; Wu et al. 2016; Zhang et al. 2019; Jiang et al. 2021). Examples include the landslide dam formed on Dadu River China in 1786, which might have resulted in the largest number of casualties in the human history (≈1 × 105) (Dai et al. 2005). More recently, the Baige landslide dams impounding both the Jinsha River China in 2018 had caused evacuation of more than 1 × 105 people and extensive damage to infrastructure in the valley involved (Ministry of Emergency Management, PRC). Previous research and our investigations have indicated that there are also longer-lived dams which are preserved until today. Some of those dams provide opportunities for power generation and tourism (Weidinger et al. 2002; Duman 2009; Hermanns et al. 2009; Wang et al. 2012; Korup and Wang 2015; Delgado et al. 2020; Zhang et al. 2021). Examples include the Waikaremoana lake in New Zealand, which is a holiday destination and waterhead supply for a power station (Schuster and Alford 2004). And the 2014 Hongshiyan landslide dam in China that is also used for hydroelectricity generation after being stabilized by building concrete cut-off wall and headrace tunnel after emergency treatment (He et al. 2021). Thus, it is critical to increase our understanding of landslide dam stability assessment.
Quantitative monitoring method for analyzing the erosion of a landslide dam discharge channel using three-dimensional terrestrial laser scanning
Published in Geomatics, Natural Hazards and Risk, 2021
Nan Jiang, Hai-bo Li, Qing-jian Kou, Jia-wen Zhou
A landslide-dammed lake is typically a lake formed as a result of a landslide blocking the main river channel, which is often triggered by strong earthquakes or by heavy rainfall (Li et al. 2002; Hsu and Hsu 2009; Romeo et al. 2017). A landslide dam can be formed in a wide range of geological and geomorphological settings, such as debris flows, landslides, rock/debris slides and rockfalls (Fan et al. 2017). Korup (2002) studied 232 landslide dams in New Zealand, and found that 39% of them were triggered by earthquakes. The landslide dams usually consist of a mixture of rock and soil with uneven particle grading, low compactness and poor erosion resistance (Andrews 1983; Kundzewicz et al. 2019; Liao et al. 2020). Therefore, seepage and/or overtopping can occur on a landslide dam due to the loose composition, resulting in catastrophic floods around the downstream area and lead to considerable losses of property and life (Pickert et al. 2011; Liao et al. 2018; Chen et al. 2020). For example, the breakage of an earthquake-triggered landslide dammed-lake in 1786 on Dadu River, Southwest China, caused more than 100,000 casualties according to a historical recording (Dai et al. 2005). Therefore, it is necessary to carry out artificial interventions on landslide-dammed lakes to reduce their potential harm and risks (Kundzewicz et al. 2019). A widely used approach involves excavating the discharge channel at the top of a landslide dam. For loose landslide dams, drainage channels (artificially excavated or naturally formed) are usually eroded and expanded during the drainage process, leading to enhanced water flow in a short period of time that eventually form huge floods (Tuan et al. 2008; Xu et al. 2015a). Compared to the natural failure of a landslide dam, a discharge channel allows the dammed-lake to be released earlier, which significantly reduces the flood peak of the outburst flood during the dam failure and mitigates property damage downstream (Kundzewicz et al. 2019). The main factor controlling the peak flow of the outbreak flood is the rate of discharge channel expansion (Cao et al. 2004). The slowly expanding discharge channel can smooth the flow curves in hydrographs, delays the arrival of the flood and reduce its peak, thus providing sufficient time for flood control measures in downstream areas (Xu et al. 2015b; Chen et al. 2020). Therefore, it is of significant importance to study the erosion process of the discharge channel, which can provide a sufficient basis for regional disaster prevention and mitigation plans.