Reconstruction of catastrophic outburst floods of the Diexi ancient landslide-dammed lake in the Upper Minjiang River, Eastern Tibetan Plateau

Abstract

Landslide-dammed lake outburst floods (LLOFs) may pose serious safety threats to nearby residents and their livelihoods, as well as cause major damages to the downstream areas in mountainous regions. This study presents the Diexi ancient landslide-dammed lake (DALL) in the Upper Minjiang River at the eastern margins of the Tibetan Plateau, which was known to an estimated previous maximal lake area of 1.1 × 10 7 m 2 and an impounded volume of 2.9 × 10 9 m 3 . Then, at approximately 27 ka BP, the ancient landslide dam failed and catastrophic LLOFs occurred. It was determined that the peak discharge of the Diexi ancient LLOFs could be reconstructed using regression, parametric, and boulder competence approaches. The reconstructed maximum peak discharge might be 72,232.66 m 3 /s, with an average velocity of 17.23 m/s, indicating that the Diexi ancient LLOFs were the most gigantic outburst floods to

Sedimentary records of giant landslide-dam breach events in western Sichuan, China

“…Therefore, new sedimentary evidence is needed to support these issues (Lord and Kehew, 1987;Cutler et al, 2002;Borgohain et al, 2020;Wang et al, 2023a). An abundance of ODs was discovered to be preserved in the Diexi Reach of the Upper Minjiang River and Tangjiashan Reach of the Tongkou River Basin (Ma et al, 2018;Jiang and Wei, 2020;Jiang et al, 2021;Ma et al, 2022). These ODs were formed by LLOFs induced by a giant ancient landslide-dammed lake and the Tangjiashan dammed lake, respectively, and they have good comparability in terms of deposition distribution, sedimentary characteristics and profile structures.…”

“…In recent years, an increasing number of studies on catastrophic flood events have been conducted in the Tibetan Plateau (Herget and Fontana, 2019;Baker et al, 2022;O'Connor et al, 2022;Yang et al, 2022). In most of the catastrophic flood cases, dammed lake OFs account for the largest number and widest distribution (Carling, 2013;Srivastava et al, 2017;Liu et al, 2019;Borgohain et al, 2020;Fan et al, 2020;Ma et al, 2022;Yang et al, 2022;Wang et al, 2023b).…”

“…Among these LLOFs, the high mountainous areas of the Tibetan Plateau in southwest China have the highest distribution. These LLOFs often have profound and lasting impacts on regional geomorphological evolution (Korup and Montgomery, 2008;Korup, 2012;Liu et al, 2018;Fan et al, 2020;Ma et al, 2022). Moreover, the outburst floods (OFs) will also cause a large influx of freshwater resources into the ocean, which is closely related to the fluctuations of the Quaternary climate (Teller et al, 2002).…”

“…For modern dammed lake OFs, there are usually historical or detailed data records, such as the 1933 Diexi Earthquake (25 August 1933, Ms.7.5), which resulted in 11 landslide-dammed lakes in the Diexi area, Sichuan, China, which breached on October 9 and killed approximately 2,500 people (Li et al, 1986). Another example is the Tangjiashan dammed lake induced by the Wenchuan Earthquake in 2008 (Cui et al, 2012;Peng and Zhang, 2013;Chen et al, 2015;Wang Z. et al, 2022) and the Baige dammed lake in Jinsha River in 2018 (Tian et al, 2020;Zhong et al, 2020;Liu et al, 2021;Zhang et al, 2023), both of which have detailed data on the OFs. However, there are no records of ancient OF events, particularly those that occurred during the geologic era, which need to be deduced using geomorphology, hydrology, sedimentology, meteorology, and other methods.…”

“…The OF sediments (outburst deposits, ODs) formed in the lower reaches of the dams are become the most direct evidence of OFs induced by dammed lakes. Analyzing the distribution and sedimentary characteristics of ODs is of great significance for the paleohydrological reconstruction of dammed lake OFs (Dai et al, 2005;Carling, 2013;Chen et al, 2013;Wang P. et al, 2014;Ma et al, 2022;Wang et al, 2023a;Wang et al, 2023b).…”