Geomorphic Effects of a Dammed Pleistocene Lake Formed by Landslides along the Upper Yellow River

Xiaohua Guo,Jiuchuan Wei,Zhaojun Song,Yudong Lu,Huimin Liu

doi:10.3390/w12051350

Xiaohua Guo, Jiuchuan Wei + Show 3 more

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https://doi.org/10.3390/w12051350

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Abstract

In a previous study two pairs of paleo-landslides within an 8 km reach of the upper Yellow River were studied and dated back to ca. 80 ka, however the relationship between these two pairs of paleo-landslides were not explored. This study inferred that the initial pair of landslides (Dehenglong and Suozi) appearing contiguously and forming an upstream 46 km-long lake along the river may be triggered by earthquake events from nearby capable faults. Subsequently, backwater inundating the valley floor as the dammed lake formed may cause shear stress of sediments lowered on steep slopes adjacent to the River, and eventually induce the other two additional landslides (Xiazangtan and Kangyang) ~8 km upstream. This could be inferred from two optically stimulated luminescence (OSL) samples yielding ca. 80 ka also, which were collected from asymmetric folds 10 to 30 cm in amplitude within the bedding plane between lake/lakeshore sediment and landslide mass at the front lobes of the two additional landslides. We estimated the maximum volume of this dammed lake was 38 km3 and may generate an outburst flood with an estimated peak discharge of 6.1 × 105 m3/s, which may cause massive geomorphic effects and potential disasters upstream and downstream. It is important to better understand the geomorphic process of this damming event in mountainous area with respect to reflecting tectonic uplift, paleoclimatic change and forecast and mitigate hazards on the northeast Tibetan Plateau.

Highlights

Dams formed by ice, moraines, or landslides in particular may be short lived and can give rise to large outburst flows following sudden failure, potentially resulting in substantial loss of life and damage to property [1,2,3]
optically stimulated luminescence (OSL) sample XZC-1 collected from lens of lakeshore deposits yielded an optical age of 89 ± 7 ka at the stratigraphic contact between Xiazangtan landslide and lakeshore sediments (Figure 5A) (Table 1), which is consistent with the ages of Xiazangtan landslide and the dammed lake formed by the Dehenglong–Suozi landslides.An OSL sample from silty sand of the asymmetric folds in a lacustrine section yielded an optical age of 84 ± 7 ka (WBJ-1) at the front lobe of Kangyang landslide (Figure 5B)
The asymmetric folds at the front lobe of Kanyang landslide were inferred to form because Kangyang landslide slid into the dammed lake that was inundated by Dehenglong–Suozi landslides, resulting in tsunami waves

Summary

Introduction

Dams formed by ice, moraines, or landslides in particular may be short lived and can give rise to large outburst flows following sudden failure, potentially resulting in substantial loss of life and damage to property [1,2,3]. This topic has received increasing attention in recent years, and systematically studying these naturally formed dammed lakes is of great importance to making mitigation strategies in the future [4,5,6,7,8,9]. Most of the dammed lakes along the upper stream of the Yellow River were not systematically studied, including a 46 km-long dammed

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