Impact of Water Level Fluctuations on Landslide Deformation at Longyangxia Reservoir, Qinghai Province, China

Shufen Zhao,Jun Liu,Hongxue Zhang,Runqiang Zeng,Zonglin Zhang,Yi Zhang,Xingmin Meng,Xiangpei Meng,Hong Wang

doi:10.3390/rs14010212

Abstract

The construction of Longyangxia Reservoir has altered the hydrogeological conditions of its banks. Infiltration and erosion caused by the periodic rise and fall of the water level leads to collapse of the reservoir banks and local deformation of the landslide. Due to heterogeneous topographic characteristics across the region, water level also varies between different location. Previous research on the influence of fluctuations in reservoir water level on landslide deformation has focused on single-point monitoring of specific slopes, and single-point water level monitoring data have often been used instead of water level data for the entire reservoir region. In addition, integrated remote sensing methods have seldom been used for regional analysis. In this study, the freely-available Landsat8 OLI and Sentinel-2 data were used to extract the water level of Longyangxia Reservoir using the NDWI method, and Sentinel-1A data were used to obtain landslide deformation time series using SBAS-InSAR technology. Taking the Chana, Chaxi, and Mangla River Estuary landslides (each having different reservoir water level depths) as typical examples, the influence of changes in reservoir water level on the deformation of three wading landslides was analyzed. Our main conclusions are as follows: First, the change in water level is the primary external factor controlling the deformation velocity and trend of landslides in the Longyangxia Reservoir, with falling water levels having the greatest influence. Second, the displacement of the Longyangxia Reservoir landslides lags water level changes by 0 to 62 days. Finally, this study provides a new method applicable other areas without water level monitoring data.

Highlights

Introduction iationsThe upper reaches of the Yellow River Basin are located in the transition zone between the Qinghai–Tibet Plateau and Loess Plateau in China
SBAS-Interferometric synthetic aperture radar (InSAR) technology was used to obtain the displacement rate of Longyangxia reservoir between 1 March 2017 and 21 March 2020, along the direction of the radar line of sight (LOS)
Longyangxia Reservoir is located in a region with an arid climate, with sparse vegetation dominated by low grass and shrubs (Figure 8b), which enables

Summary

Introduction

The upper reaches of the Yellow River Basin are located in the transition zone between the Qinghai–Tibet Plateau and Loess Plateau in China. Strong incision by the Yellow River has created high and steep terrain on both banks, promoting the occurrence of landslides. References [2,3], investigated disaster points in the upper reaches of the Yellow River and found that there are a total of 205 large and small landslides in the area, including 15 giant landslides (volume greater than 100 million m3 ). The upper reaches of the Yellow River have abundant hydraulic resources and have been developed as an important hydropower corridor following construction projects by the Chinese government to promote regional economic development. Of the Yellow River, 12 cascade hydropower stations have been built on the main river, with

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Conclusion