Multi-Sensor InSAR Assessment of Ground Deformations around Lake Mead and Its Relation to Water Level Changes

Mehdi Darvishi,Saeid Aminjafari,Georgia Destouni,Fernando Jaramillo

doi:10.3390/rs13030406

Abstract

Changes in subsurface water resources might alter the surrounding ground by generating subsidence or uplift, depending on geological and hydrogeological site characteristics. Improved understanding of the relationships between surface water storage and ground deformation is important for design and maintenance of hydraulic facilities and ground stability. Here, we construct one of the longest series of Interferometric Synthetic Aperture Radar (InSAR) to date, over twenty-five years, to study the relationships between water level changes and ground surface deformation in the surroundings of Lake Mead, United States, and at the site of the Hoover Dam. We use the Small Baseline Subset (SBAS) and Permanent scatterer interferometry (PSI) techniques over 177 SAR data, encompassing different SAR sensors including ERS1/2, Envisat, ALOS (PALSAR), and Sentinel-1(S1). We perform a cross-sensor examination of the relationship between water level changes and ground displacement. We found a negative relationship between water level change and ground deformation around the reservoir that was consistent across all sensors. The negative relationship was evident from the long-term changes in water level and deformation occurring from 1995 to 2014, and also from the intra-annual oscillations of the later period, 2014 to 2019, both around the reservoir and at the dam. These results suggest an elastic response of the ground surface to changes in water storage in the reservoir, both at the dam site and around the reservoir. Our study illustrates how InSAR-derived ground deformations can be consistent in time across sensors, showing the potential of detecting longer time-series of ground deformation.

Highlights

At larger scales, temporal mass changes in the Earth system due to terrestrial water storage are known to lead to gravity field variations and deformations at the Earth’s surface [1]
We found a negative relationship between ground deformation and water level throughout the period 1995–2019, evident across most radar sensors and present around the reservoir, across different geological units, and even at the dam site
Our study was novel in a way that it made an examination across sensors of the relationship between water level changes in the reservoir and ground displacement

Summary

Introduction

Temporal mass changes in the Earth system due to terrestrial water storage are known to lead to gravity field variations and deformations at the Earth’s surface [1]. This is why along with tectonics, Holocene sediment compaction, sediment loading, and glacial isostatic adjustment, water exploitation is regarded as a primary driver of ground surface deformation [2]. Fluctuations in water storage due to water management (i.e., withdrawal, storage or use) can sometimes be large enough to induce ground surface deformations of several centimeters [3,4], affecting human settlements and infrastructure stability [5]. Associated large surges of water can lead to dam instability, threatening lives and properties along the shores [9,10,11,12]

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