Ground Subsidence Triggered by the Overexploitation of Aquifers Affecting Urban Sites: The Case of Athens Coastal Zone along Faliro Bay (Greece)

Agavni Kaitantzian,Isaak Parcharidis,Ploutarchos Tzampoglou,Constantinos Loupasakis

doi:10.1155/2020/8896907

Abstract

Land subsidence in the coastal zone of the Neo Faliro, Moschato, and Kallithea municipalities, along the Faliro bay, has been recorded since the mid 1960’s. This phenomenon has caused damage to buildings, pavements, and roads. Aiming to identify the main causes of the observed ground deformations, data referring to the geological, geotechnical, and hydrogeological settings of the study area has been evaluated. Subsidence has been quantified by the use of space-born Synthetic Aperture Radar interferometry (InSAR) techniques. SVD (Singular Value Decomposition) and IPTA (Interferometric Point Target Analysis) techniques have been applied for the production of deformation maps, referring to the time period between 2002 and 2010. Furthermore, aiming to extend the study of the phenomenon further to the past, Persistent Scatterer Interferometry (PSI) data for the time period from 1992 to 2001 were also evaluated. Finally, the results of the InSAR analysis have been crosschecked with measurements acquired by a vertical geodetic control network as well as by ground truth data, referring to damage inventory of the site. The current research presents an interesting case study of an urban site affected for a long-lasting period by the activities of a neighboring industrial zone. The development of an extensive depression cone, mainly due to the overexploitation of the aquifers for industrial use, is the main cause of the land subsidence phenomenon, without excluding a component of motion due to the natural compaction of the compressible soil in the area of interest. The complexity of the geological, hydrogeological, and geotechnical conditions and the interaction of the numerous land use activities make this study far more interesting.

Highlights

IntroductionLand subsidence is considered as one of the most frequent geological hazard that usually occurs as a consequence of a number of causes, namely, groundwater overexploitation [1,2,3,4,5], organic soils oxidation [6, 7], and collapse of underground cavities [8,9,10].The effects of this geohazard include significant damage to buildings as well as loss of functionality of linear and point infrastructures (pipeline and road network deformations, well-casing failures, and protrusion, etc.) [11, 12].Detecting, measuring, and monitoring land subsidence is important for urban and infrastructure planning as well as for risk management
The present study provides a methodological approach for the identification of the subsidence mechanism by combining the geotechnical characteristics with the hydrogeological data and by verifying the displacements with the use of space-born Synthetic Aperture Radar (SAR) interferometry (InSAR) techniques and ground truth geodetic measurements
As proved by the groundwater leveling data, the industrial zone extending at the north of the study area, due to the overexploitation of the aquifers, causes the development of an extensive depression cone, extending down to the coastline

Summary

Introduction

Land subsidence is considered as one of the most frequent geological hazard that usually occurs as a consequence of a number of causes, namely, groundwater overexploitation [1,2,3,4,5], organic soils oxidation [6, 7], and collapse of underground cavities [8,9,10].The effects of this geohazard include significant damage to buildings as well as loss of functionality of linear and point infrastructures (pipeline and road network deformations, well-casing failures, and protrusion, etc.) [11, 12].Detecting, measuring, and monitoring land subsidence is important for urban and infrastructure planning as well as for risk management. Land subsidence is considered as one of the most frequent geological hazard that usually occurs as a consequence of a number of causes, namely, groundwater overexploitation [1,2,3,4,5], organic soils oxidation [6, 7], and collapse of underground cavities [8,9,10] The effects of this geohazard include significant damage to buildings as well as loss of functionality of linear and point infrastructures (pipeline and road network deformations, well-casing failures, and protrusion, etc.) [11, 12]. Characteristic examples of such areas are Thessaly plain in central Greece [31,32,33,34], the wider area close to Kalochori and Sindos villages west of the Thessaloniki plain [35,36,37,38], the Anthemountas basin at the east of Thessaloniki [39,40,41,42]

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