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Summary of Proposal GEO3155

TitleMeasurement of time-dependent surface displacement associated with ground water extraction at Lorca (Murcia, Spain).
Investigator Abajo , Tamara - Consejo Superior de Investigaciones Científicas, Instituto de Geociencias
Team Member
Mrs. Abajo, Tamara - Consejo Superior de Investigaciones Científicas, Institute of Geosciences
Mr. Fernández, José - Consejo Superior de Investigaciones Científicas, Institute of Geosciences
Mr. Escayo, Joaquín - Consejo Superior de Investigaciones Científicas, Institute of Geosciences
SummaryGlobally,groundwater depletion rates have risen in recent decades, and significant groundwater-table drops have been reported(Wada et al., 2010). For example, the peri-Mediterranean coastal areas have been subjected to rapid developments in tourism, residential urbanization, and intensive agriculture. As a consequence, land-use change has increased water resource demand (Coccossis and Hénocque, 2001). Extraction of groundwater can partially supply the increased freshwater demand, but if the extraction rate exceeds some sustainable limit, it can lead to aquifer overdrafting.The lowering of the groundwater table is a significant problem in Mediterranean coastal areas, leading to salt water intrusion, drying of wetlands, and the disappearance of rivers(Coccossis and Hénocque, 2001). Aquifer overdraft has been a concern for the management of the water resources, due to the potential irreversible loss of aquifer storage caused by aquifer-system compaction, and associated land subsidence(Galloway and Hoffmann, 2007). From a mechanical point of view,groundwater extraction from a confined aquifer reduces groundwater pore pressure. Because the overburden remains unchanged, the effective stress on the grain matrix of the aquifer increases, and the volume of the confined aquifer decreases,resulting in compaction and triggering surface subsidence.Therefore, the control of land subsidence could serve as a proxy for the management of the pore-pressure change and groundwater flows in underlying aquifers (Galloway and Hoffmann,2007). This project aims to study the occurrence of surface displacement associated with the exploitation of aquifers,at regional and local scales, in the southern part of the Iberian Peninsula, in particular in Lorca (Murcia) region. This study is going to combine space and terrestrial observation techniques for the detection and monitoring of deformation. This will be done through the merging and integration of these different data sources to obtain the 3D surface deformation with high spatial density. This allow to have a picture as accurate as possible of the displacement field and therefore, of the different parameters associated with the studied phenomenon. The last point will be done by means of the development of ad-hoc models and inversion techniques. The use of the second generation of radar satellites data will permit to perform these studies on a regional scale covering large areas, complementing the usual study done at a local scale. It will be done by using multi-satellite and multifrequency radar observation, allowing to obtain pixel sizes ranging from 60-90 m2to 1-5 m2(corresponding to observation in C and X bands respectively). This deformation study will be complemented by the development,improvement and implementation of the necessary tools that will allow modeling and interpretation of the observations, as well as to evaluate possible interactions with other phenomena, such as the potential to influence faulting on nearby faults. Funds supporting the cost of this project will be provided by the project AQUARISK (composed by the sub-projects ESP2013-47780-C2-1-R and ESP2013-47780-C2-2-R) with duration from 01/01/2014 to 31/12/2017, and supported by the Spanish“Ministerio de Economía y Competitividad” (MINECO). This project has a total funding of 326.752,14 €, being its coordinator JoséFernández (IGEO, CSIC), one of the Co-PI of this proposal. References Coccossis,H., and Henocque, Y., 2001, White paper coastal zone management inthe Mediterranean: U.N. EnvironmentProgramme,Priority Actions Programme, United Nations. Galloway,D. L., Hoffmann, J., 2007. The application of satellite differential SAR interferometry-derived ground displacements in hydrogeology. Hydrogeology Journal, 15, 133-154. Wada, Y., et al., 2010, Global depletion of groundwater resources: Geophysical Research Letters, v.37, L20402, doi:10.1029/2010GL044571.

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