A fully instrumented field station to monitor essential unsaturated soil variables: Records and lessons during the Medicane Daniel

¹ University of West Attica, Civil Engineering Department, 250 Thivon & Petrou Ralli, 12244 Egaleo, Greece
² Edafos Engineering Consultants S.A., Laboratory, 2 Therapion st., 10444 Athens, Greece

Abstract

This paper provides an overview of the development and current capabilities of a field station designed to monitor unsaturated soil variables at multiple depths and presents and discusses the elaborated recorded response data. Located in the backyard of Soil Mechanics Laboratory (SOMELAB) at University of West Attica (UNIWA), the station is equipped with various advanced tools and sensors, which monitor soil conditions down to 1.30 meters depth. Porous block sensors measuring soil suction have been installed at three distinct depths (0.45m, 0.70m, and 1.30m), supplemented by a volumetric water content sensor at 0.45m. Three tensiometers have been placed at the same depths to compare with the porous block sensors. An active, fully equipped meteorological station on the rooftop of a nearby building provides essential free field rainfall data for the station’s operation. During the installation, soil samples were collected from each of the monitored layers and subjected to a complete set of laboratory tests for their physical properties as well as the SWCC. These data and tests are vital for establishing a complete monitoring system for unsaturated soil properties and understanding how these variables vary throughout a hydrological year, in relation to both depth and soil characteristics. The sensors have responded during two rainfall events of cumulative rain of 100mm in a single day and 60mm in three days, in a similar way but for a different zone of influence. The range of typical yearly suction during the dry season is typically out of the tensiometer’s capacity. The collected field data align with initial expectations, and additional laboratory and field tests and instrumentation have been planned to facilitate the project’s progress.