Présentations Colloques

Oral Presentation
Session 8.07: Hydrogeophysics: innovative non-invasive technologies for groundwater resources exploitation and management
Payal Rani
Application of time-lapse electrical resistivity tomography and groundwater simulation models to monitor the transport of organic contaminants under unsaturated and saturated conditions
Production of olive oil is one of the most important activities in the Mediterranean area, particularly in Greece, which holds the third place worldwide after Spain and Italy. For every tone of produced olive oil, about 25% of liquid wastes (olive oil mill wastes- OOMWs) enriched with organic load and inorganic constituents are produced. The OOMWs are usually disposed in uncontrolled, unprotected and poorly constructed shallow evaporation ponds, causing several ecological problems such as odour, increased salinity, toxicity to soil and contamination to surface water bodies and groundwater. A pilot study area (an evaporation pond of OOMWs) has been constructed in Western Crete, at Alikianos village, very close (about 15 meters) from Keritis river. **During the last decades, geophysical methods have gained popularity as efficient tools for monitoring the changes of subsurface physical properties over time and identifying the spatial distribution of pollutants.**The OOMWs are mainly characterized by high electrical conductivity values and high concentration of phenolic compounds. Those characteristics of OOMWs can be used for detecting them and in particular using geoelectrical methods. **In the present study, time-lapse electrical resistivity tomography (ERT) and self-potential techniques are used to map and monitor the subsurface contamination caused by OOMW. A three-dimensional finite-element model for groundwater flow and transport is developed to estimate the temporal and spatial distribution of the selected contaminant under unsaturated and saturated conditions. The resulted simulation models are verified by the obtained time-lapse two-dimensional ERT geophysical inversion images. Results of geochemical analysis of soil and liquid samples collected from two soil profiles excavated along the ERT profile have been used for calibration and validation of both simulation and geophysical results.**