Laboratory and Field Performance Evaluation of Low-Cost Conductivity Sensors

An artificial aquifer facility or physical sandbox model was built to conduct laboratory large scale infiltration and tracer tests, aiming to determine the soil infiltration rate and the contaminants retention and/or degradation capacity, namely to simulate Soil-Aquifer Treatment (SAT) in a Managed Aquifer Recharge (MAR) basin. Conductivity sensors (EC) were tested in this physical sandbox model and in the field MAR basin. Calibration and validation of the conductivity sensors were conducted against CDT diver multi-parameter groundwater data loggers. Sodium chloride was used as a tracer, in order to create a conductivity pattern in the porous media. The conductivity dynamics in the porous media were captured by the conductivity sensors. The validation procedure was conducted in order to understand the measurements taken from different conductivity sensors at the same location. For each conductivity sensor, a regression analysis was carried out to compare the results between CDT diver and Libelium Conductivity Sensor. Based on linear regression analysis, coefficient of determination (R2) was calculated. For the conductivity sensors, the minimum and maximum R2 value obtained were 0.82 and 0.91 respectively, further indicating the linear relationship between the sensors used. Conductivity sensors are important to determine groundwater contamination. These EC sensors can give a better understanding of the pollutants which could be released in the ground and make their way down into the groundwater system.