As the number of impervious surfaces in urban environments increases, the ability of modified root zones to infiltrate water is becoming more important. Current methods of tracing water flow through soil profiles include excavating large pits in situ or analyzing soil cores in the laboratory with computed tomography or magnetic resonance imaging. While useful, these methods may not be suitable for urban settings or practical in every laboratory. We propose a new method that is less invasive, does not require extensive technical equipment and can reliably trace water movement through the soil profile in order to calculate flow rate based on the advancement of the wetting front. It was also realized that recording soil resistance during sampling could provide a better understanding of soil conditions influencing water movement. In this study soil cores 30 cm in length and 7.62 cm in diameter were obtained from golf course putting greens and green fluorescent water tracing dye was used in conjunction with UV light and time lapse photography to track movement of the wetting front. Images were processed with MATLAB and an algorithm was developed to quantify flow rates in mm sec-1. A soil sampler with a load cell sensor recorded the soil resistance during sampling. The flow patterns captured in this study illustrate the quick initial movement of water through preferential pathways and the slower absorption of micropores as infiltration progresses. This method has the potential to provide quality information on flow path development and evolution, changes in soil layering over time and flow rates during water infiltration.
Advisor: Roch Gaussoi
