Image analysis for soil dye tracer infiltration studies

Flow processes in soils are closely related to groundwater quality often affected by human activities. Because hydrological models usually lack explanatory power, direct visualization of flow paths in dye tracer infiltration studies has become a standard tool in soil hydrology. These experiments provide images of dye-stained paths in soils and help evaluating the vulnerability or understanding the general hydrological functioning of a given site. Extracting relevant information demands expertise in hydrology as well as in image analysis and statistics. To our knowledge, no agreed and effective method to analyze large collections of such images exists in the soil hydrology community. In this paper we propose a general framework consisting of index functions and visual tools to support the expert in his/her evaluation of dye tracer infiltration images.