Characterization of LNAPL distribution in whole domains subject to precipitation by the simplified image analysis method

The Simplified Image Analysis Method (SIAM) is a laboratory technique devised to assess the three-phase dynamic saturation of water and Non-Aqueous Phase Liquids (NAPLs) in granular soils. This method is based on an extension of the Beer-Lambert Law of Transmittance that establishes a linear relationship between the saturation of water (S-w), NAPL (S-o), and their corresponding average optical densities (D-i), for pictures taken using two consumer-grade digital cameras attached to two band-pass filters (wavelengths lambda = 450 and 640 nm). In this study, we use SIAM to characterize the migration of diesel (density rho = 0.865 g/cm(3), viscosity nu = 7 mm(2)/s), a Light NAPL (LNAPL), when subject to different precipitation conditions (precipitation intensity i = 6.6 and 63.2 mm/h) in a one-dimensional column (3.5x3.5x50 cm) filled with Toyoura sand (particle density rho(S) = 2.65 g/cm(3), equivalent grain size D-60 = 0.196).