[1] Tide-induced variations in subsurface air pressure, mainly between 1.0 to 2.0 kPa, are observed in coastal areas in Hong Kong. A two-dimensional model which couples the two-phase air-water flow in unsaturated and saturated zones successfully reproduces the observed air pressure under no rain conditions. The simulation reveals that significant increases in air pressure depend on the tidal ra...

Herbicide atrazine easily leaches to groundwater, where it is persistent. We studied whether sonication accelerates atrazine dissipation (100 mg·L−1) in vadose zone sediment slurries. Sediments were from 11.3 to 14.6 m depths in an atrazine-contaminated groundwater area. The slurries and autoclave-sterilized slurries were sonicated (bath, 43 kHz, 320 W) for 0, 5, 10, 20, or 30 min once/twice a ...

Research Objectives: This project seeks to improve the basic understanding of colloid and colloid-facilitated transport of Cs in the vadose zone. The specific objectives are: • Determine the structure, composition, and surface charge characteristics of colloidal particles formed under conditions similar to those occurring during leakage of waste typical of Hanford tank supernatants into soils a...

We derive 1D steady equilibria for partially saturated downslope flow as a solution to the reposed vadose-zone problem. The equilibria are determined by two free parameters: a mean flow and a downstream saturation. Where there is no downstream saturation, a uniform outflow of constant saturation is obtained, but if an isolated zone of excess downstream saturation exists, the upstream flow speed...

Getting into the heart of water movement vadose zone is essential due to direct impact on aquifer recharge, flood hazards, irrigation planning and resources management in general. Since soil profiles nature appear layers, present study accomplishes a deep investigation water’s motion through layers with different hydraulic properties. A series experiments were conducted laboratory where infiltr...

Considering three sites under different climate conditions (arid, semi-arid, and subhumid), this study aims to use the vadose-zone water stable isotope profiles estimate groundwater recharge rate. High-resolution vertical subsurface soil sampling along vadose zone of investigated was conducted. The collected samples were analysed determine their ratios (δ2H δ18O) that used with piston displacem...