The unsaturated zone consists of a complex arrangement of solid, liquid, and gaseous phases, most of them interconnected. The spatial distribution and geometrical arrangement of each phase, and the partitioning of solutes between phases, are controlled by physical, chemical, and biological processes. Since the upper part of the vadose zone is the most dynamic region, and controls the further do...

Artificial intelligence (AI) and machine learning (ML) have been recently applied extensively in various disciplines of vadose zone hydrology. However, not much attention has paid to their database-dependent accuracy uncertainty, reproducibility, delivery, which undermines applications real-world problems. We discuss lessons from the past emphasize need for lack fundamental protocols (i.e., det...

The Northern Guam Lens Aquifer (NGLA) presents unique challenges to modelers due to the complex hydrologic properties of its thick karst vadose zone. To meet these challenges, we developed VADOCHARGE, an analogue model based on the US Army Corps of Engineers’ Streamflow Synthesis and Reservoir Regulation (SSARR) model, to produce the effect of attenuated and lagged recharge through the vadose z...

near-surface environment. Also, many of the complicating effects found in the near-surface environment will Approaches for estimating liquid flux in the shallow (0–2 m) vadose be damped or eliminated with increasing depth. For zone are hindered by the high degree of spatial and temporal variability present near the land surface. It is hypothesized that high-frequency these reasons, flux measure...