A quasi three-dimensional (QUASI 3-D) model is presented for simulating the subsurface water flow and solute transport in the unsaturated and in the saturated zones of soil. The model is based on the assumptions of vertical flow in the unsaturated zone and essentially horizontal groundwater flow. The 1-D Richards equation for the unsaturated zone is coupled at the phreatic surface with the 2-D ...

According to the characteristics of groundwater in arid area, this paper proposes DRAV model for groundwater vulnerability assessment, where D is groundwater depth, R is the net recharge of aquifer, A is the aquifer characteristics, and V is the lithology of vadose zone. As a case study, the paper assesses the vulnerability of pore phreatic water in Tarim Basin of Xinjiang, China by using the D...

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...

The Delmarva Peninsula is located on the East Coast of the United States, between the Chesapeake Bay and Atlantic Ocean. Industrial farming in the Delmarva Peninsula leads to levels of nutrients, in particular nitrogen, which grossly exceed natural levels. Excess nitrogen reaches the freshwater streams of the peninsula, which then flows to the Chesapeake Bay. The presence of extreme levels of n...

Rhizobial symbionts were isolated from the surface (0–0.5 M) and phreatic (3.9–5.0 M) root environments of a mature mesquite woodland in the Sonoran Desert of Southern California, and from variable depths (0–12 m) of non-phreatic mesquite ecosystems in the Chihuahuan Desert of New Mexico. They were tested for their ability to tolerate high salinity, and respire NO3 2 as mechanisms of free-livin...

The Pantanal of Nhecolândia, the world's largest and most diversified field of tropical lakes, comprises approximately 10,000 lakes, which cover an area of 24,000 km(2) and vary greatly in salinity, pH, alkalinity, colour, physiography and biological activity. The hyposaline lakes have variable pHs, low alkalinity, macrophytes and low phytoplankton densities. The saline lakes have pHs above 9 o...

The unsaturated zone and the saturated/unsaturated interface region are important links between groundwater and the land surface. They provide storage capacity for both water and contaminants; a reactor medium for physical, chemical and biological processes; a delay time between the release of a contaminant into the unsaturated zone and its influx into the saturated zone and, a domain for the l...