USGS tackles invasive species

MINING: EPA Tackles Fracking

Invasive Species

Biological invasion The process by which an organism is introduced to, and establishes a sustainable population in, a region beyond its native range. Eradication The managed extirpation of an entire nonnative population. Impact The effect of a nonnative species on its environment. Invasibility The vulnerability of a habitat, community, or ecosystem to invasion. Invasion ecology A multidisciplin...

Invasive Species

Invasive species are characterized by their substantial population growth and spread outside their native ranges. Humans originally introduced most of today’s invasive species, and all regions on Earth have been affected by invasive species to some extent. Curiously, 90% or more of introduced species do not become invasive pests; rather, they die out or rely on direct human assistance to achiev...

Invasive species

An invasive species is one that arrives (oftenwith human assistance) in a habitat it had not previously occupied, then establishes a population and spreads autonomously. Species invasions are one of the main conservation threats today and have caused many species extinctions. The great majority of such invasions are by species introduced from elsewhere, although some native species have become ...

USGS directions in MODFLOW development.

Introduction The development and application of ground-water models has been an important component of USGS hydrologic investigations since the early 1970s. During the past 35 years, the USGS has developed a wide range of computer models to simulate saturated and unsaturated subsurface flow, solute transport, and chemical reactions. The most widely used of these programs is the MODFLOW model, w...