Geoscience Reference
In-Depth Information
Turlough -
Areas seasonally l ooded by karst
ground water with sufi cient frequency and
duration to produce wetland characteristics.
Generally l ooded in winter and dry in
summer, i lling and emptying via under-
ground passages. Specii c to western Ireland.
Uniformitarianism -
Principle that modern
geologic processes are analogous to past pro-
cesses that shaped the Earth.
Várzea -
Portuguese term for nutrient-rich
forests growing on l oodplains adjacent
to Amazonia rivers. The Várzea River is a
tributary of the Uruguay River in southern
Brazil.
Vegetation index -
Ratio of red light to near-
infrared rel ectivity, which is an indication
of the amount of photosynthetically active,
emergent vegetation present in a scene,
such as an aerial photograph or satellite
image.
Vernal pond -
Shallow, intermittently l ooded
wet meadow and small pools. Typically of
Mediterranean climate; wetlands temporarily
l ooded during spring and dry in summer and
fall.
Vlei(s) -
Seasonal wetland(s) similar to dambo.
Term used in Zimbabwe and other parts of
southern Africa.
Vloer -
South African term for l at surface with
caked mud and high salt content, generally
devoid of vegetation; resembles playa. Etymol:
Afrikaans - l oor.
Wad (pl. Wadden) -
Unvegetated tidal l at on
the North Sea coast in the northern Nether-
lands and northwestern Germany. The term
is now used for coastal areas worldwide.
Water table -
Level to which water rises in a
well within an unconi ned aquifer or soil.
Waterfowl -
Aquatic birds that habitually swim
or dive, such as ducks, geese, pelicans, etc.
Wet meadow -
Grassland with waterlogged soil
near the surface but without standing water
for most of the year.
Wet prairie -
Similar to a marsh, but with water
level intermediate between a marsh and wet
meadow.
Wetland -
Area that is regularly wet or l ooded
and has a water table that stands at or above
the land surface for at least part of the year
during the growing season.
Wetlands Reserve Program -
U.S. program
authorized by the 1990 Farm Bill that pays
farmers who restore and protect once-farmed
wetlands in areas that are subject to periodic
l ooding.
Wrack -
Dead vegetation, thatch, specii cally
material washed up and deposited during
storm or high tide.
Zakaznik -
Russian nature sanctuary, many of
which were traditionally managed as game
reserves.
Zapovednik -
Russian nature preserve given
the highest level of environmental protection
to maintain wild conditions.
