Environmental Engineering Reference
In-Depth Information
Capillary water
Water held within the capillary pores of soils; mostly available to
plants.
Carbonation
The solution of carbon dioxide in water, forming weak carbonic acid which
enhances its 'aggressivity' or solution potential; a key preliminary stage in the solution
of limestones.
Carnivores
Organisms which are flesh-eating and therefore occupy the third or higher
trophic level
in
ecosystems
.
Cascading system
A system composed of a chain of subsystems which have both spatial
magnitude and geographical location, and which are linked by a cascade of mass or
energy.
Catchment
A three-dimensional landsystem or
drainage basin
which converts
precipitation and groundwater inputs to stream flow and whose components are
assessed in terms of their influence on these processes.
Catena
The sequence of soils which occupy a slope transect, from the topographic divide
to the bottom of the adjacent valley.
Cation
An atom which has lost one or more negatively charged electrons and is thus
itself positively charged.
Cation exchange
The process whereby cations in the soil solution exchange with those
adsorbed on soil colloids.
Cation exchange capacity (CEC)
The total amount of exchangeable cations which a soil
can adsorb on its colloidal surfaces.
Cavitation
The implosion of bubbles or cavities against a channel wall during rapid,
turbulent stream flow and its enhancement of fluid shear stress.
Chamaephytes
Plants which hug the ground surface and where buds are located on the
ground surface.
Channel flow
The confinement and concentration of surface water movement in a fluvial
channel.
Channel network
The pattern and connectivity of all channels draining a
catchment
.
Channel segment
A short length of fluvial channel selected for the purpose of assessing
or modelling relations between channel geometry, stream discharge and sediment
transfer.
Chelate
A complex organic compound containing a central metallic ion (e.g. iron,
calcium, copper) surrounded by organic chemical groups.
Chelating agent
An organic substance capable of weathering metallic ions from rock, or
moving metallic ions in soils.
Chelation
The process of forming
chelates
, usually by means of organic acids or organic
salts.
Chemical energy
A form of energy bound up within the chemical structure of a
substance.
Chemical sediment
A non-
clastic
and often crystalline sediment, derived from mineral
or organic sources and formed by precipitation from a solution or suspension.
Chemical weathering
The disaggregation of rock mass caused by chemical alteration of
some or all of its constituent minerals in the conditions prevailing at or near the land
surface.
