Geoscience Reference
In-Depth Information
hydrograph
A continuous record of streamflow.
hydrograph separation
The splitting of a hydro-
graph into stormflow and baseflow.
hydrological cycle
A conceptual model of how
water moves around between the earth and atmos-
phere in different states as a gas, liquid or solid. This
can be at the global or catchment scale.
hydrology
'The science or study of' ('logy' from
Latin
logia
) and 'water' ('hydro' from Greek
hudor
).
Modern hydrology is concerned with the distri-
bution of fresh water on the surface of the earth and
its movement over and beneath the surface, and
through the atmosphere.
hydrometry
The science of streamflow measure-
ment.
hydrophobicity
and
hydrophobic soils
The
ability of some soils to rapidly swell upon contact
with water so that the initial infiltration rate is low.
In this case the water will run over the surface as
infiltration excess overland flow.
hypsometric method
A method for estimating
areal rainfall based on the topography of the area
(e.g. a catchment).
hysteresis
The difference in soil suction at a given
water content dependent on whether the soil is
being wetted or dried (see soil moisture charac-
teristic curve).
infiltration capacity
The rate of infiltration of
water into a soil when a soil is fully saturated (i.e.
at full capacity of water).
infiltration excess overland flow
Overland flow
that occurs when the rainfall rate exceeds the infil-
tration rate for a soil. Also referred to as Hortonian
overland flow.
infiltration rate
How much water enters a soil
during a certain time interval.
infiltrometer
An instrument to measure the infil-
tration rate and infiltration capacity for a soil.
instream flow assessment
A combination of
hydrology and aquatic ecology used to assess how
much water, and the flow regime, that is required
by particular aquatic fauna in a river or stream.
integrated catchment management (ICM)
A
form of integrated water resource management
(IWRM) that promotes the river catchment as the
appropriate organising unit for understanding and
managing water-related biophysical processes in a
context that includes social, economic and political
considerations. Also sometimes referred to as
Integrated Water Basin Management - IWBM.
integrated water resource management
(IWRM)
A water resource management paradigm
that promotes the coordinated development and
management of water, land and related resources in
order to maximise the resultant economic and social
welfare in an equitable manner without compro-
mising the sustainability of vital ecosystems.
interception
The interception of precipitation
above the earth's surface. This may be by a vegeta-
tion canopy or buildings. Some of this intercepted
water may be evaporated; referred to as interception
loss.
isohyetal method
A method for estimating areal
rainfall based on the known distribution of rainfall
within the area (e.g. a catchment).
jökulhlaup
The flood resulting from an ice-dam
burst.
kriging
A spatial statistics technique that identifies
the similarity between adjacent and further afield
point measurements. This can be used to interpolate
an average surface from a series of point measure-
ments.
LANDSAT (LAND SATellite)
A series of satel-
lites launched by the North American Space Agency
(NASA) to study the earth's surface.
latent heat
The energy required to produce a phase
change from ice to liquid water, or liquid water to
water vapour. When water moves from liquid to gas
this is a negative flux (i.e. energy is lost), whereas
the opposite phase change (gas to liquid) produces
a positive heat flux.
