Geoscience Reference
In-Depth Information
soil suction
A measure of the strength of the cap-
illary forces. This is also called the moisture tension
or soil water tension. A dry soil exerts a high soil
suction.
soil water
Water in the unsaturated zone occurring
above a water table. This is also referred to as water
in the vadose zone.
synthetic unit hydrograph
A unit hydrograph
derived from knowledge of catchment character-
istics rather than historical hydrograph records.
tensiometer
An instrument used to measure the
soil moisture tension.
Thiessen's polygons
A method of estimating
average rainfall for an area based on the spatial dis-
tribution of rain gauges.
throughfall
The precipitation that falls to the
ground either directly (through gaps in the canopy),
or indirectly (having dripped off leaves, stems or
branches).
throughflow
Water which runs to a stream
through the soils. This is frequently within the
unsaturated (vadose) zone. This is one form of
runoff. Sometimes referred to as lateral flow.
time domain reflectometry (TDR)
A method to
estimate the soil water content based on the inter-
ference of propagated electromagnetic waves due to
water content.
specific heat capacity
The amount of energy
required to raise the temperature of a substance by
a single degree.
SPOT
French satellite to study the earth's surface.
stage
In hydrology this term is used to mean the
water level height of a river.
stemflow
Rainfall that is intercepted by stems and
branches, and flows down the tree trunk into the
soil.
stomatal or canopy resistance
The restriction a
plant places on its transpiration rate through open-
ing and closing stomata in the leaves.
storage
A term in the water balance equation to
account for water that is not a flux or is very slow
moving. This may include snow and ice, ground-
water and lakes.
storm duration
The length of time between
rainfall starting and ending within a storm.
stormflow
The portion of streamflow (normally
seen in a hydrograph) that can be attributed to
storm precipitation. Sometimes also referred to as
quickflow or peakflow.
total dissolved solids (TDS)
The amount of solids
dissolved within a water sample. This is closely
related to the electrical conductivity of a water
sample.
total suspended solids (TSS)
The amount of
solids suspended within a water sample. This is
closely related to the turbidity of a water sample.
transpiration
The movement of liquid water from
a plant leaf to water vapour in the atmosphere.
Plants carry out transpiration as part of the photo-
synthetic process.
turbidity
The cloudiness of a water sample.
ultrasonic flow gauge
An instrument that mea-
sures stream discharge based on the alteration to a
propagated wave over a known cross section.
stream
A small river.
streamflow
Water flowing within a stream chan-
nel (or river flow for a larger body of water). Often
referred to as discharge.
suction moisture curve
See
soil moisture char-
acteristic curve
.
Synthetic Aperture Radar (SAR)
A remote sens-
ing technique that uses radar properties, usually of
microwaves.
unit hydrograph
A model of stormflow in a
particular catchment used to predict possible future
storm impacts. It is derived from historical hydro-
graph records.
