Geoscience Reference
In-Depth Information
Soil Moisture Characteristics Curves or functions relating soil moisture content to unsaturated hy-
draulic conductivity and capillary potential [Section 5.1.1; Box 5.2]
Specific Moisture Capacity The gradient of the curve relating unsaturated soil moisture to capillary
potential [Section 5.1.1; Box 5.1]
State Variable A variable in a model that is part of the solution of the model equations and varies with
time during a simulation but which is not a flux or exchange of mass. May include storage and pressure
variables, depending on the definition of the model [Section 5.8]
Stemflow Rainfall that reaches the ground via the stems of plants [Section 1.4; Box 3.2]
Stochastic A model is stochastic if, for a given set of intial and boundary conditions, it may have
a range of possible outcomes, often with each outcome associated with an estimated probability
[Section 1.7]
Storm Profile Time series of rainfall intensities during a storm [Section 3.1]
Storm Runoff There are many conflicting definitions of storm runoff. Here it is that part of the stream
hydrograph due to a rainfall event over and above the discharge that would have occurred without a
rainfall event and may involve both surface and subsurface flow processes, and both event and “old”
water contributions [Sections 1.4, 1.5, 1.6]
Streamline A line following the direction of flow of water in a stream, aquifer or other flow domain
[Section 3.7]
Stream Tube The cross-sectional area bounded by surfaces following streamlines in a stream, aquifer
or other flow domain [Section 3.7; Box 11.1]
Sublimation Direct
loss of water
from a snowpack to the atmosphere by evaporation
[Section 3.1]
Subsurface Stormflow The contribution to the stream hydrograph generated by purely subsurface flow
processes [Section 1.4]
Superposition The addition of linear model responses to construct a total response [Section 2.2;
Box 2.1]
Surface Runoff The contribution to the stream hydrograph from overland flow [Section 1.4]
Tessellation The
discretisation
of
space
into
a
spatial
grid
or
network
of
elements
[Section 3.7]
Throughfall Rainfall that reaches the ground either directly or indirectly by dripping from the leaves
of plants [Section 1.4; Box 3.2]
Throughflow Often used for rapid near-surface downslope subsurface flow in the soil profile
[Section 1.4]
Time Compression Assumption Treating the volume of infiltrated water during an event as if it had
infiltrated at the infiltration capacity of the soil in order to calculate an equivalent time to ponding
[Box 5.2]
Time to Ponding The time taken during a rainfall event to bring the soil surface just to saturation
[Box 5.2]
Top-down Modelling Using the available observational data to suggest appropriate model structures,
usually applied at the catchment scale [Chapter 4]
Transfer Function A representation of the output from a system due to a unit input [Section 2.2,
Chapter 4]
Transit Time Distributions, Travel Time Distributions The distribution of times taken by water to
move through a hillslope, channel network or catchment. Used to indicate both the transit or travel
times for an increment of input to reach an outlet and the transit or travel times for an increment
of discharge to reach the outlet. These are different and should be properly differentiated (see also
Residence Time Distributions) [Section 11.8-11.10]
Triangular Irregular Network A way of representing topography by a network of triangles between
points of known elevation [Section 3.7]
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