Newsletter and Technical Publications
Freshwater Management Series No. 5
Guidelines for the Integrated Management of
- Phytotechnology and Ecohydrology -
Kriging - an interpolation
technique based on a theory of the semivariogram.
Layer - a logical set of thematic data covering one subject.
Map projection - a set of
mathematical equations for converting geographical coordinates to Cartesian
plane coordinates. The equations allow
the depiction of spherical, three-dimensional objects on a flat map.
Metrics - a characteristic that changes in
some predictable way with increased human influence (e.g., a scoring system).
Model - a simplification and
abstraction of reality. Models can be seen as a data set representing the
structure of geographical objects, as well as a set of logical expressions and
mathematical equations used to simulate processes. Models may also be physical
representations of geographic features.
Multimetric approaches - an analysis technique using several measurable
characteristics of a biological assemblage.
Multispectral - the remote
sensing technique for obtaining images over number of distinct narrow bands of
the electromagnetic spectrum.
community analysis - statistical methods (e.g., ordination or
discriminant analysis) for analysing physical and biological community data
using multiple variables (quantitative or nominal).
Node - the end points of a line.
source pollution - pollution entering water bodies from diffused sources, including
surface and sub-surface runoff, nutrient leaching, and erosion, mainly from
degraded landscapes (e.g., landscapes degraded due to agriculture,
(Biogenics) - chemical elements necessary for growth and development of vegetation.
The main nutrients are phosphorus, nitrogen, and carbon. Increased nutrient
concentrations stimulate the process of eutrophication in aquatic ecosystems.
concentration - the amount of a nutrient in a given volume of water.
load - the amount of a nutrient transported into a water body by rivers, sewage
discharges, etc., over a given period of time, calculated as concentration
multiplied by discharge.
Phycocyanin - a photosynthetic
pigment characteristic of cyanobacteria.
Phytoplankton- the algal component of plankton,
which are free-living organisms within the aquatic environment.
Phosphatase - a group of hydrolytic enzymes
liberating the orthophosphate ion from organic compounds.
Piesometer - a pipe-like trap
for ground waters with perforated ends, placed in water bearing layers to
measure ground water elevations; when placed in fields, ground water flows can
be measured using tracers.
Pixel - one picture element (or cell) in a set of grid data.
Point source pollution - pollution entering water bodies from
concentrated outflows (e.g., pipes transporting municipal and industrial
sewerage, water from purification plants, irrigation channels, etc.).
Polygon - a vector representation
of an enclosed area written as a set of vertices or given by a mathematical
Radical zone - the surface
layers of the soil within the reach of plant roots.
Raster - a computer readable format used for
representing images or grid data.
Rasterization - the process of
converting data from vector format to raster format.
Reflectance - the ratio of
energy reflected by a surface to that incident upon it.
Retention time [also Water
retention time, WRT] - the ratio of volume and flow of a reservoir or lake.
Rubbersheeting - the procedure
for adjusting the geometry of an image by non-uniform transformations.
Reference condition - the chemical, physical, or
biological quality, exhibited at either a single site or an aggregation of
sites, representing a semi-natural or reasonably attainable condition at the
least impaired reference sites.
Scale - a relationship between the distance on a map and in reality.
Scanning - the process by which
analogue maps are converted to raster format by an optical device.
Semivariogram - a graph showing
the relationship between variance and separation for a pair of data points.
Shoal - a great number of fish swimming together.
Spatial interpolation - the
procedure of estimating values in certain areas using existing observations.
Stream microhabitat system - the distribution of pools, riffles, and runs,
having relatively homogenous substrate types, water depths, and velocities,
within a stream course (after Frissell et al. 1986)
Stream order - the dendritic arrangement of channels of a
river throughout its drainage basin. The most popular hierarchy is defined such
that first order streams are those having no tributaries, second order streams
are those formed by the union of two first order streams, third order streams
are those formed by the union of second order streams, and so on.
Stream pool-riffle-run system - a subsystem of a reach having characteristic bed
topography, water surface slope, depth, and velocity patterns.
In the natural meandering
watercourse, the shallow zones or riffles and the deeper zones or pools lie in
a regular pattern connected by runs. The distance between two neighbouring
riffles or pools is approximately one half of the wavelength of one full
meander, or about 5 to 7 times the width of the watercourse. In-stream habitats
at this level are complex hydrological units (after Frissell et al. 1986).
Stream reach - a length of stream or a stream segment lying between breaks
slope, local side-slopes, valley floor widths, riparian vegetation, and bank
materials (after Frissell et al. 1986).
Stream segment - the portion of a stream system
flowing through a single bedrock type and bounded by tributary junctions or
Stream system - all running surface waters in a watershed
(after Frissell et al. 1986); standing waters within stream systems may be
wetlands or lakes depending upon their depth, hyrdologic conditions, soil
types, and vegetation cover.
Succession - the biological
concept implying a sequence in which species or groups of species dominate a
Surface - a representation of
geographical object as set of continuous data (also, a data field).
Surface runoff - surface flow
caused by rainfall, transporting solids, nutrients, and pollutants downhill
into aquatic systems.
Topology - the spatial
relationship between nodes, lines, and polygons.
Vector - a data structure in
which lines are represented as a list of ordered coordinates.
Vectorization - the process of
converting data from raster to vector formats.
Vertex (vertices) - a point or
series of points with given coordinates on a line.
Wetland - a natural or constructed system, permanently or periodically flooded,
that can act as water purification systems or nutrient sinks. Purification is
enhanced by the activity of vegetation and variety of microbiological and
biogeochemical processes taking place within the substrate of the wetland.
Wetlands are defined by the presence of hydric soils, characteristic types of
vegetation, and an high water table.