Geography Reference
In-Depth Information
Water quality is also defined as a consequence of natural physical and
chemical state of water (surface or subsurface) as well as alterations caused by
human activities (Fetter, 1994). The quality of water is a measure of its
suitability as a water supply source for domestic and agricultural consumption
as well as for irrigation, industrial and other purposes; the suitability of water
is decided based on criteria for various uses and water quality standards. The
definition of water quality is therefore not objective; rather it is socially
defined depending on the desired use of water. Different water uses require
different standards of water quality and water quality criteria define desirable
characteristics and acceptable levels of constituents for water of various
intended uses (Freeze and Cherry, 1979; Todd, 1980; McCutcheon et al.,
1993; Fetter, 1994). To establish quality criteria, the measures of
physical
,
chemical
, and
biological
constituents must be specified, together with standard
methods for comparing results of water quality analyses (Todd, 1980;
McCutcheon et al., 1993). The pollution of the aquatic environment can be
defined as introduction of substances or energy by man, directly or indirectly,
which result in such deleterious effects as harm to living resources, hazards to
human health, hindrance to aquatic activities including fishing, impairment of
water quality with respect to its use in agricultural, industrial and often
economic activities (Meybeck and Helmer, 1992), and reduction of amenities
(GESAMP, 1988). The term
pollution
refers to changes caused by humans and
their actions that result in water-quality conditions that negatively impact the
integrity of the water for beneficial purposes, including natural ecosystem
integrity (Johnson, 2009). Determining the extent of pollution is difficult,
given the wide range of constituent measures that characterize water quality
(e.g., dissolved and suspended solids, organics, bacteria, toxics, and metals).
Evaluation of water quality, assessment of spatial and temporal variations
and its vulnerability mapping are among the important tasks in order to
manage quality of the useful water resources.
There are many tools and techniques for evaluating the water quality and
geographic information system is one of them, which is gaining a wide
popularity nowadays because of several advantages of the technique.
Geographic Information System (GIS)
has emerged as a powerful tool for
capturing, storing, analyzing, manipulating, retrieving and displaying spatial
data and using these data for decision making in several areas including
engineering and environmental fields (e.g., Stafford, 1991; Goodchild et al.,
1993; Burrough and McDonnell, 1998; Lo and Yeung, 2003). It allows for
swift organization, quantification and interpretation of a large volume of
spatial data with a computer accuracy and minimal risk of human errors.
