Geography Reference
In-Depth Information
GIS is an effective tool for analyzing spatial and temporal data of water
quality (Burrough and McDonnell, 1998; Gurnell and Montgomery, 2000;
Chang, 2002; Chen et al., 2004). Information on spatial and temporal
variability/trends of water quality is very helpful in the decision-making
process (Freeze and Cherry, 1979; Todd, 1980; Fetter, 1994). In addition,
water quality mapping is essential for monitoring, pollution hazard
assessment, modeling and environmental change detection (Goodchild et al.,
1993; Skidmore et al., 1997; Chen et al., 2004; Jha et al., 2007). In a GIS
framework, point estimates of water quality parameters can be spatially
interpolated by spatial interpolation techniques such as kriging, inverse
distance weighting, etc. to develop parameter concentration maps at different
time scales or other related maps. GIS presents spatial information in the form
of maps where different features are located by symbols, and is integrated with
databases containing multiple attributes' data of the mapped features. A map
helps providing knowledge of where and what things are, and how they are
related. The GIS database containing spatial and point attributes can then be
used to generate interactive reports and maps, which in-turn can support
decision-making about the best design alternatives and their impacts.
Furthermore, GIS-based maps serve as powerful communication medium in
presenting information in such a way that the people involved in the planning
and management of water quality can better understand and get more involved.
This chapter deals with various methods, i.e., statistical properties,
vulnerability mapping, water quality indices, etc. for water quality evaluation
using integration of the GIS technique. In all the methods, central role of GIS
technique in water quality evaluation is highlighted.
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OINT AND
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OINT
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OURCES OF
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OLLUTION
GIS plays a central role in water quality management practice and
augments efforts to monitor water quality changes in surface waterbodies or
aquifers, to calculate pollutant concentrations and loads to a surface waterbody
or groundwater, and model water quality of aquatic systems (Johnson, 2009).
Water quality protection and management require quantity of the waste-
assimilative capacity of receiving waters to be known, which is determined
using the concept of
„total mass daily loading‟
(TMDL). A TMDL is assessed
taking account of all sources of a pollutant, from both point and nonpoint
sources, and the waste assimilative capacity of the receiving water body
(USEPA, 1991).
