Selection of variables to be sampled in water quality monitoring networks

The selection of water quality variables to be sampled is a highly complicated issue with significant cost implications since there are several variables to choose from. Essentially, there are five significant issues that need to be stressed regarding variables to be monitored: (a) variable selection should be based on objectives of monitoring; that is, the type and nature of information required for water quality assessment must be identified first; (b) the selection of variables should be realized by a systematic approach as a monitoring network itself is a family of systematically operated monitoring stations; (c) variable to be monitored, i.e., constituents and pollutants, should be selected so as to identify the biochemical composition of the aquatic ecosystem (constituents), including those that characterize the natural driving forces and the anthropogenic impact (pollutants) representing the modifying forces; (d) a number of investigations has to be carried out before making the selection among a large number of variables (e.g. water quality criteria, pollution inventories and impacts, water use, etc.); (e) economics of monitoring play a significant role in selection of variables to be sampled. Practically, there are no standard methods that may be used in either the selection of variables or the assessment of an already selected list of variables monitored. To this end, the current paper proposes an approach that may facilitate the selection or assessment procedure. The study presents the above