Optimization of Water Quality Monitoring Networks

Abstract

At the moment the water quality monitoring network in the main surface waters in The Netherlands includes almost 400 sampling locations with a sampling interval of 1 to 4 weeks. The number of water quality variables analysed varies per location from 15 up to 100. Recent developments, such as limiting financial and laboratory capacities and changing objectives of the routine water quality investigations, necessitate an optimization of this monitoring network. Being an essential element in the optimization procedure, a relationship has to be found between the cost of obtaining information from the network and the effectiveness of the information, the latter being strongly dependent on the objective(s) of the network. In this paper a general optimization approach is presented. Also a method is proposed, worked out and applied, that relates the effectiveness of the information to the sampling frequency of the water quality monitoring network. This method can be used for the optimization of the sampling frequency for the main objectives of the routine water quality research i.e. the detection of trends in water quality constituents.