Optimization of sampling frequency for routine river water quality monitoring

Sampling frequency is an important factor to be considered during the design of a water monitoring network, and the cost-effective selection of possible ways and means for the optimization of sampling frequency is still needed. This paper introduces water pollution index deviation ratio comparison (WPI DRC), a procedure for the optimization of sampling frequency for a routine river water quality monitoring system. Sampling frequency optimized using WPI DRC at monitoring station X5 in the mainstream of Xiangjiang River is compared with that established using the traditional Statistical Algorithm method. The result of comparison indicates that WPI DRC is more feasible than the traditional one. And then, the sampling frequencies for other 16 monitoring stations also have been optimized, and the results show the sampling frequencies of all the stations except that X4 are reduced, and there is no unacceptable difference between water quality evaluation results at 17 stations before and after the optimization. Therefore, it is concluded that WPI DRC is an effective optimization process with operable results, which can be used to fulfill the requirement of practical monitoring work.