Sampling frequency for monitoring the actual state of groundwater systems

Sampling frequency is a very important variable in the design of a groundwater monitoring network. Given the objective of sampling as monitoring the actual state of groundwater systems, criteria for the determination of sampling frequency can be based on the trend detectability, the accuracy of estimation of periodic fluctuations and the accuracy of estimation of the mean values of the stationary component of the state variables (such as groundwater heads, temperature, and concentration of hydrochemical constituents). The' criteria are applied to the determination of sampling frequency for monitoring groundwater levels around the Spannenburg pumping station. The analysis and verification of the sampling frequency indicate that the most appropriate sampling frequency is once a month.