Case study for determination of a water level monitoring frequency for nationwide groundwater monitoring networks in Korea

The Korean Ministry of Construction and Transportation (MOCT) and the Korean Ministry of Environment (MOE) manage the National Groundwater Monitoring Stations (NGMS) and the Groundwater Quality Monitoring Stations (GQMS) under Article 17 of the Groundwater Act. Under the same legislation, local government will install or designate an additional 10,000 monitoring wells as Subsidiary Groundwater Monitoring Stations (SGMS) by 2011. However, a standard for the installation and management of the SGMSs has not yet been developed. This study focuses on the development of a model for the determination of optimal monitoring frequencies during the manual measurement of the SGMSs. The groundwater level time series for the 81 deep and shallow monitoring wells making up the NGMSs were analyzed using an AR( p) model, and a harmonic series model was then made for the determination of groundwater level sampling frequency in the SGMSs. The result showed that the average sampling frequency necessary for groundwater level monitoring is about once every 8.9 days. Moreover, it indicates that water level sampling needs to be performed more frequently in steeply inclined sites, deep wells, and in monitoring wells belonging to an AR(2) rather than an AR(1) model.