law NWIC WIMS data NHNS pipes India DWLRs August device voltage January Faraday November flow rate CGWB EMFM principle something piezometers flow velocity magnetic field regional scale open dug wells March/April/May conductive fluid telemetry systems different context Management System Water Information groundwater levels additional details monitoring network conductive liquids groundwater monitoring More Details Contac Us water level measurements electromagnetic induction 25,000 monitoring stations Electromagnetic Flow Meter Hydrograph Network Stations Allegiance Water Management Ground Water Level Monitoring Digital Water Level Recorders purpose-built bore/tube wells The Central Ground Water Board National Water Informatics Centre automatic high-frequency monitoring