Overview
ISO/TR 21414:2016 - Hydrometry: Groundwater - Surface geophysical surveys for hydrogeological purposes provides practical guidance for applying surface geophysical methods in groundwater investigations. It recognizes that geophysical applications vary with technology, logistics and investigator expertise and therefore does not prescribe a single field procedure. Instead, it outlines useful guidelines for planning, data collection, processing and interpretation within the limits of modern instrumentation and techniques. The report emphasizes electrical resistivity, electromagnetic (EM) and seismic refraction methods while also covering self‑potential, VLF, seismic reflection and magnetic surveys.
Key Topics and Requirements
- Scope and terminology: Units, definitions and the purpose of geophysical surveys for hydrogeological objectives.
- Planning and logistics: Access, site/area details, equipment selection, safety and field precautions.
- Quality control: Field QC procedures to ensure reliable data acquisition.
- Technique-specific guidance: For each method the TR summarizes:
- Purpose and measurement principles
- Typical instruments and configurations
- Field procedures for acquisition
- Data processing and interpretation considerations
- Advantages, disadvantages and limitations
- Focus areas: Detailed practical coverage of electrical resistivity, frequency-domain and time-domain EM, seismic refraction/reflection, self‑potential, VLF and magnetic surveys.
- Interpretation guidance: General interpretive approaches are discussed; the TR refers readers to specialized texts (listed in its bibliography) for in‑depth theoretical and inversion methodologies.
Applications
ISO/TR 21414:2016 is intended for surface geophysical surveys used in:
- Groundwater exploration and aquifer characterization (depth to water table, lithological boundaries, fracture zones)
- Environmental site assessments (contaminant plume mapping, subsurface heterogeneity)
- Hydrogeological mapping and resource evaluation
- Pre‑drilling reconnaissance and well siting
Practical benefits include improved target definition, reduced drilling risk and cost savings by informing borehole placement and aquifer testing.
Who Should Use This Standard
- Hydrogeologists and geophysicists performing groundwater surveys
- Environmental and engineering consultants conducting site investigations
- Water resource managers and planners evaluating subsurface resources
- Field teams and project managers seeking standardised guidance for survey planning, QC and method selection
Related Standards
ISO/TR 21414 complements other hydrometry and groundwater guidance documents and national survey guidelines. For detailed theory, inversion algorithms and advanced interpretation, consult the specialized texts and references listed in the TR’s bibliography and the ISO catalogue for related hydrometry standards.
Keywords: ISO/TR 21414:2016, hydrometry, groundwater, surface geophysical surveys, electrical resistivity, electromagnetic survey, seismic refraction, hydrogeological investigation.