PD ISO TR 21414:2016 pdf free

PD ISO TR 21414:2016 pdf free.Hydrometry一Groundwater一Surface geophysical surveys for hydrogeological purposes
The application of geophysical methods is an evolving science that can address a variety of objectives in groundwater investigations. However, because the successful application of geophysical methods depends on the available technology, logistics, and expertise of the investigator, there can be no single set of field procedures or approaches prescribed for all cases. This Technical Report provides guidelines that are useful for conducting geophysical surveys for a variety of objectives (including environmental aspects), within the limits of modern-day instrumentation and interpretive techniques,are provided. The more commonly used field techniques and practices are described, with an emphasis on electrical resistivity, electromagnetic, and seismic refraction techniques as these are widely used in groundwater exploration. Theoretical aspects and details of interpretational procedures are referred to only in a general way. For full details, reference is intended to be made to specialized texts listed in the Bibliography.
Geophysical surveys play a vital role in groundwater exploration. Surveys can be used to conduct either shallow subsurface investigation that may be needed for many environmental-related projects or for deeper investigations that may be required to identify productive aquifers. Also, surveys can be used to delineate bedrock topography, estimate the thickness of weathered zones, demarcate fracture geometry, identify the presence of limestone cavities and/or paleo-channels, and to assess quality of groundwater. Furthermore, surveys can be used to assess groundwater contamination and the movement of plumes, define vadose zone characteristics required for waste disposal or artificial recharge projects, demarcate sea water intrusion, differentiate between aquifers and aquitards,monitor the quality and direction of groundwater movement, etc.; geophysical measurements are also used to estimate hydraulic parameters of aquifers.
Geophysical methods can be grouped into two categories: natural field methods and artificial source methods. Commonly used natural field methods include gravity, magnetic, and self-potential methods,which measure variations in the earth’s gravity field, magnetization of rocks and earth’s natural kinetic potential. Microgravity techniques can detect changes in groundwater storage and identify saturated cavernous limestone features. Artificial source methods measure the response of the subsurface to artificially induced energy like seismic and electromagnetic waves and electrical currents. These methods include electrical resistivity, induced polarization, Very Low Frequency (VLF) electromagnetic,controlled-source electromagnetic, seismic refraction and, occasionally, seismic reflection.PD ISO TR 21414 pdf free.