Geophysical Mapping: Problem Details Problem Name: Temporal variations Problem Type: Groundwater Assigned Methods: + Fluid logging, Flow meter Borehole Methods + Geoelectrics - Tomography (surface based) Electrical Methods + Ground penetrating radar (surface-based) Electromagnetic Methods + Ground penetrating radar - Borehole tomography Electromagnetic Methods 0 DC geoelectrics - Sounding Electrical Methods 0 Electrical and induction logging Borehole Methods 0 Geoelectrics - Crosshole tomography Electrical Methods 0 Refraction seismic tomography (surface-based) Seismic Techniques 0 VLF / VLF-R, Radiomagnetotellurics Electromagnetic Methods    '+' = Technique applicable; '0' = Application possible/limited use