Subsurface Sensing, Subsurface Aquametry

An attempt is started to define the terms of aquametry and its adjective subsurface. Subsurface Sensing represents a field of scientific research and development character, which is much wider than that of the classical non-destructive material testing in industrial production. It covers the 2 or 3D mapping of distributed parameters, broad application fields, the interactions of waves and beams with matter, signal propagation in media, almost all sensing techniques like radar, optical, acoustic and nuclear sensors as well as the measurements of material properties. Dielectric sensing dominates in the water content determination, i.e. in aquametry. The problems of aquametry are critically commented: Proposals of free and bound water definitions are made. The volume-related water content determination is preferred. The reference method, i.e. oven drying, impedes the development. The calibration or relation to the water content in indirect measurements is discussed. Optimum measuring frequency is treatedas well. Subsurface Aquametry is introduced as a development of Microwave Aquametry and Dielectric Aquametry. Also, dielectric water research is involved. By providing included and excluded examples and accepting the basic features of common Aquametry, the subject is defined with a call for contributions.