DEFINITION OF GROUNDWATER LEVEL

Mapping the surface of full water saturation by GPR


The surface of the total water saturation in the soil is a strong reflective boundary for high-frequency electromagnetic waves, so it is usually clearly displayed in GPR sections.
Depending on the type and operating frequency of the receiving antennas in sandy soils it is possible to trace the position of the groundwater level in the depth range of 1-15 m.
The section also shows the areas of increased saturation in the lenticular and bedded lithological heterogeneities with higher porosity.

Assessment of water saturation of soil foundations of the piers

Suffosion processes in the soil foundations of port berths and quays, which occur under the influence of fluctuations in water level and the impact of the screws mooring ships, represent a real danger of failures and destruction of hard surfaces and subsequent costly repairs.
On the GPR sections areas of increased water saturation in sandy soils are shown, the boundary between bulk soils of different composition, possible voids under the hard floors in areas of subsidence due to soil suffusion and removal of small sand fractions through the wall of the pier.
The surface of full water saturation is often the last reflecting geological boundary on the GPR section.

Determination of groundwater level by seismic methods

The seismic method of the refracted waves in many cases allows to establish position of level of ground waters in homogeneous arrays of sandy-clay soils, such, for example, as moraine loams of high power. The GPR method in such soils containing a large percentage of clay material is ineffective.
A sharp increase in the velocity of longitudinal wave propagation at the boundary of full water saturation forms a strong refractive boundary, well traced in the velocity sections. Seismic boundaries associated with the water saturation surface have a clear correlation with the static penetration test data (CPT) – frontal resistance to cone, lateral friction and pore pressure.