Hvorslev Method for Water Table Location

In this article we discussed the method used for the measurements of the groundwater level in silty soils.

IS 6935-1973 is used for the measurements of the ground water in borehole in case of silty soils.

Ground water affects foundation design and construction.

GWT depends on seasoned conditions and hence GWT have to be adjusted with climatological and hydrological data of the local, in order to locate the highest and lowest levels during the life of the project.

The method of determining GWL in a borehole varies with the permeability of the soil.

The bearing capacity of the soil besides other factors depends up on the level of the water table  so , the  level of the W.T must be determined with reasonable accuracy.

The method of determining the ground water level in a boring depends up on the permeability of the soil.

In previous  materials like sands and gravels, the water level in the bore hole reaches a final level quickly, after the level is stable , a measuring tape can be lowered in to the borebole for measurement.

In silty soils, the water level in the borehole may not reach a stable position for many days.

Impermeable sand (or) gravel : WL in borehole will reach a final level in a matter of minutes. 

The holes should be cleaned and with a lead weight at bottom can be lowered in to the hole for measuring GWL.

In silts and silty sand : Stabilization of GWT takes few days in such case following methods are used.

a.  Hvorslev(1949) : 

Bailout the water to the estimated WL and measure the levels two or more equal consecutive time intervals. 

The final WL may be estimated as shown below.