Capillary cut design for soil-groundwater salinity control

Soil-groundwater salinity issues have assumed a worldwide dimension. It is believed that when groundwater level is less than 2 m there is the possibility of salinity transfer between the soil and groundwater due to factors such as capillary forces. One-dimensional column tests were conducted in the laboratory to find a suitable capillary cut design. The capillary cut material comprised a 20 cm thick 2–4.7 mm and a combination of 2–4.7 mm and 9.5–19 mm gravel material. In all, four different designs were tested by compacting Oji sand in the various columns. Groundwater level of 0.75 m from the top was maintained while salt solution of 10% concentration was allowed to flow under capillary forces through the columns. The water content in the columns were monitored using frequency domain reflectrometry-vector analyzer (FDR-V) after which soil samples from 10 m interval in each column was taken for electrical conductivity measurements. The results showed that 5 cm thick, 2–4.7 mm gravel sandwiching coarser material (e.g. 5 cm thick 9.5–19 mm or 10 cm thick 9.5–19 mm gravel material) proved to be very useful design to cut capillarity.