Abstract:
This study investigates the potential use of geosynthetic materials as capillary
barriers to enhance water retention in landscaping soils. Soil was first classified
using Unified Soil Classification System (USCS), then Van Genuchten model was
used to model and compare unsaturated hydraulic characteristics of the soil and
geosynthetic materials. Five different materials; gravel, sand, Needle Punched 50
(NP 50) geotextile, Thermally Bonded (TB) 9 and (TB) 21 geotextiles were used
together with silty clay to create capillary barriers in five different 500mm deep
soil columns to determine how each of the materials influences the amount of
water stored. Water infiltration was allowed into each of the columns
constructed as capacitive moisture sensors tracked change in moisture content in
the soil. The air entry pressure and residual matric suction for the materials was
determined from Water Retention Curves (WRCs) and compared to water
content retained in each column. This study concluded that properly designed
capillary barrier can be used to increase water retention in landscape soils. It was
also demonstrated that geosynthetic materials with the higher residual matric
suction (NP 50 and sand) stored more water compared to the ones with the
least (TB 21 and TB 9).