Determination of Sorptivity, Infiltration Rate and Hydraulic Conductivity of Loamy Sand using Tension Infiltrometer and Double-Ring Infiltrometer

Abstract

This study was conducted to assess the effectiveness and accuracy of tension infiltrometer (TI) over double ring infiltrometer (DI) for determining infiltration rate (I) of loamy sand. Sorptivity (S), infiltration rate and hydraulic conductivity (K) are soil properties that govern the rate of entry of water into the soil and its movement within the soil. The ease and accurate measurement of these properties depend on the instruments used. DI operates by ponding water and could be affected by preferential water flow during infiltration test which could not be avoided especially on a fertile soil. DI and TI at water potentials of -0.02, -0.04, -0.05 and -0.06 m were used to determine infiltration rate of the soil. The mean values of sorptivity for DI and TI at water potentials of -0.02, -0.04, -0.05 and -0.06 m were 847.02, 63.50, 33.15, 29.90 and 19.46 mm/h1/2, respectively. Mean values of infiltration rates for DI and TI at -0.02, -0.04, -0.05 and -0.06 m water potentials were 471.26, 176.84, 73.73, 71.32 and 37.73 mm/h, respectively. Mean values of hydraulic conductivity for DI and TI at -0.02, -0.04, -0.05 and -0.06 m were 344.45, 22.42, 18.61and 16.83 mm/h, respectively. DI required 100-150 litres for the infiltration test, difficult where water is very scarce and gave higher values of infiltration rate. TI saved water (2-3 litres), controlled preferential water flow and values of S, I and K were within the range obtained by other researchers. TI is more effective for measuring hydraulic properties soil than DI.Keywords:Double ring infiltrometer, tension infiltrometer, sorptivity, infiltration rate, hydraulic conductivity