Water temperature effect on hydraulic conductivity and infiltration rate of soils

Abstract

The effects of temperature of applied water on the hydraulic conductivity (HC), infiltration rate and crust formation were studied on two soils from the Transvaal. The HC was studied using soil columns whereas infiltration rate and crust formation were investigated by subjecting the soils to simulated rain of two intensities, 25 mm h⁻¹ and 45 mm h⁻¹. Water temperatures for the HC study were held constant at 8°C, 21 °C and 45°C. The results showed that increasing water temperature caused a significant increase in the HC of the soils studied. This increase was attributed to a decrease in water viscosity. In the case of the infiltration rate and crusting 10°C and 45°C temperature treatments were studied. Neither the rate at which the crust was formed nor its final infiltration rate (FIR) were affected by changes in the temperature, and hence the viscosity of the water. Furthermore, the FIR remained unaffected by the water temperature when the rain intensity was changed. It is suggested that the conditions under which the water is applied to the soil determine the sensitivity of soil permeability to changes in the water temperature. When soil is exposed to water with energy (e.g. rain or overhead irrigation) the change in temperature of the water does not affect the susceptibility of the soil to crust formation and hence its permeability. On the other hand when no energy is involved during water application water temperature has a significant effect on the permeability of the soil.