Infiltration of rain water in semi-arid areas under three land surface treatments

Abstract

The effect of soil surface conditions on the infiltration of the rainfall water (and subsequent soil moisture profile evolution) was investigated. Three different soil surface conditions were considered. In the first case the surface soil layer was rototilled (RT) and kept free of natural vegetation. In the second the soil surface layer was undisturbed and kept free of vegetation (NT). In the third the soil surface layer was undisturbed and natural vegetation was allowed to grow (NV). The experimental work took place in the semi-arid region of Attica (Greece).From the soil moisture profile development, gains and losses of water and moisture differences were recorded. It was found that, during the rainy period more water was infiltrated and stored in the RT in comparison with untilled bare soils and NV plots. Between RT and NT bare soils there is a positive difference about 10% of precipitated water which has been stored in the RT profile. The effect of rototillage is more pronounced during the early stages of the rainy period as it results in more water stored in the profile. However, after the period of rains water losses, were higher for the NV and RT plots in comparison with the NT plots which may be attributed to higher evaporation losses.It was found that tillage reduces bulk density which results in changes in the moisture retention curves accompanied by reduction of the hydraulic conductivity at saturation Ks. Moisture retention curve changes were more pronounced at relatively low pressure head values (H) with an increase of moisture content (θ) at saturation in the tilled plots. It was further found that the hydraulic conductivity function K(θ), in the tilled plot, as this is estimated through the employment of the conceptual model of Mualem–van Genuchten, retains higher values at relatively low to moderate water contents and lower values at relatively high water contents in comparison with the untilled plots.