TAXA DE INFILTRAÇÃO ESTÁVEL DA ÁGUA AO LONGO DE TRANSEÇÕES EM SOLOS CONSTRUÍDOS NA ÁREA DE MINERAÇÃO DE CARVÃO DE CANDIOTA - RS STABLE WATER INFILTRATIONS ACROSS MINESOILS RECONSTRUCTED AROUND THE CANDIOTA-RS COAL MINING

In order to evaluate the variation of the water infiltration rate at steady-state, two different types of minesoils (SC1, with thin topsoil cover and 2 years of construction, and SC2, with thick topsoil cover and 6 years of construction) were selected and compared to a natural soil (SN) located nearby, classified as an Alfisol. The water infiltration rate was evaluated along a 117m transect at 3.0m intervals, during an average 7,5h period, until constant measurement, using PVC cylinders with 0.1425m internal diameter and 0.25m height, inserted 0.10m into the soil. The measurements were done using a graduated ruler fixed in the internal cylinder after the establishment of a hydraulic head of 0.09m, maintained constant along the time. After the results analysis it was concluded that: (a) the minesoil water infiltration rate at steady- state was low to medium and higher than the reference natural soil, which was very low; (b) the variation of the water infiltration rate along the transect in the minesoil is very high, with extreme values ranging from very low to high, while the variation in the natural soil was lower and more homogeneous; (c) the soils low macroporosity did not allow to establish a significant relationship between this variable and the water infiltration rate.