Comparison of soil use in the infiltration of rainwater: Pasture and forest

Abstract

The lowlands of the forests of Itajaí/SC, Brazil were extensively and predominantly fragmented into urban settlements, port facilities, and rice plantations. In addition to climate change events and existing environmental conditions, the region is susceptible to flooding. Consequently, this study aims to analyse the hydrologic functioning of the lowland forests in the infiltration of rainwater in Itajaí. A map of land use and occupation was created using the Geographic Information System – GIS, and crossed with the soil maps of the city. Two areas with the same soil classifications were selected; a pasture area and a forest area. In August and October, these areas were sampled and classified according to the following criteria: grain size, moisture, permeability, and organic matter content of the soils. The infiltration rate of the soils in the sample units was tested using the double ring infiltrometer. Analysis of variance (ANOVA) was used to verify the correlation between the obtained values. The average values for the samples obtained in areas without vegetation were 3.45 cm h-1and 3.60 cm h-1 in August and October, respectively. In the area with forest vegetation, the average values were 19.05 cm h-1and 8.70 cm h-1for the samples obtained in August and October, respectively. Although the soil conditions were the same, this study found significant differences in the water infiltration rates in the soil surface between the forest areas and the areas without vegetation. The forest vegetation denotes its potential role in the infiltration of rainwater in the floodplain of area.