Hydraulic characterization from porous aquifers of the Brazilian Federal District

Abstract

Hydraulic conductivity (K) in unsaturated soil is a key input parameter for modeling subsurface water and solute movements. K-values are also important to better define the potential of aquifers and to optimize water resources management activities. Since K-values are usually not readily available, different techniques are applied to estimate them. This study aimed to estimate unsaturated K-values from porous aquifers found in the Federal District of Brazil. Infiltration tests were conducted in different soil types using the open-end-hole approach and the permeability test using shallow boreholes with specific depths, as reported by Heitfeld in 1979. Soil structure was taken into consideration in such estimations. In order to consider important soil properties such as soil texture and bulk density, K-values were also estimated by means of pedotransfer functions (PTFs). Soil texture was determined in the laboratory and used as input parameter for PTFs. Results from open-end-hole method and permeability test compared to those obtained from pedotransfer functions. K-values from four different shallow porous aquifers systems encountered in the Federal District varied from 10 -8 ms -1 to 10 -6 ms -1 . Highest K-values were found in Oxisols while the lowest rates were found in Inceptisols. Decreasing conductivity trend was found with increasing depth due to the increase of loamy soils. Variations in the rate of hydraulic conductivity indicated heterogeneity of porous aquifers due to differences in textural and structural characteristics of the soils.KEYWORDS: unsaturated hydraulic conductivity; open-end-hole; pedotransfer functions. RESUMO: A condutividade hidráulica (K) em meios não saturados é um parâmetro essencial para modelar fluxos de água e solutos no subsolo. Os valores de K são também importantes para estimar o potencial dos aquíferos e otimizar a gestão de recursos hídricos. Tais valores geralmente não estão disponíveis e diferentes técnicas são aplicadas para obtê-los. O objetivo deste estudo foi estimar valores de K em meios porosos não saturados na região do Distrito Federal (DF). Foram realizados testes de infiltração em diferentes tipos de solo, utilizando o método open-end-hole, e ensaios de permeabilidade, em poços rasos com profundidades específicas, como descritos por Heitfeld (1979). Em tais estimativas a estrutura dos solos foi considerada. Valores de K também foram estimados por meio de funções de pedotransferência (PTFs

Evolution of Land Use in Two Drainage Basins in an Urban Area of Brasília-DF/Brazil

“…The predominant reliefs of the drainage basins were classified as Superior Planing, with less than 3% of the declivity. The original soils are already highly altered due to the anthropic activities triggered by the urbanization process and mechanized agriculture (Campos, 2004;Gonçalves et al, 2015;Salles et al, 2008;Steinke & Sano, 2011).…”