Knowledge about soil moisture dynamics and their relation with rainfall, evapotranspiration, and soil physical properties is fundamental for understanding the hydrological processes in a region. Given the difficulties of measurement and the scarcity of surface soil moisture data in some places such as Northeast Brazil, modelling has become a robust tool to overcome such limitations. This study investigated the dynamics of soil water content in two plots in the Gameleira Experimental River Basin, Northeast Brazil. For this, Time Domain Reflectometry (TDR) probes and Hydrus-1D for modelling one-dimensional flow were used in two stages: with hydraulic parameters estimated with the Beerkan Estimation of Soil Transfer Parameters (BEST) method and optimized by inverse modelling. The results showed that the soil water content in the plots is strongly influenced by rainfall, with the greatest variability in the dry–wet–dry transition periods. The modelling results were considered satisfactory with the data estimated by the BEST method (Root Mean Square Errors, RMSE = 0.023 and 0.022 and coefficients of determination, R2 = 0.72 and 0.81) and after the optimization (RMSE = 0.012 and 0.020 and R2 = 0.83 and 0.72). The performance analysis of the simulations provided strong indications of the efficiency of parameters estimated by BEST to predict the soil moisture variability in the studied river basin without the need for calibration or complex numerical approaches.

Wastewater from textile industries is loaded with synthetic dyes. These effluents are often not adequately treated, affecting the soil and groundwater quality and leading to environmental contamination. The Agreste mesoregion of the state of Pernambuco is home to one of the largest textile centers in Brazil. This work therefore aims to study the behavior of Remazol Black B (RB5) dye in subsurface mediums in this region. The kinetics and isotherm sorption experiments allowed an evaluation of RB5 retention capacity in two layers of alluvial soil of the dry riverbed of the Capibaribe Basin. The maximum sorption rate was 81.81 mg kg-1 and 21.7 mg kg-1 for the loamy sand and sand layers, respectively. The Pseudo-second order kinetic model described more appropriately the sorption kinetics for both soils. The isotherms behavior was nonlinear, and Freundlich model was the most suitable to describe this process for both soils, presenting KF values of 8.6407 L kg-1 for loamy sand and 0.1868 L kg-1 for sand. The isotherm parameters confirm a more significant interaction of RB5 with the loamy sand layer than with the sand layer, indicating lower leaching in the first layer, which is less mobile for RB5 contamination. Furthermore, the different sorption rates for both soils indicate the importance of studying the soil as a heterogeneous profile.

The permeable pavement is a compensatory drainage technique for urban waters that aims to control runoff and to ensure ideal hydrological conditions. This work had as main objectives to evaluate the infiltration capacity of a permeable pavement (PP) at real scale, through analytical and numerical modeling. It relies on water infiltration experiments and related modeling for the hydrodynamic characterization of the coating layer (saturated hydraulic conductivity, Ks , and sorptivity, S). A large panel of analytical and numerical models was considered, and several estimates were obtained. Then, the criteria for the evaluation of the maintenance requirement of the permeable pavements were computed for all the Ks -estimates considering the NCRS standards (assessment of permeability levels). The results indicated nice fits and accurate estimates for both the saturated hydraulic conductivity and the sorptivity. However, the Ks -estimates depended on the considered model and led to contrasting results in terms of classification. For 8 of the 9 models, the value of the Ks -estimate leads to the classification of “Group A” of the NCRS soil classification, meaning a very permeable material. In contrasts, the last method (numerical inverse modeling) classified the permeable pavement as “Group D”, i.e., soils with low permeability. Those results show the importance of the selection of characterization methods regarding the assessment of the hydrological classification of permeable pavements.

The semiarid region of Pernambuco has a large water deficit, leading the population to explore groundwater resources such as alluvial aquifers. The state of Pernambuco also stands out for having the second-largest textile manufacturing center in Brazil. However, the direct discharge of textile effluents from the region's industries has intensified the negative impacts on water conservation and alluvial soils. This work characterized the sorption of Direct Black 22 dye (DB22) in two layers of alluvial soil in the Capibaribe-PE basin. Batch experiments (kinetics and sorption isotherms) allowed the evaluation of the retention potential and mobility of this compound in this environment. Sorption kinetics were verified for stirring times of 0.25; 0.5; 1; 2; 4; 6; 8; 10; 12; 24; 48 and 72 hours and the experimental data was adjusted to the first- and second-order kinetic models. The isotherm occurred with concentrations of 1; 5; 10; 15; 20; 32.5 and 40 mg.L-1 and experimental data was adjusted to the linear, Freundlich and Langmuir models. The sorption kinetics of DB22 was best described by the second-order model, while the Freundlich and Linear models properly fitted sorption isotherms for Layers 1 and 2. The organic matter contents and the cation-exchange capacity of the soil layers influenced the sorption of the dye. The superficial layer privileges dye retention phenomena, while in the subsurface layer dye mobility phenomena prevail.

The semi-arid regions of northeastern Brazil have historically suffered from water shortage. In this context, monitoring and modeling the soil moisture’s dynamics with hydrological models in natural (Caatinga) and degraded (Pasture) regions is of fundamental importance to understand the dynamics of hydrological processes. Therefore, this work aims to evaluate the hydraulic parameters in Caatinga and Pasture areas using the Hydrus-1D inverse method. Thus, five soil hydraulic models present in Hydrus-1D were used, allowing the comparison of the single-porosity model with more complex models, which consider the dual porosity and the hysteresis of the porous medium. The hydraulic models showed better adjustments in the Caatinga area (RMSE = 0.01–0.02, R2 = 0.61–0.97) than in the Pasture area (RMSE = 0.01–0.03, R2 = 0.61–0.90). Regarding the hydraulic parameters, for all models, the Pasture showed smaller saturated hydraulic conductivity and water content values of the mobile region than the Caatinga. This fact demonstrates the negative impact of compaction and change in natural vegetation in the Brazilian semi-arid. The dual-porosity model presented the best fit to the data measured in the Pasture area. However, a single-porosity model could be considered representative of the Caatinga area. The results showed that Caatinga areas contribute to maintaining soil moisture and increasing the water storage in semi-arid regions.