Infiltração e redistribuição da água em solos irrigados por gotejamento: caracterização do avanço da frente de molhamento

Abstract

Water efficiency makes dripping the most expansive irrigation system in modern world agriculture. One of the observable characteristics in drip irrigated soil is the wetness front. The use of mathematical models to estimate the dimensions of this front is important for the design of drip systems, using the saturated hydraulic conductivity (KS) of the soil as a parameter of adjustment and calibration. The Beerkan semiphysical method determines the hydrodynamic properties of the soil, among them, KS. Thus, this work aimed to investigate the relationship between the advance of the soil wetness front in a drip irrigation system and with a semi-physical method. The experiment was carried out at UFRPE/UAST, irrigating two soils (FAr and FAAr), through three driping irrigation systems, with three different flow rates (2.8, 4.4 and 8.3 L h-1) for ten intervals of time (5, 10, 15, 20, 30, 40, 50, 70, 90, 110 min.). The measured dimensions were diameter (d) and depth (p), given in centimeters (cm). Soils FAr and FAAr obtained similar values for the observed dimensions (d and p). The best time irrigation responses for the Soil FAr were found for the 8.3 L h-1 flow for 30 min of irrigation for (d), and 8.3 L h-1 for 50 min for (p). In the FAAR soil, the best responses were flow 8.3 L h-1 for 50 min and flow 8.3 L h-1 for 70 min for (d) and (p), respectively. It was possible to estimate the geometrical dimensions of the wetness front, diameter and depth from the Ks obtained from the Beerkan methodology. The estimated dimensions from Ks obtained a positive correlation with the observed dimensions, with R2 > 0.90 for all correlations. The adjusted equations can be used to estimate the area and volume of wet soils for all flows at any time interval.