Marcos Cleve Alves da Silva
◽
Marcelo Dos Santos Targa
◽
Vicente Rodolfo Santos Cezar
The velocity of water infiltration in soil is important for the design of irrigation systems, drainage, septic tanks, sanitary landfills, dams, channels for water distribution, soil and water management to control erosion and estimate surface runoff. Infiltration tests are generally done with rulers and visual reading, which can lead to errors. The present study therefore aimed to determine the Infiltration Velocity (IV) curves of water in the soil by the concentric ring infiltrometer method, using an Arduino microcontroller and an ultrasonic sensor to measure the lowering of the water depth. For that, in the same infiltration test, four readings in Automatic mode (AT) and four readings in Manual mode (MN) were performed simultaneously, in a red-yellow Argisol type soil, in the Areal Basin, located in the southeastern region of Brazil. municipality of Taubaté, Vale do Paraíba, in the state of São Paulo. Adjustments of kostiakov curves and their equations were made from the data obtained in the field, and the values of R² were determined, as well as the values of Basic Infiltration Velocities (BIV), Accumulated Infiltration (AI) and the Average Percentage Error (APE) of the calculated IS values and those estimated by the equations. The results show that the number of readings in the same test time in Automatic mode (AT) was 2.3 times higher than in the manual (MN). All tests showed that the Red-Yellow Argisol showed a high infiltration speed, and in the pasture area the BIV values were 1.9 times higher than those obtained in the forest area. The R² determination coefficients for all curves are 0.99 in all tests and demonstrate the strong correlation between the data. The APE of the calculated and estimated IS values were low, and the biggest discrepancies that occurred were (APE = 0.30%) in the MN - 4 test and (APE = -0.01%) in the AT - 4. APE of MN mode BIVs for AT was 2.7%. These differences in IS values are reflected in the accumulated infiltration (AI) in the soil over time, and in this study the AI of the ATs tests was on average 4.1mm higher than in the MN tests, which corresponds to a difference of 41m³ ha-1. It was concluded that the use of the Arduino microcontroller with the ultrasonic sensor installed in the ring infiltrometer proved to be efficient in the field measurements and made the determination of the accumulated infiltration and the infiltration speed practical, proving to be an economical and technically viable alternative mainly due to the quantity of possible points to collect for each test and the greater reliability added to the low error values when compared to the manual.
On the Origin of Deep Soil Water Infiltration in the Arid Sandy Region of China
