Automation of the measurement of time record in determining the hydraulic conductivity of saturated soil

Camila P Cagna,Alexandre R C Silva,Osvaldo Guedes Filho,Cássio A Tormena

doi:10.1590/1807-1929/agriambi.v26n2p149-155

Abstract

ABSTRACT The objective of this study was to automate the acquisition of water travel time, as well as the computation of hydraulic conductivity of saturated soil by the falling head method, using water sensors and the Arduino platform. To automate the measurement of travel time, the Arduino Uno board was used, and two water sensors were installed at the initial (h0) and final (h1) heights of the water inside the core. When the water flows across the soil and the water level passes the bottom part of the initial sensor (h0), the time recording starts; it ends when the water is absent from the final height of the second sensor (h1). The equation for calculating the hydraulic conductivity was inserted into the algorithm so the calculation was automatic. Undisturbed soil samples were taken in a long-term no-tillage area. There were no significant differences for the time and hydraulic conductivity means between the permeameters. The coefficient of the residual mass index showed an overestimation of the time variable; thus, the automated permeameter improves the precision of time recording and saturated hydraulic conductivity estimated by the falling head method.

Highlights

Soil hydraulic conductivity represents the ease with which water moves into the porous soil system and is an important variable in studies on soil management, crop production, and the transport of chemical elements (Oliveira et al, 2003; Mesquita & Moraes, 2004; Gonçalves & Libardi, 2013).There are several methods to determine hydraulic conductivity both in the field and in the laboratory
The objective of this study was to automate the acquisition of water travel time, as well as the computation of hydraulic conductivity of saturated soil by the falling head method, using water sensors and the Arduino platform
When the water flows across the soil and the water level passes the bottom part of the initial sensor (h0), the time recording starts; it ends when the water is absent from the final height of the second sensor (h1)

Summary

Introduction

There are several methods to determine hydraulic conductivity both in the field and in the laboratory. Tests under laboratory conditions have some advantages, such as the control of boundary conditions (saturation, hydraulic load, and flux direction), time efficiency, and low costs (Marques et al, 2008). The falling head method uses undisturbed soil samples previously saturated and submitted to variable hydraulic loads (Reynolds & Elrick, 2002). Using this approach, the time spent by the water to pass from the initial to the final height is determined via a chronometer. The automation of the measurement of time through the water sensors and algorithms represents an improvement in obtaining the hydraulic conductivity of saturated soils

Objectives

Methods

Results

Conclusion