Design of a pipeline sensor-based platform for soil water content monitoring

Abstract

This paper presents a sensor-based platform that travels through an underground pipeline system and monitors the soil water content in real time. It consists of a modified commercial soil water sensor (Diviner 2000), which is placed on two circular articulated wheeled bases, each of them driven by a small wheeled electric motor. An electronic module allows the user to control the platform by sending commands (move one step forward or backwards) from the ground station. Experiments were carried out in laboratory conditions in an artificial tank 10 m long by 0.6 m wide, and with a depth of 0.4 m (total volume 2.4 m3). The PVC pipelines were placed horizontally at depths of 0.1 m and 0.3 m under the soil surface. The sensor-based platform demonstrated very good mobility and produced records of the soil water content in the different horizons. The recorded values were then plotted as volumetric water content (m3 m−3) versus time. The application to a border irrigation case study provided the spatial variability of the water content, so that precise information about the soil environment was gathered. Also, in a drip irrigation case study, the sensor-based platform gave important information about the technical stage of the drip irrigation system. Thus, the measurement of soil water using the proposed method is more effective than measuring the soil water status at a single point and assuming soil homogeneity.