A geo-electrical instrument for automation of soil moisture monitoring

摘要

Development of operational models for irrigation scheduling, groundwater recharge, etc. has been limited because of extensive data collection requirements in the field. Numerous sensors need to be monitored on a periodic basis appropriate to the scale associated with water movement in the field. For such applications, rapidly responsive sensor networks would replace labour intensive hand measurements, which are often unreliable, in the field. The paper presents development of an instrument (ASRI) capable of automated measurement of soil moisture variation, using the four- electrode resistivity method. In this method, by changing the separation between two electrodes (metallic rods) placed at the ground surface (without digging any holes), the variation in moisture content in the subsurface soil profile can be monitored. The analysis of the apparent resistivity variations at different electrode spacing makes it possible to draw conclusions about the sub surface conditions (e.g. variations in the amount of moisture content in formation).