Mapping of Agricultural Subsurface Drainage Systems Using a Frequency-Domain Ground Penetrating Radar and Evaluating...

Area of Science:

• Agricultural Engineering
• Geophysics
• Soil Science

Background:

• Subsurface drainage systems are vital for managing excess soil water in poorly drained agricultural lands.
• Traditional drain mapping methods are invasive, time-consuming, and risk damaging existing infrastructure.
• Non-invasive geophysical sensors offer a promising alternative for efficient and accurate subsurface drainage mapping.

Purpose of the Study:

• To evaluate the effectiveness of a stepped-frequency continuous wave three-dimensional ground penetrating radar (3D-GPR) for subsurface drainage mapping.
• To assess the performance of a 3D-GPR in combination with a single-frequency multi-receiver electromagnetic induction (EMI) sensor.
• To correlate sensor performance with various soil types, ranging from sand to clay till.

Main Methods:

• Deployment of a 3D-GPR with a wide antenna array for subsurface drainage detection.
• Integration and evaluation of a multi-receiver EMI sensor alongside the 3D-GPR.
• Testing the combined sensor system across twelve diverse agricultural study sites.

Main Results:

• The 3D-GPR successfully mapped drainpipes at five sites with sandy, sandy loam, loamy sand, and organic topsoils.
• Drainage mapping success was limited at seven sites due to the 3D-GPR's restricted signal penetration depth in certain soil conditions.
• Electrical conductivity estimates from EMI data correlated with 3D-GPR success, suggesting its utility in explaining performance variations.

Conclusions:

• The 3D-GPR and EMI sensor combination shows potential for non-invasive subsurface drainage mapping, particularly in less conductive soils.
• Soil electrical conductivity is a key factor influencing the penetration depth and effectiveness of GPR for drain detection.
• Further research is needed to optimize sensor performance across a wider range of soil types and hydrological conditions.