Modeling of soil moisture movement and wetting behavior under point-source trickle irrigation

Area of Science:

• Agricultural Engineering
• Soil Science
• Hydrology

Background:

• Surface drip irrigation is vital for water conservation in agriculture.
• Understanding soil moisture distribution is key to optimizing irrigation efficiency.
• Emitter discharge rates significantly influence wetting patterns.

Purpose of the Study:

• To investigate soil moisture movement and wetting patterns under varying point source drip irrigation discharge rates.
• To assess the horizontal and vertical extent of soil wetting over time.
• To validate the Drip-Irriwater model's accuracy in predicting soil moisture dynamics.

Main Methods:

• Field experiments were conducted in an apple orchard using discharge rates of 2, 4, and 8 L h⁻¹.
• Soil pits were dug to measure wetted soil width and depth at different irrigation times (30, 60, 120 min).
• The Drip-Irriwater model was used to simulate and validate wetting front predictions against field data.

Main Results:

• Modeled soil moisture dynamics closely matched field observations, with high correlation coefficients (Pearson's r=0.951, correlation=0.918) and a Nash-Sutcliffe efficiency of 0.887.
• Increased emitter discharge rates led to wider and deeper soil wetting patterns.
• Soil moisture content increased with higher flow rates and application times, particularly in the upper soil layers.

Conclusions:

• The Drip-Irriwater model is a practical and accurate tool for predicting soil wetting patterns and moisture distribution under drip irrigation.
• The study provides valuable data for optimizing emitter discharge rates and designing efficient drip irrigation systems.
• Understanding soil moisture dynamics is essential for effective water resource management in agricultural settings.