مدل دو بعدي حركت آب در خاك همراه با جذب آب توسط ريشه بر اساس حل معادلات حاكم و مطالعات ميداني

Investigation of 2D Water Flow in Soil with Root Water Uptake Based on Solution of Governing Equation and Field Studies

Soil water movement with root water uptake is a key process transport of water and chemicals in the soil- plant system. In this study, two-dimensional root water uptake model was developed, which can be incorporated into numerical flow models. Root water uptake model includes root density distribution function, potential transpiration and soil water stress-modified factor. Root water uptake parameters were optimized, minimizing the residuals between simulated and measured water content data. Tube-time domain reflectometry (TDR) was used to measure soil volumetric water content around a surface-irrigated apple tree at 12 locations. The measured data are compared against the outputs from the numerical simulation of the soil water dynamics that uses Richardsʹ equation. It shows that 30% of water was drawn from the radial distance of 30-60 cm and average water uptake from the soil layer of 20-40 cm accounts for 60% of the total water uptake. Simulated and measured water contents were in excellent agreement (R2=0.97). Potentially the numerical model is a useful tool to various problems related to flow transport with plant water uptake in variably saturated soils. Keywords: Numerical model, Richardsʹ equation, Root water uptake, Unsaturated, Water flow Journal of Water and Soil Jfca*