Localized RBF meshless methods for modeling unsaturated flow in soils with plant root water uptake
E007 - Data Lab
Abstract
Understanding the dynamics of water flows in unsaturated soils and their interactions with plant root systems are critical for agricultural efficiency, environmental sustainability, and climate predictions. These interactions play a crucial role in the hydrological cycle, particularly within the vadose zone. This zone has a significant impact on subsurface water resources and acts as a reservoir for soil moisture, which offers essential water for plant growth. Our aim is to develop efficient numerical methods for modeling unsaturated flow through unsaturated zone (UZ) with plant root water uptake. The Richards equation and different models for capillary pressure and relative permeability and sink terms due to water uptake by plant roots are used.
The proposed numerical methodologies are based on the localized radial basis function (RBF) meshless methods. These techniques avoid mesh generation and ill-conditioning problems where a sparse matrix is obtained for each global system, which has the advantage of using reduced memory and computational time. The numerical simulations demonstrate the accuracy and computational efficiency of the proposed techniques. The predictions are in good agreement with experimental observations which confirms the reliability of the developed numerical models in predicting unsaturated flow in soils with plant root water uptake.
In the framework of the Observatory of Transfers in the Vadose Zone (O-ZNS) project, these results will be further extended to develop a comprehensive model for multiphase reactive transport of mass and heat transfers through the UZ. This model is expected to play a crucial role in addressing key challenges such as ecological transition, groundwater protection, and sustainable water resource management. The study will be applied on a representative scale of the Beauce aquifer, leveraging extensive and high-resolution data from the O-ZNS in Villamblain, France. The observatory’s unique setup, which includes a 20-meter deep well with a diameter of 4 meters, multiple boreholes, and innovative environmental sensors, provides high-resolution 3D measurements of fluid flow and heat/mass transfer processes. These measurements are crucial for the construction of a detailed hydrogeological model and to gain an in-depth understanding of the system’s dynamics.