Water diffusion characteristics of vegetation concrete under buried infiltration irrigation

Numerous steep slopes resulting from infrastructure construction drastically affect ecological landscapes. The vegetation concrete (VC) ecological slope protection method efficiently rehabilitates slope ecosystems. Despite advancements in the construction process, the standard irrigation maintenance method for slope vegetation remains unspecified. Three principal factors affecting VC water diffusion from production to application are: site conditions, irrigation design parameters, and substrate preparation standards. This study employed an energy-efficient porous ceramic emitter in buried irrigation equipment to investigate the effect of slope, water head, and bulk density on water diffusion patterns, analyzing both apparent and fine-scale dynamics through laboratory experiments and numerical simulations. The results demonstrated a positive correlation between slope and water head with the distance of wetted front. However, bulk density showed a negative correlation. The power function exhibited optimal fitting for wetted front advancement over time, with the 'power0-type' function most precisely representing the VC wetted front movement (R²> 0.99). The water content, utilized to assess the precision of the HYDRUS simulation grounded in the van Genuchten model and the centrifuge method (p<0.05), exhibited discrepancies with the wetted front while revealing a robust logistic correlation with irrigation duration. The root-mean-square error, mean absolute error, and percent bias between the observed and simulated water contents were 0.85%, 0.74%, and -3.50%, respectively. The VC soil hydrodynamic parameters, specifically the inverse of the intake suction, the pore-size distribution exponent, and the shape factor, were quantified as 0.019, 1.329, and 0.248, respectively. Water head significantly influenced water transport more than slope; yet, irrespective of their combination, extended irrigation generally intensified the 'instability' of water diffusion. To regulate slope substrate moisture through water diffusion in practical conditions, it is advisable to prioritize the modification of VC preparations, followed by the design of an appropriate irrigation pressure, and finally the selection of an optimal location for the irrigator's deployment. The findings of water diffusion through a semi-rigid composite substrate broaden the applicability of soil hydrodynamics theory to composite soils and enhance its implications through conceptual and practical advice.