Numerical Investigation into the effects of rainfall and long stem plants spacing on Root Water Uptake (RWU)

¹ DICAM Department, Alma Mater Studiorum, Università di Bologna, viale del Risorgimento 2, Bologna, 40136, Italy.
² Priority Research Centre for Geotechnical Science and Engineering, The University of Newcastle, Callaghan, NSW, Australia.

^* Corresponding author: andrew.vidler@uon.edu.au

Abstract

Woody plants on earthen slopes are a bioengineering solution for the prevention of shallow landslides that occur mostly during a wet season. From a soil-hydrological point of view, slope stability is influenced by plant roots reducing soil water content through transpiration. Despite this, conventional engineering practice tends to ignore the effects of Root Water Uptake (RWU), in part due to the complexity of soil-vegetation-atmosphere interactions. This paper investigates the hydrological effects of plants, which involved seepage simulations performed on two different soil types. Each soil was exposed to different rainfall intensities, and the influence of plants over time was seen from the RWU over time for different configurations of plant spacing and canopy densities. This information with in-situ rainfall data, is useful to assess the effectiveness of plants for slope stability. Further, the relative importance of different mechanisms acting in soil-plant-atmosphere interactions was seen in the RWU data. Although the conducted simulations refer to a horizontal soil profile, the results are useful in more complex geometries such as earthen slopes and may help the design of bioengineering solutions (woody plants) and slope stability assessment. Future research is aimed to investigate additional soil-vegetation-atmosphere mechanisms and additional model geometries and plant species.